Chemistry 12 Solubility Equilibrium III Name: Date: Block: 1. One Source vs. Two Source Solubility Problems 2. Challenging Solubility Problems 3. Prediction of Forming a Precipitate One Source vs. Two Source Solubility Problems One Source Two Source • Both ions come from the same salt (source) Mg(OH)2(s) ⇋ Mg 2+ (aq) + 2 OH - (aq) • Both ions come from a different salt (source) MgS(s) ⇋ Mg 2+ (aq) +S 2- (aq) NaOH(s) ⇋ Na + (aq) + OH - (aq) Mg(OH)2(s) ⇋ Mg 2+ (aq) + 2 OH - (aq) • Ion concentrations are related through mole ratio v 1:1 ratio = v 1:2 ratio = v 1:3 ratio = v 2:3 ratio = • Related through Ksp • Ex: Find the [OH - ] if [Mg 2+ ] = 4.5 x 10 -3 M. Challenging Solubility Problems A solution has a concentration of calcium ions equal to 2.5 x 10 -2 M. What is the maximum concentration of sulphate ions allowed without causing precipitation? s s 25 X Y ksp Mg2t COH 72 5 as 2 453 X y Ksp _Cmg't foH 32 4 y S2 Mglothes Mgitag t 20 Tag 453 Ksp CMgztTCoH 72 5.6 10 12 2754 A 10855 OH gantry 4 5 10 3 saturated he Casoyes Calctag t 50472g 2.5 10 2M soup 7 7.1 15 Ksp Catcsai 7 2.5 10 2 7 1 10 5 2.5 10 2 Soy I 42.8 10 32
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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
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