Class 10 Sample Science Module

10C02–Acids,BasesandSalts 1 FifthEdition 10C02.Acids,BasesandSalts TABLEOFCONTENTS 10C02.Acids,BasesandSalts 1 10C02.1PhysicalPropertiesofAcidsandBases 2 10C02.2ChemicalPropertiesofAcidsandBases 5 10C02.3AcidicandBasicNature 8 10C02.4pHScaleandUniversalIndicator 10 10C02.5SaltsandtheirProperties 13 10C02.6CommonSaltDerivatives 15 AdvancedPracticeProblems 17

10C02–Acids,BasesandSalts 2 AnswerKey 19 10C02.1PhysicalPropertiesofAcidsandBases CONCEPTSCOVERED 1. Physicalcharacteristicsofacidsandbases 2. Indicatorsandtheirtypes–naturalandsynthetic,olfactoryindicators 3. Reactionofacidswithmetals 4. Reactionofbaseswithmetals INCLASSEXERCISE Q1. Whichofthefollowingstatementsshowsthepropertyofanacid? A) Itturnsbluelitmustored B) Itissourintaste C) Ithasnoeffectonredlitmus D) Alloftheabove Q2. Whichgasisusuallyliberatedwhenanacidreactswithametal?Illustratewithanexample.Howwillyoutest forthepresenceofthisgas? Q3. Whatareindicators?Namefouracid-baseindicatorsandmentiontheircolourchange. Q4. Whatareolfactoryindicators?Giveanexample. Q5. Thefollowingfoursubstancesarepouredinthefourdifferenttesttubes,andequalpiecesofzincgranulesare droppedineachtesttube.Whichsubstance(s)willleadtoaliberationofH2gas? A) CH3COOH B) HCl C) NaOH D) H2O Q6. Foursetupsasgivenbelowarearrangedtoidentifythegasevolvedwhendilutehydrochloricacidwasadded tozincgranules.Eachofthesetupsisshownwithaburningmatchoverthetesttube.Whichisthemost appropriatesetup? 10C02.1

10C02–Acids,BasesandSalts 3 A) I B) II C) III D) IV Q7. Whileeatingfood,youspillsomecurryonyourwhiteshirt,whichleavesayellowstain.Youscrubitwithsoap. I. Whathappenstoitsyellowcolouronscrubbingwithsoap? II. Whydoesthishappen? III.Whathappenstothisstainwhentheshirtiswashedwithplentyofwater? Q8. Whyshouldcurdandsoursubstancesnotbekeptinbrassandcoppervessels? Q9. Youhavebeenprovidedwiththreetesttubes.Oneofthem containsdistilledwaterandtheothertwocontain anacidicsolutionandabasicsolution,respectively.Ifyouaregivenonlyredlitmuspaper,howwillyouidentify thecontentsofeachtesttube? HOMEWORK Q1. Namesomecommonbases,withtheirchemicalnameandformula. Q2. Fillintheblanks I. Thecolouroflitmussolution,whenitisneitheracidic,norbasic,is__________ II. Turmericsolution,inpresenceofsoapwillbecome__________incolour. III.Olfactoryindicatorsindicatethepresenceofacidsorbasesbyachangein__________ Q3. Givetwophysicalcharacteristicseachofacidsandbases. Q4. Defineindicators.Nametwonaturalindicatorsobtainedfromplants. Q5. State2waysinwhichyoucantestthepresenceofanacidinanysubstance. Q6. Writethereactionthatwilloccurwhenzincgranulesareaddedtopotassiumhydroxidesolution. 10C02.1

10C02–Acids,BasesandSalts 4 Q7. Mentionthefinalcolourofthesolutionineachofthefollowingcases: I. Turmeric+vinegar II. BlueLitmussolution+lemonjuice III.RedLitmussolution+soapsolution IV.Methylorange+HCl Q8. WhichoneofthefollowingwouldyouneedtoidentifythegasthatevolveswhenyouheatNaOHsolutionwith zincmetal? A) Redlitmussolution B) Bluelitmussolution C) Aburningsplinter/matchstick D) Limewater Q9. Aknife,afterbeingusedtocutafruit,wasimmediatelydippedintowatercontainingdropsofbluelitmus solution.Ifthecolourofthesolutionchangestored,whatinferencecanbedrawnaboutthenatureofthefruit andwhy? Q10.WhathappensifyouputonionjuiceindiluteNaOH?WhathappensifyouputitindiluteHClinstead?Canwe useonionasanindicator? Q11.Youaresenttobuyvinegar(aceticacid)from thegrocerystore.Youseetwooptions,oneisaglassjarof vinegar,andtheotherisanaluminiumcanofvinegar. I. Whichonewouldyoubuy? II. Givereasonsforyourchoice,withachemicalreactiontosupportyouranswer. ADVANCEDQUESTIONS Q1. Whyarezincgranulesusedinsteadofapieceofzincmetal,whenzincisreactedwithdil.HCl? Q2. TwotestswerecarriedoutonacolorlessliquidX.Xturnedanhydrouscopper(II)sulphatefromwhitetoblue. Xreactedwithcalcium,givinghydrogen.WhatcouldXbe? I. Dilutehydrochloricacid II. Ethanol III.Water 10C02.1

10C02–Acids,BasesandSalts 5 D) IandIII A) Ionly B) IIonly C) I,IIandIII Q3. Metalsreactwithacidstogivesaltandhydrogengas.Someofthesemetalsalsoreactwithbasestogivesaltand hydrogen.Thesespecialmetals,thatreactwithbothacidsandbasesaresaidtobeamphotericinnature.Afew examplesofamphotericmetalsarezinc,aluminium,tinetc.Writethebalancedequationsforreactionsof aluminiumwithanacidandabase. Q4. Thereactivityseriesofmetalsalsohasaspecialmember,hydrogen.Eventhoughhydrogenisnotametal,its tendencytoform bondswithnon-metalsishigherthanafew metals.Therevisedreactivityseries,after inclusionofhydrogen,thusbecomes:K,Na,Ca,Mg,Al,Zn,Fe,Pb,H,Cu,Hg,Ag,Au,Pt.Basedonthisinformation, answerthequestionthatfollows: Youleaveapieceofgoldinacidforafewhours,butnoobservablereactionhastakenplace.Why? 10C02.2

10C02–Acids,BasesandSalts 6 10C02.2ChemicalPropertiesofAcidsandBases CONCEPTSCOVERED 1. Reactionofacidswithmetalscarbonatesandmetalbicarbonates 2. Reactionofacidswithbases 3. Basicoxidesandtheirreactionwithacids 4. Acidicoxidesandtheirreactionwithbases INCLASSEXERCISE Q1. Distinguishbetweenmetalsandnon-metalswithrespecttothenatureoftheiroxides. Q2. Writebalancedchemicalequationsforthereactionofdil.HClwith I. Na2CO3 II. NaOH Q3. 10mLofasolutionofNaOHisfoundtobecompletelyneutalisedby8mLofagivensolutionofHCl.Ifwetake 20mLofthesamesolutionofNaOH,whatwillbetheamountofthesameHClsolutionrequiredtoneutraliseit? Q4. Astudentperformedanexperimentusingdifferentchemicalsunderdifferentconditionsasshownhere. Inwhichsetup,nogasisevolved? A) I B) II C) III D) IV Q5. Anaqueoussolutionturnsredlitmussolutionblue.Excessadditionofwhichsolutionwouldreversethechange? Q6. MetalcompoundAreactswithdilutehydrochloricacidtoproduceeffervescence.Thegasevolvedextinguishes aburningcandle.Writeabalancedchemicalequationforthereaction,ifoneofthecompoundsformedis calciumchloride. 10C02.2

10C02–Acids,BasesandSalts 7 Q7. Whathappenswhennitricacidisaddedtoeggshells? Q8. Youmighthaveseenlemonortamarindjuicebeingusedtocleantarnishedsurfaceofcoppervessels.Explain whythesesoursubstancesareeffectiveincleaningthevessels? HOMEWORK Q1. Whatisaneutralizationreaction?Givesomeexamples. Q2. Whatisthenatureofnon-metallicoxides?Explainyouranswerwithanexample. Q3. Completeandbalancethefollowingequations: I. H2CO3 + NaOH→ II. CH3COOH+ NH4OH→ III.HNO3 + KOH→ IV.H2SO4 + NaOH→ Whataretheabovereactionscalled?Namethesaltformedineachcase. Q4. Listimportantphysicalandchemicalcharacteristicsofacids. Q5. Listimportantphysicalandchemicalcharacteristicsofbases. Q6. Howdoacidsreactwithmetalcarbonates?Writethegeneralequationandalsogiveanexample. Q7. Whatwillhappen ifyou add diluteHClto copperoxide(CuO)?Supportyourobservationswith the correspondingbalancedchemicalequation. Q8. Answerthefollowingquestionsaboutacidicoxides I. Whichoxidesareknownasacidicoxides? II. Giveexamplesofsomeacidicoxides. III.Howdoacidicoxidesreactwithbases? IV.Writethebalancedequationofthereactionofany2acidicoxideswithNaOH Q9. Matchthecolumns P. Zn A. HClwillreactwith B. NaOHwillreactwith Q. Na2CO3 R. NaHCO3 S. KOH T. H2SO4 AvantiLearningCentres 10C02.2

10C02–Acids,BasesandSalts 8 U. Na V. SO3 W.Na2O Q10.Inabeaker,NaOHsolutionandHClsolutionaremixed,andafew dropsofphenolphthaleinareadded.Itis observedthatthephenolphthaleinturnspink.Whichofthetwosolutions(HClorNaOH)wouldyouaddmore of,tomakethesolutioncolourless? Q11.AchemicalXreactswithHCltogiveapotassium salt,alongwithwater,andagasthatturnslimewatermilky. CompoundXdoesnothavehydrogenasaconstituent.WhatisX?Writethebalancedchemicalequationforthe reactionofXwithHCl. ADVANCEDQUESTIONS Q1. Indicatorsarethemselvesweakacidsandbasesthatreactwiththesolutiontogivesaltsofdifferentcolours. Basedonthisinformation,andtheknowledgethatphenolphthaleiniscolourlessinneutralandacidicmedium, butpinkinbasicmedium,predictwhetherphenolphthaleinisaweakacidoraweakbase. Q2. Wealreadyknow thatmetalsreactwithdiluteHCltogiveH2.MetalsalsoreactwithdiluteH2SO4togiveH2, whichcanberepresentedas: Fe+ H2SO4→FeSO4 + H2↑ WealsoknowthatacidsliberateCO2onreactionwithmetalcarbonatesandbicarbonates. However,acidsalsoreactwithvariousothersubstancesinthefollowingmanner: I. Withsulphitesandbisulphites: CaSO3 + 2HCl→CaCl2 + H2O+ SO2↑ Thegasreleased(SO2,sulphurdioxide)turnsacidifiedpotassium dichromatesolutionfrom orangeto green. II. Withsulphides: FeS+ 2HCl→FeCl2 + H2S↑ Thegasreleased(H2S,hydrogensulphide)canbedetectedbyitssmell.Itsmellslikerotteneggs. III.Withchlorides: MetalchloridesusuallyreactwithconcentratedacidstoliberateHClgas. NaCl+ H2SO4→above200oC Na2SO4+HCl↑ Hydrogenchloridegashasnocolourbutitfumesinmoistair(itlooksmisty).Ithasapungentsmell andturnsmoistlitmuspaperfrombluetored. Basedontheaboveinformation,completethefollowingreactionsandwritehow youwilltestthetypeof gasevolvedinthefollowingcases. 10C02.2

10C02–Acids,BasesandSalts 9 i) Mg+ HCl→ ii) CuO+ H2SO4→ iii) NaHSO3 + HCl→ iv) CaCO3 + HCl→ v) ZnS+ HCl→ vi) Ca(HCO3)2 + HCl→ 10C02.2

10C02–Acids,BasesandSalts 10 10C02.3AcidicandBasicNature CONCEPTSCOVERED 1. Acidicnatureofacids 2. Basicnatureofbases 3. Acidsandbasesaselectrolytes 4. Behaviourofacidsandbasesinabsenceofaqueousmedium 5. Dilutionofacidsandbases INCLASSEXERCISE Q1. Whichbasesarecalledalkalis?Giveanexampleofanalkali. Q2. Identifythenumberofremovablehydrogenions(H+)inthefollowingacids: I. HCl II. CH3COOH III.H2SO4 Q3. Howistheconcentrationofhydroniumions(H3O+)affectedwhenasolutionofanacidisdiluted? Q4. Howwillthefollowingsubstancesdissociatetoproduceionsintheirsolutions? I. Nitricacid II. Sulphuricacid III.Potassiumhydroxide Q5. Whatwillbetheactionofthefollowingsubstancesonlitmuspaper? I. DryHClgas II. MoistenedNH3gas Q6. Inanattempttodemonstrateelectricalconductivitythroughanelectrolyte,thefollowingapparatuswassetup. 10C02.3

10C02–Acids,BasesandSalts 11 Willthebulbglowinthiscase?Givereasonsforyouranswer. Q7. Dryammoniahasnoactiononlitmuspaperbutasolutionofammoniainwaterturnsredlitmuspaperblue. Whyisitso? Q8. Compoundslikealcoholandglucosewhichcontainhydrogenarenotcategorizedasacids.Why?Describean activitytojustifyyouranswer. Q9. Whyisitrecommendedthatweaddconc.acidtowater,insteadofaddingwatertoconc.acid? HOMEWORK Q1. Whatdoallacidshaveincommon? Q2. Fillintheblanks I. Hydrogenion,aftercombiningwithwatermolecules,formsthe_________ion. II. Basesgenerate_________ioninwater. III.Baseswhicharesolubleinwaterarecalled_________. IV.Theprocessofdissolvingacidsorbasesinwaterishighly__________. Q3. Distinguishbetweenbaseandalkali. Q4. Whatdoyoumeanbydilutionofanacidorbase?Whyisitdone? Q5. How willthefollowingsubstancesdissociatetoproduceionsintheirsolutions?Show theirdissociation reactions. I. Hydrochloricacid II. Sodiumhydroxide III.Magnesiumhydroxide Q6. WhydoeselectricityflowthroughaqueoussolutionsofHClandNaOH,butnotthroughglucose? Q7. Whydoacidsnotshowacidicbehaviourinabsenceofwater? 10C02.3

10C02–Acids,BasesandSalts 12 Q8. Inwhichofthefollowingcaseswillyouobserveachangeincolour,whendryammoniagasispassedover: A) Drybluelitmuspaper B) Moistbluelitmuspaper C) Dryredlitmuspaper D) Moistredlitmuspaper Q9. HowisdryHClproduced?Whatdoyouobservewhenyoupassitoverbluelitmuspaper? ADVANCEDQUESTIONS Q1. Thehumanbodyismadeof70% waterandothersubstanceslikesugars,proteinsetc,whichdonotconduct electricityinsolution.Whydowefeelmildshocksorcurrentssometimes? Q2. Sofar,wehaveseenthefollowingdefinitionsofacidsandbases:anacidisanysubstancethationizeswhenit dissolvesinwatertogivetheH+ ion,andabaseisanysubstancethatgivestheOH-ionwhenitdissolvesin water.ThisisreferredtoastheArrheniustheoryofacidsandbases.G.N.Lewisalsogaveatheory,accordingto whichaLewisacidisanysubstancethatcanacceptapairofelectrons.ALewisbaseisanysubstancethatcan donateapairofelectrons.SpottheLewisacidandbaseinthefollowingreactions: I. H+ + Cl-→HCl II. 2Na+ + SO4-2→Na2SO4 Q3. WeknowthatacidsdissociateinsolutiontogiveH+ionsandbasesdissociatetogiveOH-ions. Thenumberofionizablehydrogen(H+)ionspresentinonemoleculeofanacidiscalleditsbasicity.For example, HCl(aq)→H+ + Cl-:Basicity= 1 H2SO4(aq)→2H+ + SO42-:Basicity = 2 Also,thenumberofionizablehydroxideions(OH-)presentinonemoleculeofabaseiscalleditsacidity. Forexample, NaOH(aq)→Na+ + OH-:Acidity= 1 Ca(OH)2(aq)→Ca2+ + 2OH-:Acidity = 2 Basedonthisinformation,writedowntheacidityorbasicityoffollowingcompounds: I. Nitricacid II. Sodiumhydroxide III.Sulphuricacid IV.Aceticacid V. Calciumhydroxide VI.Phosphoricacid(H3PO4) 10C02.3

10C02–Acids,BasesandSalts 13 10C02.4

10C02–Acids,BasesandSalts 14 10C02.4pHScaleandUniversalIndicator CONCEPTSCOVERED 1. Universalindicator 2. pHscale 3. Weakandstrongacidsandbases 4. ImportanceofpHinourdailylives INCLASSEXERCISE Q1. Nametheacidpresentinthefollowingnaturallyoccurringitems: I. Lemonjuice II. Vinegar III.Tamarind IV.Tomato V. Orange VI.Curd VII.Ants Q2. WhatispH? Q3. Completethetableaboutcommonindicatorsandtheircolourinacidsandalkalis. Indicator Colourinacid Colourinalkali Litmus Red __________ Methylorange __________ Yellow __________ Colourless Pink __________ Red,pink,orange Turquoise,blue,violet Q4. FivesolutionsA,B,C,DandEwhentestedwithuniversalindicatorshowedpHas4,1,11,7and9,respectively. Whichsolutionis(I)neutral(II)stronglyalkaline(III)stronglyacidic(IV)weaklyacidicand(V)weakly alkaline? ArrangethesolutionsinincreasingorderofH+ionconcentration. Q5. AdropofaliquidsamplewasputonthepHpaper.ItwasobservedthatthecolourofthepHpaperturnedblue. Theliquidsampleis A) Lemonjuice B) Sodiumbicarbonatesolution C) Distilledwater D) Hydrochloricacid Q6. Whenadropoforangejuiceisaddedtopurewater,howwillthepHvaluevaryforwater?Ifadropoflemon 10C02.4

10C02–Acids,BasesandSalts 15 juiceisalsoadded,willtherebeanymorechangeinpHvalue? Q7. YouhavetwosolutionsAandB.ThepHofsolutionAis6andpHofsolutionBis8. I. Whichsolutionisacidicandwhichisbasic? II. WhichsolutionhasmoreH+ionconcentration? Q8. WhyisHClastrongeracidthanaceticacid? Q9. FreshmilkhasapHof6.HowdoyouthinkthepHwillchangeasitturnsintocurd?Explain. Q10.AnswerthefollowingquestionsonpHchangeinsidethemouth: I. WhendoesthepHinsidemouthdecrease? II. Whatistheill-effectoftheacidicmedium? III.Howcanthisbeprevented? Q11.Whichtypeofmedicineisusedfortreatingindigestion? HOMEWORK Q1. TwosolutionsXandYwerefoundtohavepHvalueof4and10respectively.Theinferencethatcanbedrawnis A) XisbaseandYisanacid B) BothXandYareacidicsolutions C) XisanacidandYisabase D) BothXandYarebases. Q2. AfewdropsofliquidXwereaddedtodistilledwater.ItwasobservedthatthepHofthewaterdecreased.What couldtheliquidsampleXbe? Q3. ArrangethefollowinginanincreasingorderoftheirpHvalues NaOHsolution,blood,lemonjuice. Q4. WhatispHscale?Howisitcalibrated? Q5. PlacethesesubstancesatthecorrectpHvalueinthetable. Purewater Batteryacid Toothpaste Ovencleaner Applejuice pH Substance 1 4 7 10C02.4

10C02–Acids,BasesandSalts 16 9 14 Q6. Listtwofunctionsperformedbydilutehydrochloricacidinourstomach. Q7. Whatistheuniversalindicator?Inwhatwayistheuniversalindicatormoreefficientthanotherindicators? Q8. StatethepHofdistilledwaterandrainwater.Justifyyouranswerwithproperreasoning. Q9. Whatareantacids? Q10.Answerthefollowingquestionsaboutthetoothenamel. I. Whatistoothenamelchemically? II. Statetheconditionwhentheenamelstartscorroding. III.Whathappenswhenfoodparticlesthatareleftinthemouthaftereating,degrade? IV.Whydodoctorssuggestuseoftoothpowder/toothpastetopreventtoothdecay? Q11.Whatisacidrain?Howdoesitaffectouraquaticlife? Q12.Amilkmanaddsaverysmallamountofbakingsodatofreshmilk. I. WhydoesheshiftthepHofthefreshmilkfrom6toslightlyalkaline? II. Whatdoyouexpecttoobservewhenthismilkcomestoboil? III.Whydoesthismilktakealongtimetosetasacurd? Q13.Farmersareusingalargenumberofpesticidesandfertilisersintheirfieldstoincreasecropproductionandto enhancetheirprofits.Butbydoingso,theyarecausingdamagetothesoilaswellastotheenvironment. Doyouagreewiththisstatement?Whyshouldweavoideatingfruitsandvegetableswithoutwashingthem properly? Q14.Writeashortnoteontheroleofacidsinselfdefenceoforganisms. 10C02.4

10C02–Acids,BasesandSalts 17 ADVANCEDQUESTIONS Q1. Howdoesastrongaciddifferfromaconcentratedacid? Q2. ThepHofahydrochloricacidsolutionis3.Doesthismeanthatithasonlyhydronium ions?Givereasonsfor youranswer. Q3. Salivaryamylase,anenzymepresentinsalivahelpsinthedigestionofstarchintoglucoseinthepHrange 6.2-7.6.Supposewetake5mLof1% starchsolutionintwotesttubesAandB.Thenwepour2mLofsalivain eachtesttube,andintesttubeA,weput2-3dropsofHCl.Whatwillhappenifwethenadd2-3dropsofiodine ineachtesttube?Notethatiodineturnsblueinpresenceofstarch. 10C02.4

10C02–Acids,BasesandSalts 18 10C02.5SaltsandtheirProperties CONCEPTSCOVERED 1. Familiesofsalts 2. pHofsalts–acidic,basicandneutralsaltsolutions 3. Waterofcrystallisationofsalts 4. PlasterofParisanditsuses 5. Commonsalt INCLASSEXERCISE Q1. Classifythefollowingsaltsasacidic,basicandneutral I. Sodiumchloride II. Ammoniumchloride III.Sodiumacetate Q2. Writethechemicalnamesoftwosaltsbelongingtosodiumfamily. Q3. AstudenthasfoursamplesA,B,C,Dcontainingdil.HCl,NaClsolution,dil.NaOHanddistilledwaterrespectively. WhichtwosampleswouldshowequalvalueofpH? Q4. Whatismeantby‘waterofcrystallisation’ofasubstance?Nameanysaltwhichdoesnotcontainwaterof crystallization. Q5. Howiscommonsaltpreparedfromseawater? Q6. Howaresaltsformed?WhatdeterminestheirpHvalueinaqueoussolution? Q7. AnswerthefollowingquestionsaboutPlasterofParis: I. WhatisthechemicalformulaofPlasterofParis? II. WhereisPlasterofParisused? III.WritethechemicalequationofconversionofPlasterofParistogypsum Q8. Describeanactivitytoshowthatbluecoppersulphatecrystalscontainwaterofcrystallization. HOMEWORK Q1. Writethechemicalnamesoftwosaltsbelongingto: 10C02.5

10C02–Acids,BasesandSalts 19 I. chloridefamily II. calciumfamily Q2. Outoftwosaltsbakingsodaandwashingsoda,whichsaltdoesnotcontainwaterofcrystallization? Q3. Fillintheblanks: I. Thesaltthatweuseinfoodismadebythebase:_____________andtheacid:_________. II. Crystalsofsolidsaltare______incolourduetoimpuritiesandarereferredtoas______salt. Q4. Asaltisdissolvedinwater.ThepHofthissaltsolutionwasfoundtobe7bymeasuringthepHwithauniversal indicatorpaper.Thesaltismostlikelytobe A) Na2CO3 B) KCl C) NH4Cl D) CH3COONa Q5. Amongthefollowingsalts,whichsaltsareacidic,basicorneutral? Sodiumchloride Potassiumnitrate Aluminiumchloride Zincsulphate Sodiumacetate Sodiumcarbonate Coppersulphate Sodiumsulphate Ammoniumsulphate Q6. Whatisthechemicalformulaofhydratedcoppersulphate?Writethecoloursofhydratedandanhydrous coppersulphatecrystals. Q7. Howwasrocksaltformed?Howisitobtainedatalargescale? Q8. HowdoweconvertgypsumtoPlasterofParis?WhydoesPlasterofParishaveonlyhalfamoleculeofwateras waterofcrystallization? Q9. WhathappenstothecrystalsofNa2CO3inpresenceofmoisture? Q10.Howiscommonsaltobtained? Q11.Whichofthefollowingistrueaboutasolutionofammoniumchloride? A) ItspHwillbemorethan7 B) ItwillturnpHpaperblue 10C02.5

10C02–Acids,BasesandSalts 20 C) Itwillturnbluelitmussolutionred D) ItbelongstothesamefamilyofsaltsasPlasterofParis Q12.WhyshouldPlasterofParisbestoredinamoisture-proofcontainer? ADVANCEDQUESTIONS Q1. Therearemanykindsofsalts.Someofthetypesarelistedhere. Normalsalts:Saltsformedbycompletereplacementoftheionisablehydrogenatomsofanacidbyametallicor anammoniumion.Eg.NaCl Acidsalts:Saltsformedbythepartialreplacementoftheionisablehydrogenatomsofanacidbyametaloran ammoniumion.Eg.NaHSO4 Basicsalts:Saltsformedbythepartialreplacementofthehydroxylgroupofabasebyanacid.Eg.Mg(OH)Cl Doublesalts:Saltsformedbyunionoftwosalts,whentheycrystallisetogether.Eg.CaCO3.MgCO3 Mixedsalts:Saltsthatthataremadebymorethanoneacidorbase.Eg.NaKCO3 Basedontheaboveinformation,classifythefollowingsaltsasnormal,acid,basic,doubleormixed. I. NaKSO4 II. Cu(OH)Cl III.Na2SO4 V. Cu(OH)NO3 VI.NaHSO3 ( )IV.FeSO4.NH4 2SO4.6H2O VIII.Na2HPO4 ( )IX.K2SO4.Al2 SO4 3.24H2O VII.Pb(OH)Cl Q2. Hydrolysisofsalts: Thephenomenonduetowhichasaltformedbyaweakacidandastrongbase,orbyastrongacidanda weakbase,reactswithwatertogiveanacidicoranalkalinesolution,isknownashydrolysis. Forexample: Na2CO3 + 2H2O→H2CO3 + 2NaOH Theabovereactionwillgiveanalkalinesolution. Showthehydrolysisofthefollowingsaltsbyabalancedequation,andmentionifwhetherthesolutionwill beacidicorbasic: I. FeCl3 II. CH3COOK 10C02.5

10C02–Acids,BasesandSalts 21 10C02.6CommonSaltDerivatives CONCEPTSCOVERED 1. Chlor-alkaliprocess 2. UsesofNaOH 3. Properties,usesandprocessesinvolvedforobtaining: I. Bleachingpowder II. Bakingsoda III.Washingsoda INCLASSEXERCISE Q1. Answerthefollowing: I. Namethecompoundwhichisobtainedfrom bakingsodaandisusedtoremovepermanenthardnessof water. II. Writeitschemicalformula. III.Whathappenswhenitisrecrystallizedfromitsaqueoussolution? Q2. Acalciumcompoundwhichisayellowishwhitepowerisusedasadisinfectantandalsointextileindustry. I. Namethecompound. II. StatetheequationofpreparationofthiscompoundfromCa(OH)2 Q3. Whenelectricityispassedthroughacommonsaltsolution,sodiumhydroxideisproducedalongwiththe liberationoftwogasesXandY.Xburnswithapopsound,whereasYisusedfordisinfectingdrinkingwater. I. IdentifyXandY. II. Givethechemicalequationforthereactionstatedabove. III.StatethereactionofYwithdryslakedlime. Q4. AcompoundXofsodium iscommonlyusedinkitchenformakingcrispypakoras.Itisalsousedforcuring acidityinthestomach.IdentifyX.Whatisitschemicalformula?Statethereactionwhichtakesplacewhenitis heatedduringcooking. Q5. Whyistartaricacidaddedintobakingsodatogetbakingpowder? Q6. AdrypelletofacommonbaseBwhenkeptinopenabsorbsmoistureandturnssticky.Thecompoundisalsoa productofchlor-alkaliprocess. 10C02.6

10C02–Acids,BasesandSalts 22 I. IdentifyB. II. WhattypeofreactionoccurswhenBistreatedwithanacidicoxide? III.Writeabalancedchemicalequationforonesuchoxide. HOMEWORK Q1. Howissodiumhydroxideproduced?Writethebalancedchemicalequation.Whyisthisprocesscalledaschlor- alkaliprocess?Inthisprocess,nametheproductsgivenoffat I. anode II. cathode Q2. Whichsodiumsaltisusedtomakeborax? Q3. Statethebalancedequationofrecrystallisationofsodiumcarbonate. Q4. Statethebalancedequationforthereactionthattakesplaceduringpreparationofbakingsodafrom common salt. Q5. Writeoneuseeachof I. Hydrogengas II. Chlorinegas III.NaOH IV.Hydrochloricacid V. Bleach Q6. Describethereactionthattakesplaceinsoda-acidfireextinguishers,whenNaHCO3reactswithsulphuricacid. Q7. Whenasodium compoundXwhichisalsousedinsoda-acidfireextinguisherisheated,givesasodium compoundYalongwithwaterandcarbondioxide.YoncrystallizationformscompoundZ. I. IdentifyX,YandZ II. WritetwousesofthecompoundZ. Q8. SaltAiscommonlyusedinbakeryproducts.Onheating,AgetsconvertedintoanothersaltBwhichitselfis usedforremovalofhardnessofwaterandagasCisevolved.ThegasCwhenpassedthroughlimewater,turns itmilky.IdentifyA,BandC.Writebalancedchemicalequationsforeachstep. ADVANCEDQUESTIONS Q1. In1791,theFrenchchemistNicolasLeblancpatentedaprocessforproducingsodium carbonatefrom salt, sulfuricacid,limestone,andcoal.First,seasaltwasboiledinsulfuricacidtoyieldXandhydrogenchloridegas. 10C02.6

10C02–Acids,BasesandSalts 23 Further,Xwasblendedwithcrushedlimestoneandcoal,andthemixturewasburnt,toproducesodium carbonate.IdentifyXandwritebalancedchemicalequationsforboththesuccessivereactions. Q2. Bleachingpowderalwayssmellsofchlorinebecausecarbondioxidepresentinairdecomposesitslowlyto producechlorinegas.Writethebalancedchemicalequationforthisreaction. Q3. Inthepresenceofaverysmallamountofdiluteacid,thebehaviorofbleachingpowderisaccordingtothe reactiongivenbelow: 2CaOCl2 + H2SO4→CaCl2 + CaSO4 + 2HCl+ 2[O] Whichoftheaboveproductsleadtotheoxidisingandableachingactionofbleachingpowder? A.P.P.

10C02–Acids,BasesandSalts 24 AdvancedPracticeProblems Q1. WeknowthatacidmoleculesdissociateinaqueousmediumtogiveH+ions.However,notallmoleculescan successfullydissociateatroomtemperature(298K).Interestingly,asweincreasethetemperatureofthe solution,moreandmoremoleculesstartdissociating.Asaresult,thenumberofH+ionskeepsincreasingfor thesamesolution.Basedinthisinformation,answerthefollowingquestions: I. ThepHofdil.HClis4atroomtemperature.WhatwillbetheexpectedpHofthisacidat350K? II. WillthepHofdistilledwateralwaysbe7?Givereasonsforyouranswer. Q2. SpottheLewisacidandbaseinthefollowingreactions: I. 2H+ + SO24-→H2SO4 II. Na+ + Cl-→NaCl Q3. Showthehydrolysisofthefollowingsaltsbyabalancedequation,andstatewhetherthesolutionwillbeacidic orbasic: I. CuSO4 II. CH3COONa Q4. Anexcessofdilutesulphuricacidreactswithbothaqueousbariumhydroxideandaqueousbariumchloride.In whatwayarethetworeactionssame? A) Agasisproduced B) Aninsolublesaltisproduced C) FinalpHis7 D) Waterisproduced Q5. Twosolutionsaremixedinabeakerandthemassofthebeakerandthecontentsisthenrecordedatvarious times.Thegraphshowsthefollowingresults: Whatcouldbethetwosolutions? A) Aqueouscopper(II)sulphateandaqueousammonia B) Aqueoussodiumcarbonateanddilutenitricacid C) Aqueoussodiumhydroxideandaqueouszincsulphate A.P.P.

10C02–Acids,BasesandSalts 25 D) Dilutehydrochloricacidandaqueoussodiumsulphate Q6. Completethefollowingreactionsandwritehowwillyoutestthetypeofgasevolvedinthefollowingcases? I. Fe+ HCl→ II. KHSO3 + HCl→ III.MgCO3 + HCl→ IV.CdS+ HCl→ V. Mg(HCO3)2 + HCl→ Q7. Writedowntheacidityorbasicityoffollowingcompounds: I. Sulphurousacid(H2SO3) II. Potassiumhydroxide III.Chloricacid(HClO3) IV.NitrousAcid(HNO2) V. Leadhydroxide Q8. Manybodyfluidse.g.,bloodorurinehaveadefinitepHandanydeviationintheirpHindicatesmalfunctioning ofthebody.ThecontrolofpH isalsoveryimportantinmanychemicalandbiochemicalprocesses.The solutionswhichresistchangeinpHondilutionorwiththeadditionofsmallamountsofacidoralkaliarecalled buffersolutions. Hence,theyshouldbeabletoremoveanyhydrogenionsorhydroxideionsthatareaddedtoit–otherwise thepHwillchange. Buffersolutionsareoftwotypes: I. Acidicbuffer:AnacidicbuffersolutionhasapHlessthan7.Thesearecommonlymadefrom aweakacid andoneofitssalts–oftenasodium salt.Forexample,amixtureofsodium acetateandaceticacidwillgive usanacidicbuffer. II. Alkalinebuffer:AnalkalinebuffersolutionhasapHgreaterthan7.Thesearecommonlymadefromaweak baseandoneofitssalts.Forexample,amixtureofammoniumhydroxideandammoniumchloride. Basedonthis,categorizewhetherthebuffersolutionspreparedbymixingthefollowingwillbeacidicor alkaline: i) Formicacid(HCOOH)andpotassiumformate(HCOOK) ii) Sodiumhydrogencarbonateandsodiumcarbonate iii)Citricacidandsodiumcitrate iv)Carbonicacidandsodiumhydrogencarbonate A.P.P.

10C02–Acids,BasesandSalts 26 AnswerKey 10C02.1PHYSICALPROPERTIESOFACIDSANDBASES INCLASSEXERCISE Q5. A,B,C Q1. D Q6. D HOMEWORK Q1. Somecommonbasesare: I. Causticsoda Chemicalname Chemicalformula II. Causticpotash Sodiumhydroxide NaOH III.Limewater Potassiumhydroxide KOH IV.Milkofmagnesia Calciumhydroxide Ca(OH)2 Magnesiumhydroxide Mg(OH)2. Q2. Fillintheblanks I. Turmeric+vinegar:Remainsyellow II. BlueLitmussolution+ lemonjuice:Turns I. Thecolouroflitmussolution,whenitis neitheracidic,norbasic,ispurple red III.RedLitmussolution+soapsolution:Turns II. Turmericsolution,inpresenceofsoapwill becomereddish-brownincolour. Blue IV.Methylorange+HCl:TurnsRed III.Olfactoryindicatorsindicatethepresence of acids or bases by a change in Q8. C smell/odour. Q9. Thefruitisacidicbecauseacidsolutionschange Q6. Thereactionwillleadtoformationofasalt, bluelitmussolutiontored. withliberationofhydrogengas,asshownbelow: ADVANCEDQUESTIONS 2KOH(aq)+ Zn(s)→K2ZnO2(aq) + H2(g)↑ Q2. D (Potassiumzincate) Q7. Thefinalcolourofthesolutionineachofthe followingcaseswillbe: 10C02.2CHEMICALPROPERTIESOFACIDSANDBASES INCLASSEXERCISE Q3. 16mLofthesameHClsolutionwillberequired Q2. Thebalancedchemicalreactionsare: toneutralise20mLNaOHsolution. I. Na2CO3 + 2HCl→2NaCl+ H2O+ CO2↑ Q4. D II. NaOH+ HCl→NaCl+ H2O Ans.

10C02–Acids,BasesandSalts 27 HOMEWORK Q3. Thegivenreactionscanbebalancedasshownbelow: I. H2CO3+2NaOH→ Na2CO3+ 2H2O Sodium Carbonate II. CH3COOH+NH4OH→ CH3COONH4+ H2O Ammonium Acetate III.HNO3+KOH→ KNO3 + H2O Potassium nitrate IV.H2SO4+2NaOH→ Na2SO4 + 2H2O Sodium sulphate Alltheaboveareneutralizationreactions. Thenamesofthesaltsformedare: I. Sodiumcarbonate II. Ammoniumacetate, III.Potassiumnitrate, IV.Sodiumsulphate. Q9. A:P,Q,R,S,U,W; B:P,T,V 10C02.3ACIDICANDBASICNATURE INCLASSEXERCISE Q3. Concentration ofH3O+ions perunitvolume Q1. Watersolublebasesarecalledalkalis.Eg.NaOH, decreaseswhenanacidsolutionisdiluted. KOH,etc. Q4. Dissociation ofvarious compounds in their solutions. Q2. ReplaceableH+ions. I. HCl-1 I. Nitricacid(HNO3) II. CH3COOH-1(3Hatomswillnotdissociate asH+insolution) HNO3 + H2O→H3O+ + NO-3 III.H2SO4-2 II. Sulphuricacid(H2SO4) H2SO4 + 2H2O→2H3O+ + SO42- III.Potassiumhydroxide(KOH) Ans.

10C02–Acids,BasesandSalts 28 KOH→H2OK+ + OH- HCl+ H2O→H3O+ + Cl- II. Sodiumhydroxide(NaOH) Q5. Actiononlitmuspaper: I. DryHClgashasnoeffectonlitmus. NaOHH→2ONa+ + OH- II. MoistenedNH3gasturnsredlitmusblue. III.Magnesiumhydroxide[Mg(OH)2] Q6. Thebulbwillglow. Mg(OH)2H→2OMg2+ + 2OH- HOMEWORK Q1. AllacidsgiveH+ionsinaqueousmedium,which Q8. D areresponsiblefortheiracidicproperty. ADVANCEDQUESTIONS Q2. I. Hydrogenion,aftercombiningwithwater Q3. Lewisacidsandbases: molecules,formsthehydroniumion. I. Cl-isaLewisbase II. Basesgeneratehydroxideioninwater. II. SO42-ionisaLewisbase III.Baseswhicharesolubleinwaterarecalled Q4. Acidity/Basicity: basicity–1 alkalis. I. Nitricacid acidity –1 IV.Theprocessofdissolvingacidsorbasesin II. Sodiumhydroxide basicity–2 III.Sulphuricacid basicity–1 waterishighlyexothermic. IV.Aceticacid acidity –2 V. Calciumhydroxide basicity–3 Q5. Dissociation ofvarious compounds in their VI.Phosphoricacid solutions. I. Hydrochloricacid(HCl) 10C02.4PHSCALEANDUNIVERSALINDICATOR INCLASSEXERCISE Indicator Inacid Inbase Q1. Acidsfoundinnaturallyoccurringitems: Litmus Red Blue LemonJuice Citricacid Methylorange Red/pink Yellow Vinegar Aceticacid Phenolphthalein Colourless Pink Tamarind Tartaricacid Universal Red, pink, Turquoise, indicator orange blue,violet Tomato Oxalicacid Q4. NatureofsolutionsbasedonpH: Orange Citricacid Curd Lacticacid AB C DE Ants Methanoicacid 41 11 7 9 Weakly Strongly Strongly Neutral Weakly acidic acidic basic Basic Q3. Coloursofcommonindicators (I)–D;(II)–C;(III)–B;(IV)–A;(V)–E. Ans.

10C02–Acids,BasesandSalts 29 Solutions in increasing order of H+ ion HOMEWORK concentrationare Q1. C C< E< D< A< B Q3. Lemonjuice<blood<NaOHsolution Q5. B Q5. pH Substance Q7. I. SolutionshavingpH= 6isacidic[solution 1 Batteryacid A].SolutionhavingpH= 8isbasic[solution 4 Applejuice B]. 7 Purewater 9 Toothpaste II. SolutionAhasmore[H+]ionconcentration. 14 Ovencleaner AspHdecreases,concentrationofH+ ions increases. Q9. pHwilldecrease. 10C02.5SALTSANDTHEIRPROPERTIES INCLASSEXERCISE II. Crystalsofsolidsaltarebrownincolour Q1. I. Sodiumchloride–Neutral duetoimpuritiesandarereferredtoas rocksalt. II. Ammoniumchloride–Acidic III.Sodiumacetate–Basic Q4. B Q2. Sodiumchloride(NaCl),Sodiumnitrate(NaNO3). Q5. Acidicsalts:Aluminium chloride,Zincsulphate, coppersulphate,ammoniumsulphate. Q3. SampleBandDwillshow equalvalueofpH Basicsalts:Sodiumacetate,sodiumcarbonate. becausebothareneutral. Neutral salts: Sodium chloride, potassium nitrate,sodiumsulphate. HOMEWORK Q6. The chemicalformula of hydrated copper Q1. Chemicalnamesoftwosaltsbelongingto: sulphate is CuSO4.5H2O. Hydrated copper sulphatecrystals–blue,andanhydrouscopper I. chloridefamily–Sodium Chloride(NaCl), sulphatecrystals–white. PotassiumChloride(KCl) Q11.C II. calcium Sfaumlpihlyat–e(CCaalcSiOu4m)Chloride(CaCl2), ADVANCEDQUESTIONS Calcium Q1. Classificationofsalts: Q2. Bakingsoda(NaHCO3)doesnotcontainwater ofcrystallization. Q3. Fillintheblanks: I. NaKSO4–Mixedsalt II. Cu(OH)Cl–Basicsalt I. Thesaltthatweuseinfoodismadebythe III.Na2SO4–Normalsalt base:NaOHandtheacid:HCl. Ans.

10C02–Acids,BasesandSalts 30 IV.FeSO4.(NH4)2SO4.6H2O–Doublesalt Q2. Hydrolysisofsalts: V. Cu(OH)NO3–Basicsalt I. FeCl3 + 3H2O→3HCl+ Fe(OH)3: Acidicsolution VI.NaHSO3–Acidsalt VII.Pb(OH)Cl–Basicsalt II. CH3COOK+ H2O→CH3COOH+ KOH: Basicsolution VIII.Na2HPO4–Acidsalt ( )IX.K2SO4.Al2 SO4 3.24H2O–Doublesalt 10C02.6COMMONSALTDERIVATIVES INCLASSEXERCISE Q1. I. Sodiumcarbonate(washingsoda)isusedtoremovepermanenthardnessofwater. II. Na2CO3 III.Itgetshydrated: Na2CO3 + 10H2O→Na2CO3.10H2O Q2. I. Bleachingpowerorcalciumoxychloride(CaOCl2). II. ItispreparedfromCa(OH)2bythefollowingreaction: Ca(OH)2+ Cl2 → CaOCl2+ H2O Bleaching powder Q3. I. Xishydrogen(H2)andYischlorine(Cl2). II. 2NaCl+2H2O →Electricity 2NaOH+Cl2+H2 III. Ca(OH)2 + Cl2→ CaOCl2 + H2O Dryslakedlime Bleachingpower Q4. X=Sodiumbicarbonateorsodiumhydrogencarbonate. ItsformulaisNaHCO3, Thereactioninvolvedis: 2NaHCO3(s) H→eat Na2CO3(s)+H2O(l)+CO2↑ X Q6. I. Bissodiumhydroxide(NaOH). II. NeutralisationreactionoccurswhenBistreatedwithanacidicoxide. Ans.

10C02–Acids,BasesandSalts 31 2NaOH+ CO2 → Na2CO3+ H2O III. (B) Sodium Water Carbondioxide Sodiumhydroxide (Acidicoxide) carbonate(salt) HOMEWORK Q2. Sodiumcarbonateisusedtomakeborax. Q3. Na2CO3 + 10H2O → Na2CO3.10H2O SodiumCarbonate washingsoda Q4. Bakingsodaispreparedusingcommonsaltasoneoftherawmaterials,accordingtothefollowingequation: NaCl+ CO2 + H2O+ NH3→NH4Cl+ NaHCO3 Q7. Inthegivensituation, I. XisNaHCO3,YisNa2CO3andZisNa2CO3.10H2O II. ThetwousesofcompoundZare: A) Asacleaningagentfordomesticpurpose. B) Forremovingpermanenthardnessofwater. Q8. ScaarltbAonisatbea(kNinag2CpOo3w)ei.re.(BNaaHndCOC3O)2wghasic,hi.eis.Ccoismemvoolnvleydu.sedinbakeryproducts.Onheating,itformssodium WhenCO2gasispassedthroughlimewater,itformscalciumcarbonate(CaCO3),whichisslightlysolublein watermakingitmilky. So,A:NaHCO3,B:Na2CO3,C:CO2gas 2NaHCO3(s)h→eatNa2CO3(s)+ H2O(l)+ CO2(g) Ca(OH)2(aq)+CO2(g) → CaCO3(s)+H2O(l) milky ADVANCEDQUESTIONS Q1. Thefirstreactionis 2NaCl+ H2SO4h→eatNa2SO4 + 2HCl Hence,XisNa2SO4. Now,limestoneisCaCO3andcoalisC.So,thesecondreactionis: Na2SO4 + CaCO3 + 2C→Na2CO3 + 2CO2 + CaS Q2. CaOCl2 + CO2→CaCO3 + Cl2 ADVANCEDPRACTICEPROBLEMS Ans.

10C02–Acids,BasesandSalts 32 Q2. I. SO24-isaLewisbase,asithasextraelectronsto V. Mg(HCO3)2 + 2HCl→MgCl2 + 2H2O+ 2C givetoH+.Thus,H+istheLewisacidhere. O2–Turnslimewatermilky II. Cl-isaLewisbase,asithasextraelectrons Q7. Acidity/Basicity togivetoNa+.Thus,Na+istheLewisacid. Q3. I. CuSO4 + 2H2O→H2SO4 + Cu(OH)2: I. Sulphurousacid(H2SO3)–Basicity-2 Acidicsolution II. Potassiumhydroxide–Acidity–1 II. CH3COONa+ H2O→CH3COOH+ NaOH: Basicsolution III.Chloricacid(HClO3)–Basicity–1 IV.NitrousAcid(HNO2)–Basicity-1 Q4. B V. Leadhydroxide–Acidity–2 Q5. B Q8. Buffersolutions Q6. Theequationswillbebalancedasshownbelow: I. 2Fe+ 6HCl→2FeCl3 + 3H2↑–Burnswitha i) Formic acid (HCOOH) and potassium popsound formate(HCOOK)–acidicbuffer II. KHSO3 + HCl→KCl+ H2O+ SO2–Turns acidifiedpotassiumdichromatesolution ii) Sodium hydrogen carbonateand sodium fromorangetogreen carbonate – acidic buffer [as sodium III.MgCO3 + 2HCl→MgCl2 + H2O+ CO2– hydrogencarbonatelosesanH+ tomake Turnslimewatermilky sodium carbonate,andhencebehaveslike IV.CdS+ 2HCl→CdCl2 + H2S–Smellslike anacid] rotteneggs iii)Citric acid and sodium citrate – acidic buffer iv)Carbonic acid and sodium hydrogen carbonate–acidicbuffer Ans.