BCLN CHEMISTRY 11 - Rev. July/2014
Unit 3 ~ Learning Guide Name: ______________________________
Instructions:
Using a pencil, complete the following notes as you work through the related lessons. Show ALL
work as is explained in the lessons. You are required to have this package completed BEFORE
you write your unit test. Do your best and ask questions if you don’t understand anything!
Please print out the Formula Sheet and found at the start of the course. You will need this
to do assignments and tests!
Solubility:
1. What is the difference between a homogeneous mixture and a heterogeneous mixture?
In a homogeneous mixtures the components are uniformly distributed while in a
heterogeneous mixture they are segregated when at rest.
2. What do you think will happen if more solute is added to a saturated solution in flask?
It will not dissolve. Students may say the solute will settle to the bottom of the flask as a
precipitate.
3. What is the concentration we use to determine if a substance is soluble or has low solubility in a
solvent?
0.100 M
4. What is the equation for solubility(s) in relation to Ksp for a 1:1:1 reaction? Rearrange this to
determine the equation for Ksp in terms of solubility (s).
𝐬 = √𝐊 𝐬𝐩
𝐊 𝐬𝐩 = 𝐬𝟐
5. What is the equation for solubility(s) in relation to Ksp for a 1:2:1 or 1:1:2 reaction? Rearrange
this to determine the equation for Ksp in terms of solubility (s).
𝟑
𝐬= √
𝐊 𝐬𝐩
𝟒
𝐊 𝐬𝐩 = 𝟒𝐬𝟑
6. What is the equation for solubility(s) in relation to Ksp for a 1:1:3 or 1:3:1 reaction? Rearrange
this to determine the equation for Ksp in terms of solubility (s).
𝟒
𝐬= √
𝐊 𝐬𝐩
𝟐𝟕
𝐊 𝐬𝐩 = 𝟐𝟕𝐬𝟒
Page 1 of 9
BCLN CHEMISTRY 11 - Rev. July/2014
7. Look up the Ksp of strontium carbonate in your data booklet. Write the dissociation equation for
this compound, determine what ratio it is and then calculate its solubility.
SrCO3(s)  Sr2+(aq) + CO32-(aq)
Ksp = 5.6 x 10-10
1:1:1 reaction
𝐬 = √𝐊 𝐬𝐩 = √𝟓. 𝟔 𝐱 𝟏𝟎−𝟏𝟎 = 𝟐. 𝟒 𝐱 𝟏𝟎−𝟓 M
8. The Ksp of Sc(OH)3 is 8.0x10-31. Write the dissociation equation for this compound, determine
what ratio it is and then calculate its solubility.
Sc(OH)3(s)  Sc3+(aq) + 3 OH-(aq)
Ksp = 8.0 x 10-31
1:1:3 reaction
𝟒
𝐬= √
𝐊 𝐬𝐩
𝟐𝟕
𝟒
𝟖.𝟎 𝐱 𝟏𝟎
= √
𝟐𝟕
−𝟑𝟏
= 𝟏. 𝟑 𝐱 𝟏𝟎−𝟖 M
9. The solubility of NiS(s) is 5.5 x 10-10 M at 25°C.Write the dissociation equation and calculate Ksp.
NiS(s)  Ni2+(aq) + S2-(aq)
𝐊 𝐬𝐩 = 𝐬𝟐 = (𝟓. 𝟓 𝐱 𝟏𝟎−𝟏𝟎 )𝟐 =3.0 𝐱 𝟏𝟎−𝟏𝟗
10. The solubility of copper (II) hydroxide is 1.8 x 10-7 M at 25°C.Write the dissociation equation
and calculate Ksp.
Cu(OH)2(s)  Cu2+(aq) + 2 OH-(aq)
𝐊 𝐬𝐩 = 𝟒𝐬𝟑 = 𝟒(𝟏. 𝟖 𝐱 𝟏𝟎−𝟕 )𝟑 =2.3 𝐱 𝟏𝟎−𝟐𝟎
Page 2 of 9
BCLN CHEMISTRY 11 - Rev. July/2014
11. A 500. L sample of saturated silver bromide is evaporated to dryness. What is the mass of the
solid residue?
AgBr(s)  Ag+(aq) + Br-(aq)
Ksp = 5.4 x 10-13
1:1:1 reaction
𝐬 = √𝐊 𝐬𝐩 = √𝟓. 𝟒 𝐱 𝟏𝟎−𝟏𝟑 = 𝟕. 𝟑𝟓 𝐱 𝟏𝟎−𝟕 M
Molar Mass AgBr = 1Ag + 1Br = 107.9 + 79.9 = 187.8 g/mol
𝟕.𝟑𝟓 𝐱 𝟏𝟎−𝟕 𝐦𝐨𝐥 𝐀𝐠𝐁𝐫
𝟓𝟎𝟎. 𝐋 𝐀𝐠𝐁𝐫 ×
𝟏 𝐋 𝐀𝐠𝐁𝐫
×
𝟏𝟖𝟕.𝟖 𝐠 𝐀𝐠𝐁𝐫
𝟏 𝐦𝐨𝐥 𝐀𝐠𝐁𝐫
= 𝟎. 𝟎𝟔𝟗 𝐠
12. A 500. L sample of saturated copper(II) iodate is evaporated to dryness. What is the mass of the
solid residue?
Cu(IO3)2(s)  Cu2+(aq) + 2IO3-(aq)
Ksp = 6.9 x 10-8
1:1:2 reaction
𝟑
𝐬= √
𝐊 𝐬𝐩
𝟒
𝟑
𝟔.𝟗 𝐱 𝟏𝟎
= √
𝟒
−𝟖
= 𝟐. 𝟓𝟖 𝐱 𝟏𝟎−𝟑 M
Molar Mass Cu(IO3)2 = 1Cu + 2I + 6O = 63.5 + 2(126.9) + 6(16.0) = 413.3 g/mol
𝟓𝟎𝟎. 𝐋 𝐂𝐮(𝐈𝐎𝟑 )𝟐 ×
𝟐.𝟓𝟖 𝐱 𝟏𝟎−𝟑 𝐦𝐨𝐥 𝐂𝐮(𝐈𝐎𝟑 )𝟐
𝟏 𝐋 𝐂𝐮(𝐈𝐎𝟑 )𝟐
Page 3 of 9
×
𝟒𝟏𝟑.𝟑 𝐠 𝐂𝐮(𝐈𝐎𝟑 )𝟐
𝟏 𝐦𝐨𝐥 𝐂𝐮(𝐈𝐎𝟑 )𝟐
= 𝟓𝟑𝟎 𝐠
BCLN CHEMISTRY 11 - Rev. July/2014
13. A solution which contains only one of the following anions: I-, SO42-, or OH- is tested with
various reagents and the following results are obtained:
Reagent
Result
0.2 M AgNO3
Precipitate
0.2 M Fe(NO3)2
Precipitate
0.2 M Sr(NO3)2
No precipitate
a) Which anion does the solution contain?
OHb) Explain why each of the other two ions is not the ion in the solution.
I- would not form a precipitate with Fe2+
SO42- not form a precipitate with Fe2+ but would form a precipitate with Sr2+
14. A solution which contains only one of the following cations: Ag+, Pb2+, or Cu+ is tested with
various reagents and the following results are obtained:
Reagent
Result
0.2 M NaCl
Precipitate
0.2 M Na2SO4
No Precipitate
0.2 M NaNO3
No precipitate
a) Which cation does the solution contain?
Cu+
b) Explain why each of the other two ions is not the ion in the solution.
Both Ag+ and Pb2+ would form precipitates with SO42-. Also Pb2+ would not form a
precipitate with Cl–.
Page 4 of 9
BCLN CHEMISTRY 11 - Rev. July/2014
15. If 120. mL of 0.000125 M AgNO3 and 70.0 mL of 0.000250 M K2CO3 are combined, will a
precipitate form? Use the table below to help you reach your answer. Start by filling in the
correct dissociation equation for the possible precipitate.

Ag2CO3(aq)
[Initial]
-
[Trial]
-
2 Ag+(aq)
(𝟎. 𝟎𝟎𝟎𝟏𝟐𝟓𝐌)
𝟏𝟐𝟎 𝐦𝐋
𝟏𝟗𝟎 𝐦𝐋
CO32-(aq)
+
(𝟎. 𝟎𝟎𝟎𝟐𝟓𝟎𝐌)
0.0000789 M
𝟕𝟎 𝐦𝐋
𝟏𝟗𝟎 𝐦𝐋
0.0000921 M
𝐓𝐫𝐢𝐚𝐥 𝐊 𝐬𝐩 = [𝐀𝐠 + ]𝟐 [𝐂𝐎𝟑 𝟐− ] = (𝟎. 𝟎𝟎𝟎𝟎𝟕𝟖𝟗)𝟐 (𝟎. 𝟎𝟎𝟎𝟎𝟗𝟐𝟏)
𝐓𝐫𝐢𝐚𝐥 𝐊 𝐬𝐩 = 𝟓. 𝟕𝟑 𝐱 𝟏𝟎−𝟏𝟑
𝐊 𝐬𝐩 = 𝟖. 𝟓 𝐱 𝟏𝟎−𝟏𝟐
𝐓𝐫𝐢𝐚𝐥 𝐊 𝐬𝐩 < 𝐊 𝐬𝐩 . 𝐓𝐡𝐞𝐫𝐞𝐟𝐨𝐫𝐞 𝐚 𝐩𝐫𝐞𝐜𝐢𝐩𝐢𝐭𝐚𝐭𝐞 𝐰𝐢𝐥𝐥 𝐍𝐎𝐓 𝐟𝐨𝐫𝐦.
16. Given a 0.00500 M solution of KOH, what concentration of Mg(NO3)2 will be needed to just
start precipitation of Mg(OH)2? First write the dissociation equation for the precipitate then use
the Ksp equation for the precipitate. There is no dilution effect in this situation as the amount
added is very small.
Mg(OH)2(s)  Mg2+(aq) + 2 OH-(aq)
𝐊 𝐬𝐩 = [𝐌𝐠 𝟐+ ][O𝐇 − ]𝟐
𝟓. 𝟔 𝐱 𝟏𝟎−𝟏𝟐 = [M𝐠 𝟐+ ](0.005𝟎𝟎)𝟐
 Mg  


2
5.6  10 12
 0.00500 
2
 2.2  10 7 M
Page 5 of 9
Ksp = 5.6 x 10-12
BCLN CHEMISTRY 11 - Rev. July/2014
17. Fill in each box in the following table with either Increased solubility or Decreased solubility
Reaction Type
Exothermic
Endothermic
Temperature Increases
Decreased solubility
Increased solubility
Temperature Decreases
Increased solubility
Decreased solubility
18. For the following equilibrium, determine whether adding each of the following compounds will
increase solubility, decrease solubility or have no effect.
CuCl2(s)  Cu2+(aq) + 2 Cl-(aq)
Compound Added
Effect on solubility of CuCl2
NaCl
Decrease
Cu(NO3)2
Decrease
CuCl2
No effect
KI
Increase
Saturated Solutions:
1. Explain why a saturated solution with NO solid present is NOT at equilibrium.
If there is no solid present then no dissolving is taking place. Therefore, you do not have a
balance between the opposing processes of dissolving and precipitation, which is the
definition of solubility equilibrium.
2. Which of the following saturated solutions will have the lowest [Sr2+]? Explain how you know.
Strontium carbonate
Strontium fluoride
Strontium suphate
Compound
Formula
Ratio:
Formula for “s”
2+
[Sr ] = s
strontium carbonate
SrCO3
1:1:1
strontium fluoride
SrF2
1:1:2
s  Ksp
5.6  1010  2.4  105 M
s
3
K sp
s  Ksp
4
4.3  10 9
 1.0  10 3 M
4
So [Sr2+] would be lowest in strontium carbonate.
Page 6 of 9
3
strontium sulphate
SrSO4
1:1:1
3.4  107  5.8  104 M
BCLN CHEMISTRY 11 - Rev. July/2014
3. When do you stop adding solution from your burette when doing a titration?
When you observe a color change.
Ions:
1. When you are separating ions using filtration, what is the name of the solution that passes through
the filter?
The filtrate
2. For each pair of ions given on the left, circle an ion which could be added in order to allow for
separation of the ions on the left.
Ions to be separated
Circle the correct ion
Cu+ and Na+
Cl-
SO42-
NO3-
Sr2+ and Pb2+
PO43-
SO42-
OH-
S2- and OH-
Sr2+
Mg2+
Ag+
3. Write a net ionic equation for each precipitate that forms in question 2.
Cu+(aq) +
Cl-(aq)  CuCl(s)
Pb2+(aq) + 2OH-(aq)  Pb(OH)2(s)
Mg2+(aq) + 2OH-(aq)  Mg(OH)2(s)
4. What concentration of silver bromate can dissolve in 0.0020 M sodium bromate?
AgBrO3(s)  Ag+(aq) + BrO3-(aq)
𝐊 𝐬𝐩 = [A𝐠 + ][BrO3-]
𝟓. 𝟑 𝐱 𝟏𝟎−𝟓 = [A𝐠 + ][0.0020]
5.3  105
 AgBrO3    Ag   0.0020  0.027 M

Page 7 of 9
Ksp = 5.3 x 10-5
BCLN CHEMISTRY 11 - Rev. July/2014
5. What concentration of lead(II) iodide can dissolve in 3.00 M potassium iodide?
PbI2(s)  Pb2+(aq) + 2I-(aq)
Ksp = 8.5 x 10-9
𝐊 𝐬𝐩 = [P𝐛𝟐+ ][𝐈− ]𝟐
𝟖. 𝟓 𝐱 𝟏𝟎−𝟗 = [P𝐛𝟐+ ][3.00]𝟐
 PbI 2    Pb 2  
8.5  10 9
 3.00 
 9.4  10 10 M
2
6. What concentration of iron(III) hydroxide can dissolve in 4.0 x 10-12 M potassium hydroxide?
Fe(OH)3(s)  Fe3+(aq) + 3OH-(aq)
Ksp = 2.6 x 10-39
𝐊 𝐬𝐩 = [𝐅𝐞𝟑+ ][O𝐇 − ]𝟑
𝟐. 𝟔 𝐱 𝟏𝟎−𝟑𝟗 = [𝐅𝐞𝟑+ ][ 𝟒. 𝟎 𝐱 𝟏𝟎−𝟏𝟐 ]𝟑
 Fe  OH     Fe 3  
3



2.6  10 39
 4.0  10 
12 3
 4.1  10 5 M
7. A large vessel contains 250. L of 0.00030 M barium sulfide (BaS). What mass of solid sodium
carbonate (Na2CO3) would be needed to just start precipitation of barium carbonate (BaCO3)?
BaCO3(s)  Ba2+(aq) + CO32-(aq)
Ksp = 2.6 x 10-9
𝐊 𝐬𝐩 = [B𝐚𝟐+ ][CO32-]
𝟐. 𝟔 𝐱 𝟏𝟎−𝟗 = [0.00030] [CO32-]
 CO23 


2.6  109

 8.67  106 M
0.00030
Molar Mass Na2CO3 = 2(Na) + 1(C) + 3(O) = 2(23.0) + 1(12.0) + 3(16.0) = 106.0 g/mol
𝟐𝟓𝟎. 𝐋 𝐂𝐎𝟑
𝟐−
×
𝟖.𝟔𝟕 𝐱𝟏𝟎−𝟔 𝐦𝐨𝐥 𝐂𝐎𝟑 𝟐−
𝟏 𝐋 𝐂𝐎𝟑
𝟐−
×
= 0.23 g Na2CO3 would be required.
Page 8 of 9
𝟏 𝐦𝐨𝐥 𝐍𝐚𝟐 𝐂𝐎𝟑
𝟏 𝐦𝐨𝐥 𝐂𝐎𝟑
𝟐−
×
𝟏𝟎𝟔.𝟎 𝐠 𝐍𝐚𝟐 𝐂𝐎𝟑
𝟏 𝐦𝐨𝐥 𝐍𝐚𝟐 𝐂𝐎𝟑
BCLN CHEMISTRY 11 - Rev. July/2014
8. A large vessel contains 500. L of 0.00050 M silver nitrate (AgNO3). What mass of solid
ammonium chromate ((NH4)2CrO4) would be needed to just start precipitation of silver chromate
(Ag2CrO4)?
A𝐠 𝟐 CrO4(s)  2Ag+(aq) + CrO42-(aq)
Ksp = 1.1 x 10-12
𝐊 𝐬𝐩 = [A𝐠 + ]𝟐 [CrO42-]
𝟏. 𝟏 𝐱 𝟏𝟎−𝟏𝟐 = [0.00050]𝟐 [CrO42-]
[CrO42-]=
𝟏.𝟏 𝐱 𝟏𝟎−𝟏𝟐
(𝟎.𝟎𝟎𝟎𝟓𝟎)𝟐
= 4.4 𝐱 𝟏𝟎−𝟔 M
Molar Mass (NH4)2CrO4 = 2(N) + 8(H) + 1(Cr) + 4 O
= 2(14.0) + 8(1.0) + +1(52.0) + 4(16.0) = 152.0 g/mol
𝟓𝟎𝟎. 𝐋 𝐂𝐫𝐎𝟒 𝟐− ×
𝟒.𝟒 𝐱𝟏𝟎−𝟔 𝐦𝐨𝐥 𝐂𝐫𝐎𝟒 𝟐−
𝟏 𝐋 𝐂𝐫𝐎𝟒
𝟐−
×
𝟏 𝐦𝐨𝐥 (𝐍𝐇𝟒 )𝟐 𝐂𝐫𝐎𝟒
𝟏 𝐦𝐨𝐥 𝐂𝐫𝐎𝟒
𝟐−
×
𝟏𝟓𝟐.𝟎 𝐠 (𝐍𝐇𝟒 )𝟐 𝐂𝐫𝐎𝟒
𝟏 𝐦𝐨𝐥 (𝐍𝐇𝟒 )𝟐 𝐂𝐫𝐎𝟒
= 0.33 g (NH4)2CrO4
Answers:
Solubility:
7. 2.4 x 10-5 M
8. 1.3 x 10-8 M
9. 3.0 x 10-19
11. 0.069 g
12. 530 g
15. Trial Ksp = 5.73 x 10-13
4. 0.027 M
5. 9.4 x 10-10 M
6. 4.1 x 10-5 M
7. 0.23 g
8. 0.33 g
16. 2.2 x 10-7 M
Ions:
Page 9 of 9
10. 2.3 x 10-20