Chemistry12SolubilityEquilibriumIII

Name:Date:Block:

1. OneSourcevs.TwoSourceSolubility

Problems2. ChallengingSolubilityProblems3. PredictionofFormingaPrecipitate

OneSourcevs.TwoSourceSolubilityProblems

OneSource TwoSource• Bothionscomefromthesamesalt(source)

Mg(OH)2(s)⇋Mg2+(aq)+2OH-(aq)

• Bothionscomefromadifferentsalt(source)MgS(s)⇋Mg2+(aq)+S2-(aq) NaOH(s)⇋Na+(aq)+OH-(aq)

Mg(OH)2(s)⇋Mg2+(aq)+2OH-(aq)

• Ionconcentrationsarerelatedthroughmoleratiov 1:1ratio=

v 1:2ratio=

v 1:3ratio=

v 2:3ratio=

• RelatedthroughKsp• Ex:Findthe[OH-]if[Mg2+]=4.5x10-3M.

ChallengingSolubilityProblemsAsolutionhasaconcentrationofcalciumionsequalto2.5x10-2M.Whatisthemaximumconcentrationofsulphateionsallowedwithoutcausingprecipitation?

s s 25 X Yksp Mg2tCOH72

5 as 2 453 X yKsp_Cmg'tfoH32 4 y

S2Mglothes Mgitag t 20 Tag

453Ksp CMgztTCoH72 5.6 10 12

2754 A10855

OH gantry4 5 10 3

saturatedhe

Casoyes Calctag t 50472g2.5 102M

soup 7 7.1 15Ksp Catcsai 7 2.5 10 27 1 10 5 2.5 10 2 Soy I

42.8 1032

When100.0mLof4.0x10-2MCaCl2isaddedto150.0mLof2.9x10-2MNaOH,aprecipitatejuststartstoform.WhatistheKspofthisprecipitate?

• Writea(balanced)doublereplacementreaction.

• Whatisthepossibleprecipitate?WritetheKspexpression.

• Calculatethedilutedconcentrationsofeachion.

• CalculatetheKspvalue.

Saturated

CaClzt2NaoH cacoHlyji

qvaqea9gjmexisB.caCoHkes I CaZTag t 20h capCa2t CoH 2

NDOH C V CzVz44 7 too Yano camo rooted0.016 M Ct O 017M

i o m

Ksp Kat It 720.016 0.01772

146 1067

Upto15.0gofBaCl2canbedissolvedin2.5LofAl2(SO4)3withoutaprecipitatebeingformed.Find[Al2(SO4)3].

• Writethedoublereplacementreaction.(Whatisthesolute?Whatisthesolvent?)

• Whatisthepossibleprecipitatethatcouldbeformed?WritetheKspexpressionanddetermineitsvaluefromthedatabooklet.

• LookingattheKspexpression,isthereanionconcentrationvaluethatcouldbedetermined?

Worksheet3.3

36312 t As sf t2Ak bagppt

Basoyes I Battagst SOYTagKsp CBat 27 1.1 10 10

from tabu

fi

c

Soy'T I.lxO 029

3.8 10 9M

AIz Soy 2A13 350423.8 10 9M

I 7

PredictionofFormingaPrecipitateWhentwodifferentsolutionsaremixed,wecanpredictwhetheraprecipitatewillform.TheKspvaluerepresentsthemaximumproductoftheionconcentrationsinasaturatedsolution.

• Iftheproductoftheionconcentrationspresentexceedsthisvalue,theionswillnotremaindissolvedinsolutionandaprecipitatewillform.

• IftheproductoftheionconcentrationsislessthanthevalueofKsp,theionsremaindissolvedinsolution,andnoprecipitateforms.

Ifanequilibriumisnotpresentinsolution,thenwecalculateatrialionproduct(TIP)–(alsocalledatrialKspvalueorreactionquotient,Q)

IfTIP>Ksp–aprecipitateforms.

IfTIP<Ksp–noprecipitateforms.

IfTIP=Ksp–thesolutionissaturated.

Example.(1)Willaprecipitateformwhen23mLof0.020MNa2CO3isaddedto12mLof0.010MMgCl2?

• Writeabalancedequation.Whatistheprecipitatethatwillpotentiallyform?(Usethesolubilitytable):

• Whataretheconcentrationsofeachoftheseions?

• CalculatethevalueofTIP

• ComparetheTIPwiththerealKsp.Willaprecipitateform?

saturated

Nazca t Mgclz M t2Na4cag

Nao omg za

IV CzVz CN CzVz0.9230123 Cz 10.0101

C 0.013mg Cz 0 0 4 M

Mgco es T MgYog t CosbyMP Mgk cop 0.0034 0.013 4

actual Ksp 6.8 10 6

IMPSKspipptwillforin

(2)Willaprecipitateformwhen8.5mLof6.3x10-2Mlead(II)nitrateisaddedto1.0Lof1.2x10-3Msodiumiodate?(3)Willaprecipitateformwhen1.5mLof4.5x10-3Mammoniumbromateisaddedto120.5mLof2.5x10-3Msilvernitrate?HebdenWorkbookPg.98#56-69

0.0085L0

Pb Nos z t 2NdOz 2NANOSCag t PbCl0

FEI Imus

g

watt ios atCN Czk 1.2 103M

6.3 10 2 0.0085 CN Czkp 122 10

5 5.3 104M 1.00852 1.2 103M

Pbc103z Pb t 2105TIP CPb2t 10372TIP 5.3 1.04 1.2 10 3TIP 7.6 10 10

Actual Ksp 3.7 10 13 ITPSKsp.ipptwilltori

NHyBrons t Agnes T t NH4N03capppteEm E

io.myEIfos.sIgf7stxiotsN5cz4.5 10 3 1.5

Cz 2.5 10 3 120.5Cz 5.5 105M 122.02 2.5 10 3M

AyBrozes Agtag t BrozcogTIP Agt BrosTIP 2.5 10 3 5.5 10 5TIP 1.4 xie 7

µpcksp pptwiHNoforJActual Ksp_5.3 10 5

finish worksheet 3.3