Chapter 4 - Practice Exercise
Professor Kweyete
1. Specify how each of the following strong electrolytes ionizes or
dissociates into ions upon
dissolving in water.
a) KNO3 → K+ + NO3b) FeSO4 → Fe2+ + SO42c) (NH4)2CO3 → 2NH4+ + CO32d) NaHCO3 → Na+ + HCO32. 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 I
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+ + S2- → PbS
b) AgNO3 and KI
AgNO3 + KI → AgI + KNO3
Ag+ + NO3- + K+ + I- → AgI + NO3- + K+
Ag+ + I- → AgI
c) Na2CO3 and HCl
Na2CO3 + 2HCl → 2NaCl + H2CO3
2Na+ + CO32- + 2H+ + 2Cl- → 2Na+ + 2Cl- + H2CO3
CO32- + 2H+ → H2O + CO2
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:
b) C in C2O42-2 = 4(-2) + 2C
C = +3
d) P in H2PO4-1 = 4(-2) + 2(+1) + P
P = +5
a) Br in HBrO2
0 = 2(-2) + 1(+) + Br
Br = +3
c) C in COCl2
0 = -2 + 2(-1) + C
C = +4
6) Which element is oxidized (Reducing agent), and which is reduced
(Oxidizing agent) in the
following reactions?
a)
Cl2 R
+ 2NaBr O 
2NaCl + Br2
b)
Zn O
+
Zn Cl2
Cl2 R

c) Fe2O3 R + 3CO O
 2Fe
+ 3CO2
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
2AgNO3
CuO
NaF
2HCl
NR
 Zn(NO3 )2 + 2Ag
 H2O + Cu
NR
 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+2 ,0.5M Clb) 0.25 M C2H5OH => same
c) 0.20 M KCl + 0.25 M K2CO3 => 0.70M K+, 0.20M Cl-, 0.25M CO32d) 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 = 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.