Chapter 4 – Reactions in Aqueous Solutions
Dr. Pahlavan
1. Specify how each of the following strong electrolytes ionizes or dissociates into ions upon
dissolving in water.
a) KNO3
b) FeSO4
c) (NH4)2CO3
d) NaHCO3
2. Using solubility table, predict whether each of the following compounds is soluble or
insoluble in water:
a) NaCN
b) SrCO3
c) Pb(C2H3O2)2
d) Ag2S
3) Write balance complete molecular equation, ionic equation, and net ionic equations for the
reactions that occur when each of the following solutions are mixed. Identify the spectator
ion or ions in each reaction:
a) Pb(NO3)2 and Na2S
b) AgNO3 and KI
c) Na2CO3 and HCl
4) Classify each of the following as strong or weak acid or base:
a) HClO4
b) LiOH
c) NH3 as NH4OH
d) HCN
5) Determine the oxidation number for the indicated elements in each of the following
substances:
b) C in C2O42d) P in H2PO4-
a) Br in HBrO2
c) C in COCl2
6) Which element is oxidized (Reducing agent), and which is reduced (Oxidizing agent) in the
following reactions?
a) Cl2
+ 2NaBr 
2NaCl + Br2
b)
Zn
c) Fe2O3
+
Cl2

Zn Cl2
+ 3CO

2Fe
+
3CO2
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7) Using activity series table, what is the outcome of each of the following reactions? If no
reaction occurs, simply write NR.
a) Ag
b) Zn
c) H2
d) Br2
f) Co
+
+
+
+
+
Pb(NO3)2
AgNO3
CuO
NaF
HCl





8) Calculate the following quantities:
a) Molarity of a solution that contains 0.0225 mol Na2SO4 in 400 ml solution
b) Moles of HNO3 in 45.0 ml of 2.50 M solution of nitric acid
c) Milliliters of 2.00 M Ca(OH)2 solution needed to supply 0.250 mol of Ca(OH)2
9) Indicate the concentration of each ion present in the following solution:
a) 0.25 M BaCl2
b) 0.25 M C2H5OH
c) 0.20 M KCl + 0.25 M K2CO3
d) 20 ml of 0.20 M HCl + 10.0 ml of 0.500 M HCl
10) Calculate the following quantities:
a) milliliters of 0.75 M HCl required to neutralized completely 25.0 ml of 0.15 M Ba(OH)2
b) if 30.0 ml of 0.75 M HCl solution is needed to neutralize a solution of Ca(OH)2, how many
grams of Ca(OH)2 must be in the solution?
11) How would you prepare 100.0 ml of 0.045 M Na2SO4 solution starting with pure solid?
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Chapter 4– Reactions in Aqueous Solutions (answers)
Dr. Pahlavan
1. Specify how each of the following strong electrolytes ionizes or dissociates into ions upon
dissolving in water.
a) KNO3 (K+ + NO3- )
b) FeSO4 (Fe2+ + SO42-)
c) (NH4)2CO3 ( 2NH4+ + CO32-)
d) NaHCO3 ( Na+ + HCO3-)
2. Using solubility table, predict whether each of the following compounds is soluble or
insoluble in water:
a) NaCN (S)
b) SrCO3 (I) c) Pb(C2H3O2)2 (S)
d) Ag2S (I)
3) Write balance complete molecular equation, ionic equation, and net ionic equations for the
reactions that occur when each of the following solutions are mixed. Identify the spectator
ion or ions in each reaction:
a) Pb(NO3)2 and Na2S
Pb(NO3)2 + Na2S  PbS + 2NaNO3
Pb2+ + 2NO3- + 2Na+ + S2-  2Na+ + 2NO3- + PbS
Pb2+ (aq) + S2- 9aq)  PbS (s)
b) AgNO3 and KI
AgNO3 + KI  AgI + KNO3
Ag+ + NO3- + K+ + I-  AgI + NO3- + K+
Ag+ (aq) + I- (aq)  AgI (s)
c) Na2CO3 and HCl
Na2CO3 + 2HCl  2NaCl + H2CO3
2Na+ + CO32- + 2H+ + 2Cl-  2Na+ + 2Cl- + H2CO3
CO32- (aq) + 2H+ (aq)  H2O(l) + CO2(g)
4) Classify each of the following as strong or weak acid or base:
a) HClO4 (S) b) LiOH (S)
c) NH3 as NH4OH (W ) d) HCN (W)
5) Determine the oxidation number for the indicated elements in each of the following
substances:
a) Br in HBrO2  2(-2) + 1(+) + Br = 0  Br = +3
b) C in C2O42-  4(-2) + 2C = -2  C = +3
c) C in COCl2  -2 + 2(-1) + C = 0  C = +4
d) P in H2PO4-  4(-2) + 2(+1) + P = -1  P = +5
6) Which element is Oxidized (Reducing Agent), and which is Reduced (Oxidizing Agent) in the
following reactions?
a) Cl2 + 2NaBr  2NaCl + Br2
Cl2 (R) , Br ( O)
b) Zn + Cl2  Zn Cl2
Cl2 (R) , Zn ( O)
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c) Fe2O3 + 3CO  2Fe + 3CO2
Fe (R) , C( O)
7) Using activity series table, what is the outcome of each of the following reactions? If no
reaction occurs, simply write NR.
a) Ag + Pb(NO3)2  NR
c) H2 + CuO  H2O + Cu
b) Zn + 2AgNO3  Zn(NO3 )2 + 2Ag
, d) Br2 + NaF
NR
f) Co + 2HCl  CoCl2 + H2
8) Calculate the following quantities:
a) Molarity of a solution that contains 0.0225 mol Na2SO4 in 400 ml solution.
M = 0.0225 mol = 0.0563M
0.4L
b) Moles of HNO3 in 45.0 ml of 2.50 M solution of nitric acid
2.50 mol│ 0.045L = 0.113 mole
L │
c) Milliliters of 2.00 M Ca(OH)2 solution needed to supply 0.250 mol of Ca(OH)2
1L
│0.25 mol = 0.125L = 125 ml
2 mol │
9) Indicate the concentration of each ion present in the following solution:
a) 0.25 M BaCl2 (0.25M Ba+ ,0.5M Cl-)
b) 0.25 M C2H5OH  0.25 M (not ionic)
c) 0.20 M KCl + 0.25 M K2CO3  (0.20 + 2x0.25 = 0.45 ) M K+, 0.20M Cl-, 0.25M CO32-)
d) 20 ml of 0.20 M HCl + 10.0 ml of 0.500 M HCl
20ml(0.2M) + 10ml(0.5M) = 0.3M H+ & 0.3M Cl20ml + 10ml
10) Calculate the following quantities:
a) milliliters of 0.75 M HCl required to neutralized completely 25.0 ml of 0.15 M Ba(OH)2
1(0.75M)Va = 2(0.15M)(25 ml); Va = 10 ml
b) if 30.0 ml of 0.75 M HCl solution is needed to neutralize a solution of Ca(OH)2, how many
grams of Ca(OH)2 must be in the solution?
1(30ml)(0.75M) = 2MbVb; MbVb = 0.0113 mole;  g mass = 0.0113(74g/mol) = 0.84g
11) How would you prepare 100.0 ml of 0.045 M Na2SO4 solution starting with pure solid?
0.045M(0.1L) = 0.0045mole; mol wt = 142g/mol  0.0045(142) = 0.64g
So weigh out 0.64g of solid, place in a 100ml volumetric flask and add water to the 100ml mark to
make the solution.
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