AP Chem Review Sheet Ch. 4,13
Reactions in Aqueous Solution & Equilibrium
1. Nitric Acid, HNO3, and strontium hydroxide, Sr(OH)2, are a strong acid and a strong
base, respectively. They participate in a variety of acid-base reactions with other
species. In addition, nitric acid is often involved in redox reactions because the NO3- ion
is readily reduced. Finally, strontium hydroxide can form precipitates involving the
Sr2+ ion or the OH- ion.
a. Write the equation for the reaction between solutions of
(1) strontium hydroxide and aluminum nitrate
(2) nitric acid and ammonia
(3) strontium hydroxide and nitric acid
(4) strontium hydroxide and acetic acid (HC2H3O)
(5) nitric acid and Cu(s) forming nitrogen oxide gas and copper (II) ion.
b. When 15.00 mL of 0.2050 M strontium hydroxide reacts with 22.00 mL of 0.1380 M
cobalt (III) sulfate, two precipitates form. Calculate the mass of each precipitate and the
concentrations of all ions after reaction, assuming th final volume is the sum of the initial
volumes.
c. Nitric acid is used to analyze a sulfide ore; S2- ions are oxidized to sulfur, while NO3- ions
are reduced to NO (g). It is found that 64.5 mL of a solution 0.125 M in NO3- is required
to react exactly with a 1.00 g sample of ore. Calculate the percent of sulfur in the ore.
d. To determine the molarity of a solution of hydrobromic acid, it is titrated with 0.2384 M
strontium hydroxide. It is determined that 20.50 mL of strontium hydroxide is required
to react with 33.20 mL of hydrobromic acid. What is the molarity of the hydrobromic
acid?
2. Consider bromine chloride, an interhalogen compound. It is formed by the reaction
between red-orange bromine vapor and yellow chlorine gas; BrCl is itself a gas. The
reaction is endothermic.
a. Write the chemical equation for the formation of BrCl, using simplest whole-number
coefficients.
b. Write the equilibrium expression for Kc.
c. At 400°C, after the reaction reached equilibrium, the mixture contained 0.82 M BrCl, 0.20
M Br2 and 0.48 M Cl2. Calculate Kc for the reaction.
d. Write the equilibrium expression for Kp.
e. What is Kp at 400°C?
f. Initially, a 2.00-L flask contains Cl2 with partial pressure 0.51 atm and Br2 with partial
pressure 0.34 atm. After equilibrium is established, the partial pressure of BrCl is 0.46
atm. Calculate the equilibrium pressures of Cl2 and Br2.
g. Initially, a 2.00-L reaction vessel contains 0.15 mol of each gas. In what direction will the
reaction proceed? What are the equilibrium concentrations of each gas after equilibrium is
established? If 0.050 mol BrCl are added, in what direction will equilibrium shift? What
are the equilibrium concentrations after equilibrium has been re-established?
h. In what direction will the system shift if at equilibrium
(1) the volume is increased?
(2) helium gas is added?
(3) the temperature is increased?
ANSWERS:
1. a.
(1) Al3+ (aq) + 3 OH- (aq)  Al(OH)3 (s)
(2) H+ (aq) + NH3 (aq)  NH4+ (aq)
(3) H+ (aq) + OH- (aq)  H2O
(4) HC2H3O2 (aq) + OH- (aq)  H2O + C2H3O2- (aq)
(5) 2 NO3- (aq) + 8 H+ (aq) + 3 Cu (s)  2 NO (g) + 4 H2O + 3 Cu2+ (aq)
b. ~0 moles Sr2+ and OH-, 0.5646 g SrSO4, 0.2254 g Co(OH) 3;
0.1631 M SO42-; 0.1087 M Co3+
c. 38.8%
d. 0.2944 M
2. a. 2 Br2 (g) + Cl2 (g) <==> 2 BrCl (g)
b. Kc = [BrCl]2 /[Br2][Cl2]
c. 7.0
d. Kp = (PBrCl)2 /(PBr2)(PCl2)
e. 7.0
f. 0.28 atom; 0.11 atm
g.  ; [Br2] = [Cl2] = 0.054 M, [BrCl] = 0.142 M
h. (1) no change; (2) no change; (3) 