PRACTICE EXAM SOLUTION MID TERM II, CHEMISTRY 162
Useful equations: pH = pKA + log ([A-]/[HA]) Kp = Kc(RT)Δn Kw = 1 x 10-14
1.) The following reaction is known as the Haber process which is responsible for nearly 80% of the nitrogen
found in human tissues, which set of conditions would give more product?
N2 (g) + 3 H2 (g) 2 NH3 (g) ΔH = –46.19 kJ
A) High pressure and high temperature
B) Low pressure and low temperature
C) Low pressure and high temperature
D) High pressure and low temperature
2.) Write the formula for the conjugate base for HCHO2.
A) CHO2 -
B) CO2-
C) HCHO2
D) H2CHO2 +
E) none of these
3.) Give the direction of the reaction, if K << 1.
A) The forward reaction is favored.
B) The reverse reaction is favored.
C) Neither direction is favored.
D) If the temperature is raised, then the forward reaction is favored.
E) If the temperature is raised, then the reverse reaction is favored.
4.) A 100.0 mL sample of 0.10 M NH3 is titrated with 0.10 M HNO3. Determine the pH of the solution after the
addition of 200.0 mL of HNO3. The Kb of NH3 is 1.8 × 10-5.
A) 6.74
B) 1.48
C) 3.00
D) 12.52
E) 5.70
5.) Calculate the molar solubility of magnesium iodide in water from its Ksp at 25 °C. (Ksp = 7.9 x 10-
9)a) 7.90 x 10-9 b) 2.01 x 10-9 c) 1.25 x 10-3 d) 5.31 x 10-3 e) 1.25 x 103
MgI2(s) Mg2+(aq) + 2I-(aq) Ksp = [Mg2+][I-]2 = 7.9 x 10 -9
The solvent is water, so the initial concentrations of the ions are zero. Thus, the coefficients of x in
the “change” row will be identical to the coefficients of the ions in the chemical equation. This assures
us thatthe changes in the concentrations are in the correct mole ratio.
MgI2(s) Mg2+(aq) + 2I-(aq)
Initial concentrations (M) - 0 0
Changes in concentrations when PbI2 dissolves - + +2
(M)Equilibrium concentrations (M) - xx x
2x
Ksp = (x)(2x)2 =4x3 = 7.9 x 10-9
x3 = 1.975 x 10-9
, x = 1.2546 x 10-3
Useful equations: pH = pKA + log ([A-]/[HA]) Kp = Kc(RT)Δn Kw = 1 x 10-14
1.) The following reaction is known as the Haber process which is responsible for nearly 80% of the nitrogen
found in human tissues, which set of conditions would give more product?
N2 (g) + 3 H2 (g) 2 NH3 (g) ΔH = –46.19 kJ
A) High pressure and high temperature
B) Low pressure and low temperature
C) Low pressure and high temperature
D) High pressure and low temperature
2.) Write the formula for the conjugate base for HCHO2.
A) CHO2 -
B) CO2-
C) HCHO2
D) H2CHO2 +
E) none of these
3.) Give the direction of the reaction, if K << 1.
A) The forward reaction is favored.
B) The reverse reaction is favored.
C) Neither direction is favored.
D) If the temperature is raised, then the forward reaction is favored.
E) If the temperature is raised, then the reverse reaction is favored.
4.) A 100.0 mL sample of 0.10 M NH3 is titrated with 0.10 M HNO3. Determine the pH of the solution after the
addition of 200.0 mL of HNO3. The Kb of NH3 is 1.8 × 10-5.
A) 6.74
B) 1.48
C) 3.00
D) 12.52
E) 5.70
5.) Calculate the molar solubility of magnesium iodide in water from its Ksp at 25 °C. (Ksp = 7.9 x 10-
9)a) 7.90 x 10-9 b) 2.01 x 10-9 c) 1.25 x 10-3 d) 5.31 x 10-3 e) 1.25 x 103
MgI2(s) Mg2+(aq) + 2I-(aq) Ksp = [Mg2+][I-]2 = 7.9 x 10 -9
The solvent is water, so the initial concentrations of the ions are zero. Thus, the coefficients of x in
the “change” row will be identical to the coefficients of the ions in the chemical equation. This assures
us thatthe changes in the concentrations are in the correct mole ratio.
MgI2(s) Mg2+(aq) + 2I-(aq)
Initial concentrations (M) - 0 0
Changes in concentrations when PbI2 dissolves - + +2
(M)Equilibrium concentrations (M) - xx x
2x
Ksp = (x)(2x)2 =4x3 = 7.9 x 10-9
x3 = 1.975 x 10-9
, x = 1.2546 x 10-3
