Science 3

SCIENCE III

Module 1 Chemistry and You What this module is about The study of chemistry is interesting for many reasons. It explains events in nature, ittouches nearly every aspect of human life, and it plays a vital role in the daily activities wedo at home or elsewhere. Chemistry has been called the central science because it isessential to the study of other sciences. Like all other sciences, the study of chemistry isfun. This module can help you look at the world in ways you have never imagined. Ittackles the importance of chemistry in our daily lives. It also looks at the desirable qualitiesand attitudes of some Filipino and foreign scientists that lead them to develop newtechnologies. Lastly, it discusses scientific measurements and their applications. This module contains the following lessons:  Lesson 1 – Chemistry: Its Beginning and Importance to Human Life  Lesson 2 – Desirable Qualities and Attitudes of Scientists in the Field of Chemistry  Lesson 3 – Scientific Measurements Read this module and you will see why chemistry can and should play an importantrole in your life. So, start and enjoy. What you are expected to learn After going through this module, you are expected to: 1. discuss how chemistry started; 2. explain its importance to human lives; 3. apply desirable qualities and scientific attitudes in solving problems encountered everyday; and 4. discuss the importance of scientific measurement.

How to learn from this moduleHere’s a simple guide for you in going about the module:1. Read and follow the instructions carefully.2. Answer the pretest in order to determine how much you know about the lessons in this module.3. Check your answers with the given answer key at the end of this module.4. Read each lesson and do all the activities that are provided for you.5. Perform all the activities diligently to help and guide you in understanding the topic.6. Take the self-tests after each lesson to determine how well you understood the topic.7. Answer the posttest to measure how much you have gained from the lessons. Good luck!What to do before (Pretest)Multiple Choice: Choose the letter of the best answer. Write the chosen letter on aseparate sheet of paper.1. The science that tackles the study of matter, its structure and the changes incomposition that matter undergoes isa. Astrology c. Ecologyb. Chemistry d. Physics2. When a chemist performs an experiment, the quantity that is being tested is thea. control c. theoryb. law d. variable3. Juan is comparing how many kilos of rice can be contained in a sack. What process ishe doing?a. counting c. measurementb. interpolation d. testing4. After making an observation and proposing a hypothesis, the next step that a scientistshould do is toa. form a conclusion c. analyze the data gatheredb. do another experiment d. state the conclusion -2-

5. A famous chemist has these words: “One may take it for granted that in every reactionthere is an equal quantity of matter before and after.” He was able to establish thescience of Modern Chemistry. Who was this famous chemist?a. John Dalton c. Robert Boyleb. Alexander Fleming d. Antoine Lavoisier6. Jack and Rose gather information using their five senses. What are they doing? a. stating their conclusion b. gathering data through observation c. formulating hypothesis based on the gathered data d. measuring the exact quantity compared to the other quantities7. The statement “Mercury is denser than water” is a ___________.a. law c. theoryb. fact d. problem8. During an experiment, one tries to form his/her theory as quickly as possible. Thisprocess is called _____________.a. data-gathering c. hypothesizingb. generalizing d. observing9. Which of the following statements is CORRECT? a. A scientist’s good characteristics include open-mindedness, honest, perseverance and curiosity. b. Only the most brilliant people like scientists can make discoveries c. Scientists must follow a strict plan in order to make a successful result d. All of the above10. In what manner is chemistry of immediate use to an agriculturist?a. in soil preparation c. in the use of soil fertilizerb. in the sowing technique d. in selecting what seed to plant11. A doctor performed several laboratory tests like X-ray, complete blood count, urinalysisand stool test on a patient. Which of the following steps in the scientific method did thedoctor do?a. making a generalization c. testing the hypothesisb. formulating a hypothesis d. identifying a problem12. Basically, chemistry deals with the study of the following EXCEPT:a. changes that matter undergoes c. properties of matterb. composition of matter d. forces13. How many significant figures are there in the measurement 9.0052 kg?a. 5 c. 7b. 6 d. 8 -3-

14. An appropriate metric unit to measure the distance from Manila to Jolo would be:a. meter c. kilometerb. centimeter d. nanometer15. The scientific method of solving a problem follows the sequence: a. hypothesize, conclude, experiment c. conclude, hypothesize, experiment b. hypothesize, experiment , conclude d. experiment, hypothesize, conclude16. The ratio of mass to volume is called c. density a. area d. temperature b. volume17. The number of digits by which a series of number is known with a degree of reliability iscalled:a. accuracy c. precisionb. parallax d. significant figures18. Discoveries are sometimes made through accident. This is calleda. invention c. serendipityb. innovation d. discovery by luck19. The system of measurement used by scientists around the world isa. British System c. Metric systemb. English System d. All of these20. Derived quantities are called such because they were based on the:a. SI units c. fundamental unitsb. secondary units d. formula21. What is the equivalent of -40°C in Fahrenheit scale?a. 32°F c. -32°Fb. 40°F d. -40°F22. The product of (2 x 103) and (3 x 103) is c. 6 x 104 a. 6 x 101 d. 6 x 106 b. 6 x 10323. Which of the following statements is TRUE about a scientific method? a. When results of an experiment do not fit the hypothesis, a scientist may ethically discard the results and repeat the experiment. b. The scientific method is a continuous process by which people learn about the physical universe. c. Scientists report the experimental results, but not the experimental design. d. People structure their lives on the principles of scientific method. -4-

24. Which equivalent factor does NOT describe a LITER?a. 1 Liter = 1000 cubic centimeters c. 1 Liter = 103 mLb. 1 gallon = 3.79 liters d. 1 Liter = 1 m325. The branch of science that deals with the study of matter, its structure and the changesin its composition isa. life science c. earth scienceb. chemistry d. physics Key to answers on page 27.Lesson 1. Chemistry: Its Beginning and Importance to Human Life Chemistry is a branch of science that helps us understand all forms of matter. Likeall other sciences, chemistry began in the prehistoric era and flourished in the modern time.Using the concepts, principles and skills in chemistry, this module will open our world to thewonders of the things that surround and affect us. What you will do Activity 1.1 Read this lesson and begin to understand how chemistry started and became thecentral science. The Origins of Chemistry: Where It All Began The earliest attempts to explain natural phenomena led to fanciful inventions – tomyths and fantasies – but not to understanding. Around 600 B.C., a group of Greek philosophers became dissatisfied with thesemyths. Stimulated by social and cultural changes as well as curiosity, they began to askquestions about the world around them. They were able to discover basic truths of natureby thinking things through experiments. The years between 600 B.C. and 400 B.C. arecalled the “Golden Age of Philosophy”. Some of the Greek philosophers believed they could find a single substance fromwhich everything else was made. Thales believed that it was water and Anaximenesthought it was air. Empedocles’ idea was that the universe is made of four elements namelyearth, air, fire and water. -5-

The period from 440 B.C and 420 B.C. was known as the age of atomism whenLeucippus and Democritus believed that matter was made of smallest particle which theycalled atom, a particle that could not be seen. Two thousand years later scientists provedthat this idea was true. Chemistry Today The Greek philosophers continued to search for truth and while they were studyingphilosophy and mathematics, the Egyptians were practicing the art of chemistry. They weremining and purifying the metals gold, silver and copper. They were making embalmingfluids and dyes. They called this art khemia. This Egyptian word became the Arabic wordalkhemia and then the English word alchemy. Alchemists tried to find the “philosopher’sstone”, a supposed cure for all diseases, and the “elixir of life” which would prolong lifeindefinitely. They failed in both attempts but along the way, they were able to discoveracetic acid, nitric acid, ethyl alcohol and other substances used by chemists today.Robert Boyle, The Forerunner of Modern Chemistry The modern age of Chemistry dawned in 1661 when Robert Boyle, an English chemist, published his book The Sceptical Chymist. His idea opposed the alchemists’ belief. Instead he proposed that scientists must start from basic principles and that theories about the world have to be proven by a series of experiment. He formulated the law relating volume and pressure. If Robert Boyle laid down the basic definition of an element, a French chemist Antoine Laurent Lavoisier laid down the basic definition for testing whether a substance fitted its definition.Antoine Lavosier, The Father of Modern Chemistry Innovative and scientific approaches paved the way for the rapid development of chemistry. In 1770, Antoine Lavoisier gained wide recognition when he refuted the then prevalent belief that water is converted into earth by repeated distillation. By carefully weighing both the earthy residue and the distilling apparatus, he demonstrated that the solid matter came from the glass vessels and not from the water. Speculating on the nature of the traditional four elements—earth, water, air, and fire, he began to investigate the role of air in combustion. On November 1, 1772, he stated that when burned sulfur and phosphorus increasedin weight because they absorbed “air”. On the other hand, the metallic lead formed when -6-

litharge was heated with charcoal weighed less than the original litharge because it had lost“air.” He gave phlogisticated air the name oxygen, or “acid producer” He explainedphlogiston theory as the result of the combination of the burning substance with oxygen.This theory was later revised and now known as the theory of combustion. On June 25,1783, he also explained that water was the product formed by the combination of hydrogenand oxygen. An English chemist named Henry Cavendish opposed this idea and later wasable to produce quantities of hydrogen, called “inflammable air,” by decomposing water intoits constituent gases. Because of Lavoisier’s findings, chemists tasted the first sound understanding of thenature of chemical reactions. His experiments paved the way for the flourishing of modernchemistry. Thus, he became known as the Father of modern chemistry.Time Line in Chemistry Date Person Event600 B.C.546 B.C Thales Idea that water is the main form of matter450 B.C. Anaximenes Idea that air is the main form of matter420 B.C. Empedocles Idea that the four elements – earth, air, fire 1661 1766 and water combine in different proportions 1775 1800 Leucippus and Idea of the atom or the Age of Atomism 1820 Democritus 1869 Robert Boyle The Sceptical Chymist 1886 H. Cavendish Discovery of hydrogen 1897 A. Lavoisier Discovery of the composition of air 1911 John Dalton Proposed the Atomic Theory 1913 John Jacob Devised the modern symbols of elements Berzelius Dmitri Periodic Law and designed the Modern Mendeleev Periodic Table of Elements Eugene Naming of cathode rays and discovery of Goldstein proton J.J. Thomson Proposed the structure of the atom; discovery of electron E. Rutherford Proposed the nuclear atom; discovery of a nucleus Niels Bohr Proposed the energy levels in atoms; Soon after, chemists like Joseph Priestly, John Dalton, Niels Bohr, Ernest Rutherford,the Curies and other scientists made new advancements in chemistry. Theseadvancements led to many distinct branches of chemistry. -7-

Branches of Chemistry During the 1700s and early 1800s, most chemists believed that there were two mainbranches of chemistry: organic and inorganic. These two branches still exist today,however, the rules governing their classification have changed.1. Organic Chemistry is the study of the compounds of carbon. This branch of chemistry is important to the petrochemical, pharmaceutical and textile industries. All living organisms have traces of carbon.2. Inorganic Chemistry is the study of chemical elements and their compounds except carbon.3. Other branches: a. Physical Chemistry deals with the relations between the physical properties of substances and their chemical formations along with their changes. b. Biochemistry is a science that fused biology and chemistry. It is concerned with the composition and chemical reactions that occur in the formation of living species. c. Analytical Chemistry deals mostly with the composition of substances. It seeks to improve means of measuring chemical composition of natural and artificial materials. In medicine, this is the basis for clinical laboratory tests for disease diagnosis. The nutritional value of the food we eat is determined through chemical analysis. Analytical chemists analyze many household products.Importance of Chemistry Chemistry plays a very important role in different areas of life. Some people viewchemistry as a very technical subject that deals with formulas and mind-bogglingcomputations. This may be true, but if you will try to look at things around you, you willbegin to appreciate its importance. The products of chemistry and technology are highlyuseful. For example, when you go to a beauty saloon and ask the hair stylist to straighten orcurl your hair, she/he needs to use a correct solution, or else it will not come out right.Chemistry also plays a very important role in medicine, engineering, agriculture,photography and other related fields. -8-

What you will doSelf-Test 1.1Match COLUMN A with COLUMN B.COLUMN A COLUMN B Pioneers of Chemistry1. started the age of atomism a. Empedocles2. proposed the phlogiston theory b. Leuccipus3. discovered hydrogen c. Anaximenes4. father of modern chemistry d. Henri cavendish5. forerunner of modern chemistry e. John Dalton6. believers of “false” chemistry f. Robert Boyle7. proposed the atomic theory g. Antoine Lavoisier8. wrote the Sceptical Chymist h. Alchemist Branches of Chemistry9. study of carbon and its compounds i. Organic Chemistry10. study of different chemical elements, its j. Inorganic Chemistry properties and structure11. study of the properties of substances and k. Physical Chemistry their chemical formations12. study of the chemical properties of l. Biochemistry substances particularly living organisms13. a branch of chemistry that is used as basis m. Analytical Chemistry for laboratory tests for disease diagnosis Chemistry Timeline14. “false” chemistry n. Between 600 B.C. and 400 B.C.15. Golden Age of philosophy o. alchemy Key to answers on page 27.Lesson 2. Desirable Qualities and Attitudes of Scientists The many wonders of chemistry have made it the central science. Whatdistinguishes science from the other fields of study is the way in which it seeks answers toquestions and the approach of scientists in solving problems. What are some of the characteristics and attitudes that chemists generally have incommon? Like us, chemists ask how and why things happen. However, unlike most of us, -9-

they are not satisfied with asking “why”. They always have possible solutions to a problem.They will not stop unless a problem is solved.Some Famous Filipino ChemistsDR. JULIAN A. BANZON A biophysical chemist who did the pioneering works on coconut as a source of chemicals and fuels. He devised the process of extracting residual coconut oil by chemical means rather than by physical meansDR. ALFREDO C. SANTOS He gained recognition for his researches DR. LOURDES J. CRUZ on natural products. He did a lot of work on alkaloids from indigenous medicinal plants. She has made significant contributions to the biochemistry of toxic peptides from venom of fish-hunting Conus marine snails. Her studies led to the biochemical characterization of active peptides from Conus venom and the development of conotoxins as biochemical probesDR. LUZ OLIVEROS-BELARDO A pharmaceutical chemist who worked on the chemistry of natural products and essential oils from most Philippines plants. Her works resulted in the production of new flavors and herbal medications. An organic chemist who is concerned with the properties of starch and protein and other grain constituents in relation to grain quality of rice.DR. BIENVENIDO O. JULIANO An organic chemist with an expertise on CLARA Y. LIM-SYLIANCO mutagens, anti-mutagens and bio-organic reactions. She has written numerous scientific articles, books, monographs and related materials. Some of her books published are used as textbooks in college chemistry. - 10 -

DR. SOLITA CAMARA-BESA A medical doctor by profession, she worked on sodium and potassium content of Philippine foods and established standards useful in the preparation of diets. Her analysis of cholesterol gave the Filipino the idea of the importance of diet especially on fats and cholesterol.Do the activity below to get a feel of how it is to be a chemist.What you will doActivity 2.1A. Perform this experiment designed for you:Materials: 2 jars with lid Set-up: 1 medicine dropper Medicine dropper 2 slices of breadProcedure:1. Put half a slice of bread into each jar. JAR 12. Moisten each half slice with ten drops of bread water.3. Cover the jars tightly. Keep one jar in sunlight JAR 2 and the other in a dark room or closet.4. Repeat procedures 1 and 3 in the other jar.5. Observe the jars daily for 1 week.6. Compare the results.7. Write your observations on the table.Observations: Day Jar 1 Jar 2 Jar 3 Jar 4SundayMondayTuesdayWednesdayThursdayFridaySaturday - 11 -

Analysis of Observations: ____________________________________________________________________ ____________________________________________________________________ ____________________________________________________________________ ____________________________________________________________________ ____________________________________________________________________ ____________________________________________________________________ ____________________________________________________________________ 1. What could be the problem in the experiment? ____________________________________________________________________ ____________________________________________________________________ 2. How will you answer the problem? ____________________________________________________________________ ____________________________________________________________________ 3. What are the implications of the experiment in your everyday living? ____________________________________________________________________ ____________________________________________________________________ ____________________________________________________________________ ____________________________________________________________________ Key to answers on page 28.B. How do scientists solve a particular problem in his/her experiment? The problem in the experiment was solved step by step. The step-by-step approachis what we call SCIENTIFIC METHOD. It is a systematic way of problem solving used byscientists. The basic steps in the scientific method are: 1. STATING THE PROBLEM – identifying or knowing what you want to investigate or study 2. GATHERING INFORMATION ON THE PROBLEM – jotting down important data or information gathered through observations 3. FORMING HYPOTHESIS – hypothesis is an educated guess. Forming this would help you find out what the answer to your problem might be. - 12 -

4. PERFORMING EXPERIMENTS TO TEST HYPOTHESIS – design and carry out an experiment to test your hypothesis. Observe everything you can. The smallest detail can sometimes be the most significant. 5. RECORDING AND ANALYZING DATA – interpret and evaluate the information gathered. Do calculations if needed to come up with your conclusion 6. STATING A CONCLUSION – this answers the problem stated. If the problem is still unsolved, try a new approach or perform another experiment. Repeat the steps from the beginning until a solution may become clear. Scientists run an experiment setup and a control setup to make sure the results ofthe experiment were caused by the variable and not by some hidden factors. Try this activity and identify the different science processes. What you will do Activity 2.21. Examine the picture below. What can you say about Picture A and Picture B?PICTURE A PICTURE B_________________________________ __________________________________________________________________ _________________________________What made you say so?____________________________________________________________________________________________________________________________________________2. The pictures on the next page show a boy who is using a colored shampoo. Which of the following pictures implies observation, inference, hypothesis and prediction? - 13 -

A B CDThe boy says: _____________________ _____________________Picture A: “My shampoo is purple.“ _____________________Picture B: “Purple? Someone must have _____________________ added color to my shampoo.” Key to answers on page 28.Picture C: “The color of the shampoo doesn’t change hair color.”Picture D: “ Water will wash away all purple color in my hair.” Discoveries in science sometimes occur by luck or by accident. This is calledSERENDIPITY. What you will do Self-Test 2.1Analyze the following situations and answer the questions that follow. Rachel was doing an experiment. She placed a piece of orange peel in each of thetwo jars. She added 3 milliliters of water to jar 1 and placed it in the refrigerator. She addedno water to jar 2 and placed it on a windowsill in the kitchen. By the end of the week, shenoticed more mold growth in jar 2. She concluded that light, warm temperature, and nomoisture were ideal conditions for mold growth.1. What was Rachel’s problem? ______________________________________________________________________ ______________________________________________________________________ - 14 -

2. What were her observations? ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________3. How did she check her observations? ______________________________________________________________________ ______________________________________________________________________4. What was her conclusion? ______________________________________________________________________ ______________________________________________________________________5. Can you say that Rachel’s conclusion was correct? Why or why not? ______________________________________________________________________ ______________________________________________________________________ Key to answers on page 28.Lesson 3. Scientific Measurement Chemistry is an experimental and a quantitative science. The development of itsprinciples is based on carefully designed experiments carried out under controlledconditions. At the heart of any quantitative experiment in our surroundings and in laboratories isthe performance of operations called measurements. Measurements are made nearlyeveryday, not only in the laboratory but in every establishment and even at home. This lesson will take you to the world of scientificmeasurements. Read this lesson and learn to appreciateits importance.METRIC – The Universal Language of ScientificMeasurement Measurement is the process of comparing a known quantity like a measuring device to an unknown quantity or the things or objects to be measured. It is the process of determining how many times a certain quantity is contained in a standard measuring device. - 15 -

 The scientific system of measurement is called the metric system. The metric system is often referred to as the International System of Units, or SI. Scientists throughout the world use the metric system of measurement. The two subdivisions of the metric system are the mks (meter-kilogram-second) and cgs (centimeter-gram-second). It is based on units of ten. SI consists of three classes of units that form coherent set base units, derived units and supplementary units. There are seven basic or fundamental units considered in the SI. Fundamental Quantities are quantities that can be measured directly using measuring devices. Basic Types of Physical Quantities 1. Mass (m) is a basic property of matter. It is the measure of the amount of matter it contains. The standard unit of mass is the kilogram, kg. One kilogram (kg) is the mass of 1 liter (L) of water at 4°C and a pressure of 1 atmosphere (atm). The mass of an object remains the same even if the position of the object is changed with reference to the earth’s center. It is measured using the triple beam balance or the equal arm balance. 2. Length (l) is a distance between two distinct points. It is measured by using a metric ruler. Width (w) is also a length, and height (h), is the vertical distance. The basic unit is the meter (m). 3. Time (t) is the regular interval between two successive points. The standard unit of time is the second. The second was originally defined in terms of the motion of the earth, but it was revised and instead compared to vibrations of cesium atoms. 4. Temperature (T) is the measure of the hotness or coldness of an object. It is technically defined as the measure of the average kinetic energy of a body. Kelvin (K) is used as the basic unit. 5. Electric current (I) is the measure of the flow of electrons or charges. An ammeter is used to measure current expressed as Ampere (A). 6. Luminous intensity (E) is the amount of illumination received by an object. The unit of measure used to describe this is candela (cd). 7. Amount of substance (n) is the number of moles. The basic unit is the mole or mol. The different units of measurements are used in our day-to-day activities. When yougo the gas station to fill up your gas tank, the unit of measurement used is liter. In the sari-sari store or supermarket, the units used for mass are grams and kilograms. For volume,milliliters or liters are used. On road markers, the distances are measured in kilometers. The most common measurements you will be using in the laboratory are those oflength, mass, volume and temperature. - 16 -

The Common Metric Units Length Mass1 meter, m = 100 centimeters, cm 1 kilogram, kg = 1 000 grams, g1 meter, m = 1000 millimeters, mm 1 gram, g = 1000 milligrams, mg1 meter, m = 1000 000 micrometers, µm 1000 kilograms, kg = 1 metric ton1000 meters, m = 1 kilometer, km Volume Temperature1 Liter, L = 1000 milliliters, mL °C = 5/9(°F – 32) or1 Liter, L = 1000 cubic centimeter, cc °C = (°F – 32)/ 1.8 °F = 9/5(°C) +32 or °F = 1.8(°C) +32 Kelvin, K = °C + 273The Table of Prefixes Prefix Symbol Powers of Ten ExampleDeci d decimeter, dmCenti c 0.1 =10-1 centimeter, cmMilli m milligram, mgMicro µ 0.01 =10-2 microgram, µg n nanometer, nmNano da 0.001 =10-3 dekagram, dagDeka h hectometer, hmHecto k 0.000001 =10-6 kilogram, kgKilo M Megagram, MgMega G 0.000000001 =10-9 Gigameter, GmGiga 101 = 10 102 = 100 103 = 1 000 106 = 1 000 000 109 = 1 000 000 000Metric – English Equivalents Metric English 1 Liter, L 1.06 quartz, qt. 250 milliliter, mL 1 cup, c 1 kilogram, kg 2.2 pounds, lb. 28.3 grams, g 1 ounce, oz. 3.79 Liters, L 1 gallon, gal. - 17 -

What you will doActivity 3.1 ConversionStudy the examples.1. Convert 75 millimeters (mm) to its corresponding length ina. meters b. centimeters c. kilometersSolution: a. 75 mm × 1m = 75 m = 0.075 m 1000 mm 1000 b. 0.075 m × 100 cm = 0.075 × 100 cm = 7.5 cm 1m c. 7.5 cm × 1m × 1km = 7.5 km = 0.000075 m 100 cm 1000 m 100 0002. Change 430 milligrams to grams From the Table of Prefixes , milli = 10-3 Change the powers of ten to a prefix. 430 x 10-3 grams By the use of scientific notation, it would be 4.30 x 102 x 10-3 The final answer is 4.30 x 10-13. 5 gallons of mineral is equivalent to how many liters? 5 gallons × 3.79 Liters = 18.95 liters gallon4. 2 x 109 bytes is equal to 2 Gigabytes or 20 Gb5. The normal body temperature is 37°C. What is its equivalent in °F and K? Formula: °C = 5 (°F - 32) or °C = (°F - 32) 9 1.8 °F = 9 (°C + 32) or °F = 1.8 (°C) + 32 5 Kelvin, K = °C + 273 Solution: °F = 9 (37°C) + 32 = 1.8 (37°C + 32) = 66.6 + 32 = 98.6 °F 5 K = °C + 273 = 376 - 18 -

or 98°F is equal to ____°C°C = 5 (°F - 32) or °C = (°F - 32) 9 1.8°C = 5 (98 - 32) or °C = (98 - 32) 9 1.8 = 66 1.8 = 36.67 °C6. The density of water in the cgs is 1 g/cm3. What is its density in mks?1g × (100cm)3 × 1kg = 1g × (102 cm)3 × 1kgcm3 1m3 1000 g cm3 1m3 103 g = 1g × 106 cm3 × 1kg cm3 1m3 103 g = 106 kg 103 m3 = 103 kg or 1000 kg m3 m3 SCIENTIFIC NOTATION is a compact, simple and easy way of writing down verysmall and very large numbers using powers of ten. The exponent tells the number of timesthe decimal point is moved from its original place to the right or from the original place to theleft. The exponent is NEGATIVE if the decimal point is moved from left to right andPOSITIVE if it is moved from right to left. Example: = 4.0 x 106 1. 4 000 000 = 5.32 x 108 2. 532 000 000 = 4.5 x 10-8 3. 0.000000045 = 3.2 x 10-3 4. 0.00321. `To add and subtract numbers expressed in powers of ten, simply copy the common exponent and proceed as in addition or subtraction. (If the exponents are not the same, make them the same first before adding or subtracting)Add: (1.3 x 102) + (2.4 x 102) = 3.7 x 102 (4.0 x 103) – (2.3 x 102) = 1.7 x 102 (5.2 x 105) + (1.3 x 104) = - 19 -

(First make the exponent the same, then add the numbers and copy the common exponent.) (5.2 x 105) + (0.13 x105) = 5.33 x 1052. To multiply numbers expressed in powers of ten, add the exponents. If the exponents are of different signs, meaning, one is positive and the other one is negative, add them algebraically by subtracting the smaller number from the larger number and copying the sign of the larger number. (2.5 x 105) • (4.3 x 103) = 10.75 x 108 = 1.075 x 108+1 = 1.075 x 109 Final answer should be expressed in standard form. M.N x 10n, where M is the only digit before the decimal point, N is/are the number(s) after the decimal point, and n is the exponent. (2.5 x 105) • (4.3 x 10-3) = 10.75 x 102 = 1.075 x 103 (2.5 x 10-5) • (4.3 x 103) = 10.75 x 10-2 = 1.075 x 10-13. To divide numbers expressed in powers of ten, subtract the exponents. If the exponents are of different signs, meaning, one is positive and the other one is negative, change the sign of the number to be subtracted and then proceed as in addition. 4.3 x 105 = 1.72 x 105 – 3 = 1.72 x 102 2.5 x103 4.3 x 10-5 = 1.72 x 10-5 – 3 = 1.72 x 10-8 2.5 x103 4.3 x 105 = 1.72 x 10-5 – 3 = 1.72 x 10-8 2.5 x10-3Parallax - is the apparent shift in position of an object as it is viewed or observed at differentangles.Accuracy and Precision Accuracy is a degree of agreement between a measured value and the true value. Precision is the degree of the instrument’s exactness.Significant figures – the number of digits or figures that best represents the value of ameasurement. - 20 -

Rules in Determining the Number of Significant Figures:  All non-zero digits are significant. (1, 2, 3, 4, 5, 6, 7, 8, 9)  All zeros in between two non-zero digits are significant. 2804 has four (4) significant figures.  All zeros to the right of a decimal point but to the left of a non-zero digit are NOT significant. For example, 0.0003068 has four (4) significant figures  All zeros to the right of non-zero digit without an expressed decimal point following it are NOT significant. For example, 406,000 has three (3) significant figures, but 406,000. has six (6) significant figures because of the indicated decimal point.Graph - is a tool or mechanism to show the relationship between two variables. The twokinds of variables are the dependent variables plotted on the Y-axis or the ordinate andthe independent variables plotted on the X-axis or the abscissa.What you will doSelf-Test 3.1Direction: Do the indicated operation.1. A block of iron is 5.0 cm long, 3.0 cm high and 4.0 cm wide weighs 474 g. What is the density of the iron?2. The density of alcohol is 0.8 g/cm3. Calculate the volume of 1.6 kg of alcohol.3. Convert the following units: a. 1.2 L to gallons to quartz b. 4.17 kg to grams to decigrams c. 40°C to °F4. Indicate the number of significant figures: a. 2 546 000 000 b. 0.00000000150 c. 0.000030075. a. (3.6 x 104) / (4 x 10-6) b. (2.3 x 10-5) • (3.0 x 108) Key to answers on page 28. - 21 -

Let’s Summarize1. Pure science involves gathering information or the discovery of a pattern. When that information is applied to some use, it becomes technology. Chemistry is a central science that deals with the composition of matter, its structure and the changes in composition that this matter undergoes.2. Branches of Chemistry a. Organic Chemistry is the study of the compounds of carbon. This branch of chemistry is important to the petrochemical, pharmaceutical and textile industries. All living organisms have traces of carbon. b. Inorganic Chemistry is the study of chemical elements and their compounds except carbon. c. Other branches:  Physical Chemistry deals with the relations between the physical properties of substances and their chemical formations along with their changes.  Biochemistry is a science that is concerned with the composition and changes in the formation of living species.  Analytical Chemistry deals mostly with the composition of substances. It seeks to improve means of measuring chemical composition of natural and artificial materials. In medicine, this is the basis for clinical laboratory tests for disease diagnosis. The nutritional value of the food we eat is determined through chemical analysis. Analytical chemists analyze many household products.3. Origin of Chemistry a. Age of Alchemy – the chemistry of mining and purifying the metals gold, silver and copper. This art is called khemia. This Egyptian word became the Arabic word alkhemia and then the English word alchemy. b. Age of atomism when Leucippus and Democritus believed that matter was made of smallest particle which they called atom, a particle that could not be seen. c. Modern Chemistry – the stage when Antoine Lavoisier proposed the phlogiston theory as the result of the combination of the burning substance with oxygen. This theory was later revised and now known as the theory of combustion.4. A problem is a situation that seems to be missing some information.5. Solving problems involves looking for patterns, making predictions, and testing the predictions. An approach to problem solving used by chemists is called the scientific method.6. Scientific Method is a systematic approach consisting of the following basic steps: - 22 -

a. Stating the Problem – identifying or knowing what you want to investigate or study b. Gathering Information on the Problem – jotting down important data or information gathered through observations c. Forming Hypothesis – hypothesis is an educated guess. Forming this would help you find out what the answer to your problem might be. d. Performing Experiments to Test Hypothesis – designing and carrying out an experiment to test your hypothesis. Observe everything you can. The smallest detail can sometimes be the most significant. An experiment is an organized procedure for testing a hypothesis. e. Recording and Analyzing Data – interpreting and evaluating the information gathered. Do calculations if needed to come up with your conclusion f. Stating a Conclusion – this answers the problem stated. If the problem is still unsolved, try a new approach or perform another experiment. Repeat the steps from the beginning until a solution may become clear.7. A hypothesis is testable prediction.8. A theory, based on many observations, is the most logical explanation of why things work.9. A scientific fact is a summary of many experimental results that describes a pattern in nature.10. A standard of measurement is an exact quantity that people agree to use as a basis of comparison.11. When a standard measurement is established, all measurements are compared to the same exact quantity – the standard. SI BASE UNITS / FUNDAMENTAL QUANTITIESQuantity Measured Unit SymbolLength meter mMass kilogram kgTime second sElectric current Ampere ATemperature Kelvin KAmount of substance Mole molLuminous Intensity candela cd12. In International Systems of units, SI, prefixes are used to make the base units larger or smaller by powers of ten. - 23 -

Prefix Symbol Powers of Ten ExampleDeci d decimeter, dmCenti c 0.1 =10-1 centimeter, cmMilli m milligram, mgMicro µ 0.01 =10-2 microgram, µg n nanometer, nmNano da 0.001 =10-3 dekagram, dagDeka h hectometer, hmHecto k 0.000001 =10-6 kilogram, kgKilo M Megagram, MgMega G 0.000000001 =10-9 Gigameter, GmGiga 101 = 10 102 = 100 103 = 1000 106 = 1000 000 109 = 1000 000 00013. Scientific Notation is a compact, simple and easy way of writing down very small and very large numbers using powers of ten.14. Significant figures – the number of digits or figures that best represents the value of a measurement. Rules in determining the Number of Significant Figures: a. All non-zero digits are significant. (1, 2, 3, 4 , 5, 6, 7, 8, 9) b. All zeros in between two non-zero digits are significant. 2804 has four (4) significant figures. c. All zeros to the right of a decimal point but to the left of a non-zero digit are NOT significant. For example, 0.0003068 has four (4) significant figures. d. All zeros to the right of non-zero digit without an expressed decimal point following it are NOT significant. For example, 406 000 has three (3) significant figures, but 406 000 has six (6) significant figures because of the indicated decimal point.15. Graph - is a tool or mechanism to show the relationship between two variables. The two kinds of variables are the dependent variables plotted on the Y-axis or the ordinate and the independent variables plotted on the X-axis or the abscissa.PosttestMultiple Choice. Choose the letter of the best answer. Write the chosen letter on aseparate sheet of paper.1. Which refers to a step-by-step approach of a scientist in solving a problem?a. conclusion c. hypothesisb. experiment d. scientific method - 24 -

2. The boiling point of water is 100°C. What is its equivalent in Fahrenheit scale?a. 312 c. 100b. 212 d. 323. The sides of a rectangle are 8 cm and 4 cm. Its area isa. 16 cm2 c. 64 cm2b. 32 cm2 d. 128 cm24. The basic unit of mass in the metric system is thea. kilogram c. gramb. kilometer d. meter5. A meaningful measurement must have c. a number and a unit a. a number only d. a prefix and a unit b. a unit only6. Gram/milliliter s a unit used to express c. density a. area d. temperature b. mass7. The product of (4 x 103) and (9 x 103) is c. 2.6 x 105 a. 6 x 101 d. 3.6 x 107 b. 1.6 x 1048. Which of the following equations shows an inverse relationship?a. A = kB c. k = A/Bb. k = AB d. B = kA9. In nature, if one variable decreases as another variable increase, the relationshipbetween the two variables is said to bea. vectors c. directb. inverse d. inverse square10. A skill developed by performing laboratory investigations and observations isa. using and manipulating equipment c. working cooperativelyb. making observations d. All of these11. The amount of space an object takes up is itsa. mass c. weightb. pressure d. volume12. The quotient of 66.0 x 105 and 3 x 108 is c. 2.2 x 105 a. 22 x 1011 d. 2.2 x 10-2 b. 22 x 10-5 - 25 -

13. Which of the following steps is NOT a part of scientific method? a. Recognize a problem. b. Perform experiments to test predictions. c. Make a guess about the answer and form your conclusion. d. Repeat the experiments until the answers match the predictions.14. Which best describes a scientific fact? a. something you believe is true because a friend told you about it b. an educated guess that has yet to be proven by experiment c. a synthesis of collection of data that includes well-tested guesses d. a prediction that has been tested over and over again and always found to be true15. Which best defines a hypothesis? a. the long side of a right triangle b. an educated guess that has yet to be proven by experiment c. a synthesis of collection of data that includes well-tested guesses d. a guess that has been tested over and over again and always found to be true16. Which statement is TRUE about a theory? a. It is a science story about atoms and molecules. b. It is an educated guess that has yet to be proven. c. It is a synthesis of large collection of information with well-tested guesses. d. It is an agreement among competent observers of the same phenomena.17. A metal block measuring 25 cm x 10 cm x 0.05 cm has a mass of 13.50 kg. What is itsdensity in g/cm3?a. 0. 108 c. 10.8b. 1.08 d. 10818. The pressure of a given gas increases as its temperature increases. When plotted what will be the shape of the line graph? a. b. c. d. Y YY Y XXXX19. The number .00045700 has _____ significant figures.a. 8 c. 6b. 7 d. 520. Antoine Lavoisier was known as the c. Advocate of “False” Chemistry a. Forerunner of Chemistry d. Proponent of the Age of Atomism b. Father of Modern Chemistry - 26 -

21. Rizza is 5 feet and 2 inches tall. What is her height in meters?a. 1 c. 1.57b. 1.5 d. 1.5922. The __________ describe(s) the steps followed in conducting an experiment.a. conclusion c. problemb. data d. procedure23. The SI prefix that means 1/1000 is c. milli- a. centi- d. nano- b. kilo-24. The symbol µg is read as c. milligram a. kilogram d. nanogram b. microgram25. Which of the following is NOT a derived unit?a. meter c. square meterb. cubic centimeter d. grams per milliliter Key to answers on page 29.Key to AnswersPretest 6. b 11. d 16. c 21. d 7. b 12. d 17. d 22. d 1. c 8. c 13. a 18. c 23. b 2. b 9. a 14. c 19. c 24. d 3. c 10. c 15. b 20. c 25. b 4. c 5. d 6. h 11. k 7. e 12. lLesson 1 8. f 13. m 9. i 14. oSelf-Test 1.1 10. j 15. n 1. b - 27 - 2. g 3. d 4. g 5. f

Lesson 2Activity 2.1Possible Answers1. Problem: What are the common factors affecting reactions?2. Follow the steps in scientific method.3. There are factors that affect the reactions like light and moistureActivity 2.21. Picture A – shows that she feels hot (Look at the barometer reading inPicture B – shows that she feels cold both pictures)2. Picture A – observationPicture B – inference or formation of hypothesisPicture C – predictionPicture D – experimentation or testing the hypothesisSelf-Test 2.11. What are the conditions ideal for mold growth?2. That there were more mold growth in jar 2.3. She compared her results with jar 1.4. She concluded that light, warm temperature and no moisture were ideal conditions for mold growth.5. Yes, because it was stated in her observationsLesson 3Self-Test 3.11. Given: m = 474 g l = 5.0 cm w = 4.0 cm h = 3.0 cm Compute for the Volume, V = l x w x h = 60 cm3Find: Density of the woodFormula:D=m VD = 474 g = 7.9 g 60 cm3 cm3 - 28 -

2. Given: D = 0.8 g/cm3 m = 1.6 kg = 1600 g Find: Volume Formula: D = m or V = m VD V = 1600 g g 0.8 cm3 V = 2000 cm33. a. 1.2 L to gallons 1.2 L × 1gal = 0.3166 gal 3.79 L 1.2 L to quartz 1.2 L × 1.06 qt = 1.272 qt 1L b. 4.17 kg = 4.17 × 103 g = 4170 g × 10-1 dg = 417 decigrams or 417 dg 1g c. 40°C to °F °F = 9 (°C) + 32 = 9 (40°C) + 32 = 72 + 32 = 104°F 554. a. 4 b. 3 c. 45. a. 7.5 x 10-9 b. 6.9 x 103Posttest1. d 6. c 11. d 16. d 21. c2. b 7. d 12. d 17. d 22. d3. b 8. b 13. c 18. d 23. c4. a 9. b 14. d 19. d 24. b5. c 10. d 15. b 20. b 25. a - 29 -

ReferencesHagad, R.H. (2003). Chemistry. Quezon City, Philippines: ALCO Printers.Lemay, E.H & Beall, H. (2002). Chemistry in the changing world. Glenview, USA: Prentice Hall.Mendoza, E. & Religioso, T, (2001). Chemistry. Quezon City, Philippines: SIBS Publishing.Nueva España, R.C. & Apostol, J, (2004), Chemistry. Quezon City, Philippines: Abiva Publishing.Oxtoby, D.W. & Freeman, W.A. (1998). Chemistry: The science of change. CA: Saunders College Publishing. - 30 -

Module 2Laboratory Apparatus, Safety Rules and Symbols What this module is about The first module let you go through sample activities of scientists to develop yourscience processes and skills. This time, you will experience how chemists work in alaboratory with different apparatus on hand and how to take laboratory precautions. The activities in this module will teach you how to use different apparatus in thelaboratory. It will also develop your skills in making accurate measurements using thecommon laboratory equipment, in using them safely, and in interpreting icons and symbolsused in a laboratory. This module contains the following lessons:  Lesson 1 – Identifying Laboratory Apparatus and Their Uses  Lesson 2 – Laboratory Safety Precautions  Lesson 3 – Laboratory Safety Symbols So let’s start. Just read and follow the instructions in this module. Good luck andhave fun! What you are expected to learn After going through this module you are expected to: 1. classify different laboratory apparatus based on their uses; 2. identify the laboratory icons and symbols used inside a laboratory; and 3. state different precautionary measures in the laboratory to be observed. How to learn from this module Here’s a simple guide for you in going about the module:

1. Take your time in reading the instructions.2. Follow the instructions very carefully.3. Before working on the activities, answer the 20-item pretest honestly in order to determine how much you know about the topics discussed in this module.4. Check your answers with the given answer key.5. Perform all the activities diligently to help you understand the topics.6. Take the self-tests after each lesson.7. Answer the posttest.What to do before (Pretest)Multiple Choice. Choose the letter of the best answer. Write the chosen letter on aseparate sheet of paper. Be honest in answering the questions.1. Suppose your brother accidentally cut his finger with a broken glass. What will you do? a. Continue with what you’re doing. b. Call your mother and tell her what happened. c. As first aid, put a medicated plaster around his finger. d. Call the attention of your neighborhood about what happened.2. While reading the procedure of an activity, you happen to come across this icon. What does it mean? a. It’s a toy. b. It’s a trademark sign. c. It’s a sign of an electrician. d. It’s a sign that you will be using electricity in the activity.3. Given the following laboratory apparatus: graduated cylinder, reagent bottle, test tubeand watch glass. Which will you use to get the volume of water?a. test tube c. graduated cylinderb. watch glass d. reagent bottle4. You are asked by your teacher to get the mass of a piece of stone that will be used in anexperiment. What apparatus will you use?a. florence flask c. graduated cylinderb. erlenmeyer flask d. triple beam balance5. You have come across this icon. What does this mean? a. It is poisonous. c. It is a metal. b. It is radioactive. d. It is a nonmetal. -2-

6. In an experiment you are asked to determine the volume of the stone. How are you going to do it given a 100 mL graduated cylinder alone? a. Fill the graduated cylinder with 50 mL water and place the stone in it. The rise in the level of the water is the volume of the stone. b. Fill the graduated cylinder with water up to the brim and place the stone in it. c. Put the stone inside the graduated cylinder. d. All of the above7. Which of the following is NOT in the group of apparatus that are used in storing liquids?a. beaker c. graduated cylinderb. florence flask d. reagent bottle8. Which of these apparatus will you use if you want to measure the density of a certain liquid? a. beaker and test tube b. beaker and graduated cylinder c. test tube and platform balance d. graduated cylinder and triple beam balance9. What will you use to transfer a liquid into a small-mouthed bottle without spilling?a. a funnel c. a test tubeb. a petri dish d. a graduated cylinder10. If Bunsen burner is not available for an experiment, what can be used as replacement forthe Bunsen burner?a. a candle c. an alcohol burnerb. a gas stove d. a long and thick thread11. What will you use if you want to fill a narrow-mouthed bottle with liquid?a. burette c. glass tubingb. funnel d. pipette12. What can you use to avoid breakage when heating a glassware?a. clay triangle c. watch glassb. iron ring d. wire gauze13. When using a triple beam balance, what should you remember before weighing anything? a. Check if the pan is free from dust. b. Always check the poises on the beam. c. Always check if the pointer is set to zero. d. Adjust the poise one at a time from zero to attain 100% accuracy.14. One of the most important safety rules is to: a. avoid heating objects. b. read the procedure of the activity. -3-

c. follow your classmates’ directions.d. read the instructions and follow them carefully.15. In boiling 10 mL of water using a test tube, what is the proper way of holding the test tube when you’re working with somebody in a laboratory? a. Keep it away from anybody else inside the laboratory. b. Let the test tube face someone as it is being heated. c. Hold it directly above the flame. d. All of the above16. When doing an experiment like heating or anything that uses fire, what should you beready with?a. an apron c. a pail of waterb. a damp cloth d. a wet tissue paper17. Which of the following symbols suggests that you are working with glassware in a laboratory? a. b. c. d.18. Which of the following statements about electrical safety is NOT correct? a. Use proper extension cords to plug any electrical device. b. Touch an electrical device with wet and clean hands. c. Never plug too many electrical devices in only one outlet. d. Always use extension cords with multiple sockets.19. A safety symbol in the shape of a flask alerts you toa. be careful with lab animals c. wear heat resistant glovesb. be careful with glassware d. wear safety goggles20. A triple beam balance measuresa. area b. mass c. pressure d. volume Key to answers on page 27.Lesson 1. Identifying Laboratory Apparatus and Its Uses When you think of chemists at work, you probably imagine them in a modernlaboratory with test tubes, other delicate instruments, apparatus, and bottles of strangesubstances. -4-

You’re right! In the laboratory, you can find different laboratory apparatus. TheScience laboratory is a place of adventure and discovery. Some of the most exciting eventsin scientific history have happened in the laboratory. The discovery of the atoms, theproduction of plastics for clothing, the analysis of chemicals of substances, and otherdiscoveries were first made by chemists in a laboratory. But all these things could neverhave happened if there were no equipment and devices. Different laboratory apparatusserved their purposes. Here are some of the laboratory equipment and their uses. What you will do Activity 1.1 Study the different apparatus grouped in each box. They are grouped according totheir uses. Group I: Some apparatus used for STORING LIQUIDS Beaker Reagent bottles Florence Flaska deep wide mouthed, a vessel used to contain a round, flat-bottomed,thin-walled, cylindrical chemicals that are mixed long necked vessel usedvessel with a pouring lip or added with other to measure largeused to measure large substances to bring about quantities of liquid and toquantities of liquid; can chemical reactions to form hold boiling liquidsalso be used to store or new substances orcontain liquid mixtures compounds. -5-

Group I: Some apparatus used for STORING LIQUIDS Erlenmeyer Flask Volumetric Flask Test Tubes in a Racka cone-shaped vessel a flat-bottom vessel with small, glass-tube shapedwith a narrow flat bottom long neck container used containers that are closedused to measure volume to store liquids or solutions and round at the bottomof liquid; also serves as for observation; can also with open end used toreceiver and stores be used to measure mix, heat and store smallliquid that is to be kept volume of volatile liquids amounts of liquids andfor further analysis substances.Group II: Some apparatus used for MEASURING VOLUME Graduated Cylinder Pipette & Burette Medicine Droppera narrow cylindrical Pipette - used to transfer a small glass or plasticvessel used to measure small amount of liquid of tube with rubber bulb atthe volume of liquids and known volume to another one end that is used tothe volume of irregular container suck up liquid and releasesolids by water Burette - a glass tube with it one drop at a timedisplacement measurements marked on the side and a stopcock at the bottom, used to accurately measure the volume of liquid before releasing it in another container. -6-

Group III: Apparatus used when HEATING SUBSTANCES Wire Gauze Iron Ring Iron Clampused to protectglassware during the used as base to hold the used to hold the testheating process. the wire gauze and any other tube, distilling flask, and container to be heated other apparatus to be heated Iron Stand Bunsen Burner Clay Triangle Supports the crucible onsupports the iron ring A burner that produces hot an iron ring when heatingand iron clamp during flame by mixing flammableheating, distillation and gas under pressureother extraction through controlledpurposes quantities of air. Crucible Tong Crucible and cover Evaporating Disha tool used to hold hot a heat resistant containermaterials or apparatus with cover in which ores or a shallow heat resistant materials are melted porcelain dish in which a solution is heated and allowed to evaporate leaving a residue on its plate -7-

Group IV: OTHER LABORATORY APPARATUS Watch Glass Test Tube Brush Test Tube HolderA rounded-bottom circular Used to clean small- Holds the test tube whileplate where chemical mouthed containers like heating or during anreactions are being test-tubes experimentobserved Spatula Funnel Mortar and Pestlea shallow round crystal or a cone-shaped tool with Used to grind, poundglass dish used to hold large opening at the top and mash solidsmall amounts of and a small opening or substances into powdersubstances to be tested tube at the bottom used to formfor a reaction guide liquids and other substances through a small opening; used to hold filter paper during filtration What you will do Self-Test 1.1Matching Type: Shown in Column A are the drawings of some common laboratoryapparatus listed. In Column B you will find the uses of these apparatus. Draw a line thatconnects the apparatus to its use. COLUMN A COLUMN BAPPARATUS USES -8-

1. A. used to hold small amount of liquid solution for testing2. B. used to clean test tubes or glassware with narrow opening3. C. used to measure the volume of liquid4. D. used to allow a heated liquid solution to evaporate leaving a residue on its place5. E. used to measure the mass of an object6. F. used to hold liquid / solution to be tested7. G. used to hold hot materials COLUMN A COLUMN BAPPARATUS USES -9-

8. H. used as container of substances for testing if there is a chemical reaction9. I. used to measure the hotness and coldness of an object10. J. used to guide liquids when pouring or transferring into a small tube container11. K. used to pulverize solid materials to powder form12. L. used as container of liquids or reagent ready for testing or experiment13. M. used to contain liquids or solution in large amount14. N. a tool where ore or materials are melted15. O. used to heat substances Key to answers on page 27.What you will doActivity 1.2 Double-Pan and Triple Beam Balances: Measurement of Mass - 10 -

The laboratory balance is an important tool in scientific investigations. You can usethe balance to determine the mass of materials. Different kinds of balances are used in thelaboratory. One kind of balance is the double-pan balance. Another kind is the triple-beambalance. To use the balance properly, you should learn the parts, function and location ofeach part of the balance you want to use. Here are the two kinds of balances. Study their parts and functions:Parts of a Double-Pan Balance and Their Functions 1. Pointer – used to determine when the mass being measured is balanced by the riders or masses of the balance 2. Scale – series of marks along which the pointer moves. 3. Zero point – center line of the scale to which the pointer moves when the mass being measured is balanced by the riders or masses of the balance 4. Adjustment knob – knob used to set the balance at the zero point when the riders are all on zero and no masses are on either pan 5. Left pan – platform on which an object whose mass is to be determined is placed 6. Right pan – platform on which standard masses are placed. 7. Beams – horizontal strips of metals on which marks or graduations appear that indicate grams or parts of grams 8. Riders – devices that are moved along the beams and used to balance the object being measured to determine its mass 9. Stand – support for the balance.How to Use the Double-Pan or the Platform Balance As the name implies, the double beam or platform balance has two beams. The - 11 -

beams are calibrated or marked in grams. The upper beam is divided into ten major units of1 gram each. Each of these units is further divided into units of 1/10 of a gram. The lowerbeam is equal to 10 grams. The lower beam can be used to find the masses of the objectsup to 200 grams. Each beam has a rider that is moved to the right along the beam. Therider indicates the number of grams needed to balance the object in the left pan. Before using the balance, be sure that the pans are empty and both riders are set tozero. If your pointer does not read zero, slowly turn the adjustment knob so that the pointerdoes read zero. The following procedure can be used to find the mass of an object using the double-pan balance: 1. Place the object whose mass is to be determined on the left pan. 2. Place the standard masses on the right pan. 3. Be sure that the pointer indicator should be at zero, meaning, the left pan and the right pans are balanced. 4. Count the number of standard masses. Its equivalent is equal to the mass of the objects weighed. The triple beam balance is a single-pan balance with three beams calibrated ingrams. The front beam or 100-gram beam is divided into ten units of ten grams each. Themiddle or 500-gram beam is divided into five units of 100 grams each. The back beam or10-gram beam is divided into 10 major units of 1 gram each. The following steps can used to find the mass of an object using a triple beambalance: 1. Place the object to be weighed on the pan. 2. Move the rider on the middle beam notch by notch until the horizontal pointer drops below zero. Move the rider back to one notch. - 12 -

3. Move the rider on the front beam notch by notch until the pointer again drops below zero. Move the rider back to one notch. 4. Slowly slide the rider along the back beam until the pointer stops at the zero point. 5. The mass of the object is equal to the sum of the readings on the three beams. What you will do Self-Test 1.2Fill in the blank with a word or phrase that best completes the statement.1. In using a double-pan balance, the object to be weighed is placed on _______________.2. In using the triple beam balance, the mass of the object is _______________.3. _______________ is the knob used to set the balance at the zero point when the riders are all on zero and no masses are on either pan.4. The horizontal strips of metals on which marks or graduations appear that indicate grams or parts of grams is called the _______________.5. In using a double-pan balance, the equivalent mass of the object is placed on _______________. Key to answers on page 27.Lesson 2. Laboratory Safety/Precautions Science is a hands-on laboratory class. You will be doing many laboratory activitiesthat require the use of different apparatus and hazardous chemicals. Safety in the scienceclassroom is the number one priority for students and teachers. To ensure a safe scienceclassroom, a list of rules has been developed. These rules must be followed at all times.The science laboratory is a safe place to work in if you are careful. What you will do Activity 2.1 Following are some safety precautions to help you protect yourself from injury in thelaboratory while doing the experiment. Read and understand them to insure your safetybefore, during, and after doing an experiment.A. Inside the Laboratory - 13 -

1. Do not eat food, drink beverages, or chew gum in the laboratory. Do not use laboratory glassware as containers for food or beverages.2. Safety goggles and aprons must be worn whenever you work in the lab. Gloves should be worn whenever you use chemicals that cause skin irritations or when you need to handle hot equipment.3. Observe good housekeeping practices. Work areas should be kept clean and tidy at all times.4. Know the locations and operating procedures of all safety equipment including the first aid kit, eyewash station, safety shower, spill kit, fire extinguisher, and fire blanket. Know where the fire alarm and the exits are located.5. Be alert and proceed with caution at all times in the laboratory. Notify the instructor immediately of any unsafe conditions you observe.6. Dispose all chemical waste properly. Never mix chemicals in sink drains. Sinks are to be used only for water and those solutions designated by the instructor. Solid chemicals, metals, matches, filter paper, and all other insoluble materials are to be disposed of in the proper waste containers.7. Labels and equipment instructions must be read carefully before use.8. Keep hands away from your face, eyes, mouth, and body while using chemicals. Wash your hands with soap and water after performing all experiments. Clean (with detergent powder), rinse, and dry all work surfaces and equipment at the end of the experiment.9. If you spill acid or any other corrosive chemical on you skin or clothes, immediately wash the area with large amounts of water (remember that small amounts of water may be worse than no water at all). After this, get the teacher’s attention. The spill kit will be used for spills on floor or counter-top.10. After doing an experiment check if: a) the main gas outlet valve is shut off b) the water is turned off c) the desk top, floor area, and sink are clean d) all equipment are cool, clean, and arranged properly.B. Clothing1. Wear goggles or eye protector if necessary.2. Dress properly during a laboratory activity. Long hair, dangling jewelry, and loose or baggy clothing are a hazard in the laboratory. Wear an apron. Shoes must completely cover the foot. - 14 -

C. Accidents and Injuries1. Report any accident or any untoward incident to your teacher.2. If a chemical should splash in your eye(s), immediately flush with running water from the eyewash station for at least 20 minutes. Notify your teacher immediately.D. Handling Chemicals1. All chemicals in the laboratory are to be considered dangerous. Do not touch, taste, or smell any chemical unless specifically instructed to do so. The proper technique for smelling chemical fumes is to gently fan the air above the chemical toward your face.2. Check the label on reagent bottles twice before removing any of the contents. Take only as much chemical as you need. Smaller amounts often work better than larger amounts. Label all containers and massing papers holding dry chemicals.3. Never return unused chemicals to their original containers.4. Acids must be handled with extreme care. ALWAYS ADD ACID SLOWLY TO WATER, with slow stirring and swirling, being careful of the heat produced, particularly with sulfuric acid.5. Handle flammable hazardous liquids over a pan to contain spills. Never dispense flammable liquids anywhere near an open flame or source of heat.E. Handling Glassware and Equipment1. Inserting and removing glass tubing from rubber stoppers can be dangerous. Always lubricate glassware (tubing, thistle tubes, thermometers, etc.) before attempting to insert it in a stopper. Always protect your hands with towels or cotton gloves when inserting glass tubing into, or removing it from, a rubber stopper. If a piece of glassware becomes \"frozen\" in a stopper, take it to your instructor for removal.2. When removing an electrical plug from its socket, grasp the plug, not the electrical cord. Hands must be completely dry before touching an electrical switch, plug, or outlet.3. Examine glassware before each use. Never use chipped or cracked glassware. Never use dirty glassware. Do not immerse hot glassware in cold water; it may shatter.4. Report damaged electrical equipment immediately. Look for things such as frayed cords, exposed wires, and loose connections. Do not use damaged electrical equipment.F. Heating Substances1. SHOULD THE FLAME OF THE BUNSEN BURNER GO OUT, IMMEDIATELY TURN - 15 -

OFF THE GAS AT THE GAS OUTLET VALVE. If you wish to turn off the burner, do so by turning off the gas at the gas outlet valve first, then close the needle valve and barrel. Never reach over an exposed flame. Light gas burners only as instructed by the teacher.2. Never leave a lit burner unattended. Never leave anything that is being heated or is visibly reacting unattended. Always turn the burner or hot plate off when not in use.3. Do not point the open end of a test tube being heated at yourself or anyone else.4. Heated metals, glass, and ceramics remain very hot for a long time. They should be set aside to cool and then picked up with caution. Use crucible tongs or heat-protective gloves if necessary. Determine if an object is hot by bringing the back of your hand close to it prior to grasping it. What you will do Activity 2.2 Look at the picture below. From the safety precautions listed above, what are someof the rules that are followed strictly and what are those that are violated in the picture.Write your answers on the space provided below: (List at least 5 each) - 16 -

Rules that are strictly followed: ____________________________________________________________________ ____________________________________________________________________ ____________________________________________________________________ ____________________________________________________________________ ____________________________________________________________________ Rules that are violated: ____________________________________________________________________ ____________________________________________________________________ ____________________________________________________________________ ____________________________________________________________________ ____________________________________________________________________ What you will do Self-Test 2.1Write YES if the statement is a good safety rule in the laboratory and NO, if it is not.1. Avoid using protective equipment such as gloves, goggles and aprons. ________2. Use heat resistant containers for hot materials. ________3. When heating liquid substances in a test tube, hold it in an upright position, away from your body and everyone else in the laboratory room. ________4. TASTE substances in the laboratory room even if you are NOT told to do so. ________5. Play with open flames inside the laboratory. ________6. Report any untoward incident to the teacher, no matter how small. ________7. When removing an electrical plug from its socket, grasp the electrical cord. ________8. In diluting an acid ALWAYS POUR WATER SLOWLY TO ACID. ________9. Never bring your food and drinks in the laboratory. ________10. When inside the laboratory, NEVER start an experiment unless you are told to do so. ________ Key to answers on page 27.Lesson 3. Laboratory Safety Symbols The idea of using symbols is to transmit information regarding your safety inside thelaboratory clearly and easily. The safety symbols that will be presented in this module arethe most familiar ones. These symbols are accompanied by explanations. - 17 -

SAFETY SYMBOLS HAZARD EXAMPLES PRECAUTION DISPOSAL Special disposal Chemicals, Dispose ofBIOLOGICAL considerations broken glass, wastes as required living organisms directed by your EXTREME such as bacterial teacher HEAT cultures, protests, etc. SHARP OBJECT Organisms or Bacteria, fungus, Avoid skin organic materials blood, raw contact with FUME that can harm organs, plant organisms or humans material material. WearELECTRICAL dust mask or Objects that can Boiling liquids, gloves. Wash burn skin by hot plates, liquid hands thoroughly being too cold or nitrogen, dry ice, Use proper too hot all burners protection when handling. Use of tools or Razor blade, Remove glassware that scalpel, nails, flammables from can easily push pins, etc. the area around puncture or slice open flames or skin Ammonia, spark sources heating sulfur, Potential danger moth balls, nail Practice common to olfactory tract polish remover, sense behavior from fumes acetone, any and follow volatile guidelines for Possible danger substances use of the tool from electrical shock or burn Improper Make sure there grounding, liquid is good spills, short ventilation and circuits never smell fumes directly Double-check setup with instructor. Check condition of wires and apparatus - 18 -

SAFETY SYMBOLS HAZARD EXAMPLES PRECAUTION CORROSIVE Substances (acids and Acid such as Wear goggles TOXIC bases) that can vinegar, and an apronRADIOACTIVE react with and hydrochloric FLAMMABLE destroy tissue acid, hydrogen Follow your and other peroxide, sodium teacher HYGIENE materials hydroxide, soap instructions. Poisonous Always wash substances that Mercury, many hands thoroughly can be acquired metal after use through skin compounds, absorption, iodine, poinsettia Be careful in inhalation, or leaves handling. Notify ingestion your teacher of Uranium, spills or excess Radioactive thorium, substances substances such plutonium and as uranium and other elements Avoid heat and plutonium that emit flame sources. radiation Be aware of Combustible locations of fire materials that Alcohol, safety equipment may ignite if powders, exposed to an kerosene, Always wash open flame or potassium your hands after spark permanganate completing an experiment. What you will do Self-Test 3.1Write the meaning of the following symbols.1. __________________ 2. __________________ - 19 -