Download Equilibrium Practice Problems Acids and Bases Practice Problems

Equilibrium Practice Problems
1. Write the equilibrium expression for the following
reaction: 2 NO2 (g) + 2 H2 (g) ↔ N2 (g) + 2 H2O (g).
4. What is the concentration of hydroxide ions in a
saturated solution of Al(OH)3 (Ksp = 3 X 10-34)?
2. The value of the equilibrium constant K is dependent
on
(a) The temperature of the system
(b) The initial concentration of the reactants
(c) The initial concentration of the products
(d) all of the above
(e) none of the above
5.
At a certain temperature the equilibrium constant
for the reaction, PCl5 (g) ↔ PCl3 (g) + Cl2 (g), is
equal to 33. Initially, 2.0 mol PCl5 are placed in a
1.0 L container. Find the number of moles of PCl5,
PCl3, and Cl2 when equilibrium is established.
6. Find the solubility AgBr in mol/L at 25°C (Ksp = 5.0
X 10-13).
3. Consider the system below at equilibrium. Which of
the following changes will shift the equilibrium to the
right? (Circle all that apply.)
N2 (g) + 3 H2 (g) ↔ 2 NH3 (g) + 93 kJ
(a) Increasing the temperature
(b) Decreasing the temperature
(c) Increasing the pressure
(d) Decreasing the pressure
(e) Increasing the volume of the container
(f) Decreasing the volume of the container
Acids and Bases Practice Problems
1. What will be the pH at the equivalence point for
NaOH being titrated with HCH3CO2?
(a) acidic
(b) basic
(c) 7
(d) Not enough information
2. What condition must be satisfied to make a good
buffer?
(a) You must mix a strong acid with its conjugate
base.
(b) You must mix a weak acid with its conjugate
base.
(c) The ratio of base to acid must be around 10.
(d) The ratio of base to acid must be around 1.
3. What is the pH of a 1.0 M solution of NaCl in water?
(a) 5.5
(b) 7
(c) 8.5
(d) 0
4. Which of the following has the most impact on the
acidity of a halogen acid, HX?
(a) the electronegativity of X
(b) the strength of the H-X bond
(c) the electron affinity of X
(d) the ionization potential of H
5. Which of the following is NOT a valid definition of
an acid?
(a) an electron pair acceptor
(b) a substance that lowers the pOH of a solution
(c) a proton donor
(d) a substance that produces H+ in solution
6. What is the ratio of [H3O+] for a pH 4 solution to
[H3O+] for a pH 7 solution?
7. For each of the following choices, choose that which
describes the weaker acid:
(a) Ka = X or Ka = 3X
(b) [H3O+] = X or [H3O+] = 3X
(c) pH = X or pH = 3X
8. What is the molecular weight of a diprotic acid
solution (5.0 g in 100.0 mL) that is neutralized by
50.0 mL of a 1.0 M NaOH solution?
9. What is the pH of a 0.100 M solution of cacodylic
acid (Ka = 6.4 X 10-7)?
Thermo Practice Problems
1. Calculate ΔH for the formation of 1 mole of PbSO4(s)
from its elements, given the following:
Pb(s) + S(s) → PbS(s) + 94 kJ/mol
PbS(s) + 2O2(g) → PbSO4(s) + 824 kJ/mol
(a) –730 kJ/mol
(b) +730 kJ/mol
(c) +918 kJ/mol
(d) –918 kJ/mol
(e) none of the above
2. As a result of an exothermic reaction,
(a) the energy of the system is decreased and the
energy of the surroundings is increased.
(b) the energy of the system and the energy of the
surroundings are decreased.
(c) the energy of the system is increased and the
energy of the surroundings are decreased.
(d) the energy of the system and the energy of the
surroundings are increased.
(e) None of these answers are accurate.
3. A bomb calorimeter has a heat capacity of 3.18 kJ/K.
When 0.0038 mol of a gas is burned in the calorimeter,
the temperature increased from 25.0°C to 27.3°C.
Calculate the energy released by the combustion of one
mole of the gas.
(a) 2.8 x 10-2 kJ
(b) 7.3 kJ
(c) 1.9 x 103 kJ
(d) 1.9 x 10-2 kJ
(e) 3.6 x 102 kJ
4. It is determined that for a particular process, ΔH =
+185 J and ΔS = +1.80 J/K. At what temperature does
the reaction become spontaneous?
(a) 187 K
(b) 376 K
(c) 0.00973 K
(d) 103 K
(e) 333 K
5. The lowest possible entropy achievable occurs:
(a) when a liquid is converted to a solid
(b) only at very high temperatures
(c) only in the vapor phase
(d) at the completion of an endothermic reaction
(e) in a perfect crystal at 0 K
6. Which of the following statements are true for the
reaction I2(g) → 2 I(g) (Circle all that apply.)
(a) ΔH is positive
(b) ΔH is negative
(c) ΔS is positive
(d) ΔS is negative
(e) It’s spontaneous at any temperature
7. Which of the following statements is true?
(a) For a process to be spontaneous, the number of
moles of product must exceed the number of
moles of reactant
(b) The entropy of the universe is increasing
(c) A system at constant temperature cannot
experience entropy changes
(d) Exothermic reactions are always spontaneous
(e) In a spontaneous process, ΔG has a positive
value
Electrochem Practice Problems
1. What is the oxidation state of each element in
(a) H2? (b) Au(CN)4-? (c) XeOF4?
2. Which of the following reactions is NOT a redox
reaction?
(a) 2Na + Cl2 → 2NaCl
(b) C2H4 + 3O2 → 2CO2 + 2H2O
(c) Ni2+ + Fe → Fe2+ + Ni
(d) NaOH + HCl → NaCl + H2O
3. Which of the following terms best describes CH4 in
the following reaction? More than one choice may work.
CH4 + 2 O2 → CO2 + 2 H2O
(a) oxidized
(b) oxidizing agent
(c) reducing agent
(d) reduced
4. Which half-reaction takes place at the anode?
(a) the one with the greater reduction potential
(b) the one that transfers the highest number of
electrons
(c) the reduction
(d) the oxidation
5. Using your chemical intuition, determine which of the
following species is the strongest oxidizing agent: F2, H2,
Br2, or Ca? (HINT: Which one most “wants” to be
reduced?)
6. Which of the following is NOT produced during the
electrolysis of water?
(a) Electricity
(b) Acid
(c) Hydrogen
(d) Oxygen
7. According to your chemical intuition, what
combination of elements would make a very powerful
battery?
(a) F and Cl
(b) F and Li
(c) I and Fe
(d) Cd and Fe