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Practice MC Questions-S22 112 Final Exam Review
CHEM 112
Practice Questions for Final Exam
- Which one of the following substances has dispersion forces as its only intermolecular force?
(A) CH 3 OH (B) NH 3 (C) H 2 S (D) Br 2
- Which of the following properties indicates the presence of strong intermolecular forces in a liquid?
(A) a low heat of vaporization (B) a low vapor pressure
(C) a low boiling point (D) a low melting point
- Which of the following molecules will have the highest boiling point, H 2 , N 2 , F 2 or Cl 2?
(A) H 2 (B) N 2 (C) F 2 (D) Cl (^2)
- How much energy is required to heat 42.0 g of C 6 H 6 ( l ) from 20.0 °C to 45.2 °C? The molar mass of benzene is 78.11 g/mol.
Normal boiling point 80.09 °C Specific heat 1.63 J/g • °C Molar heat of vaporization 30.72 kJ/mol
(A) 3.09 × 10^3 J (B) 1.73 × 10^3 J (C) 1.65 × 10^4 J (D) 5.48 × 10^3 J
- Liquid ammonia can be used as a refrigerant and heat transfer fluid. How much energy is required to
heat 25.0 g of NH 3 ( l ) from – 65.0°C and convert it to NH 3 ( g ) at its boiling point??
Normal boiling point – 33.4°C Specific heat of NH 3 ( l ) 4.7 J/g • °C Specific heat of NH 3 ( g ) 2.2 J/g • °C Molar mass of NH 3 17.03 g mol−^1 Molar heat of vaporization 23.5 kJ/mol Molar heat of fusion 5.653 kJ/mol
(A) 3.71 kJ (B) 34.5 kJ (C) 38.2 kJ (D) 59.1 kJ
- Based on the phase diagram of a pure substance given below, what phase change occurs as the substance changes from point C to point D?
(A) sublimation (B) melting (C) condensation (D) freezing
C
D
Practice MC Questions-S22 112 Final Exam Review
- Consider this reaction: P 4 ( s ) + 6Cl 2 ( g ) 4 PCl 3 ( g ).
What is the correct K c expression for this reaction?
(A)
[ ]
c 6 2
Cl
K = (B)
[ ][ ]
4 3 c 6 4 2
[PCl ] P Cl
K =
(C)
[ ]
4 3 c (^6) 2
[PCl ] Cl
K = (D)
[ ][ ]
6 4 2 c (^4) 3
P Cl [PCl ]
K =
- Calculate K c for the reaction 2 HI( g ) ⇌ H 2 ( g ) + I 2 ( g ) given that the concentrations of each species at equilibrium are as follows: [HI] = 0.85 mol/L, [I 2 ] = 0.60 mol/L, [H 2 ] = 0.27 mol/L.
(A) 5.25 (B) 0.
(C) 4.5 (D) 0.
- The equilibrium constant K c for the reaction
PCl 3 ( g ) + Cl 2 ( g ) ⇌ PCl 5 ( g ) is 49 at 230°C. If 0.70 mol of PCl 3 is added to 0.70 mol of Cl 2 in a 1.00-L reaction vessel at 230°C, what is the concentration of PCl 3 when equilibrium has been established?
(A) 0.049 M (B) 0.11 M
(C) 0.30 M (D) 0.59 M
- For which of the following reactions is K (^) c equal to K (^) p?
(A) N 2 O 4 ( g ) ⇌ 2 NO 2 ( g ) (B) N 2 ( g ) + O 2 ( g ) ⇌ 2 NO( g )
(C) CaCO 3 ( s ) ⇌ CaO( s ) + CO 2 ( g ) (D) PCl 3 ( g ) + Cl 2 ( g ) ⇌ PCl 5 ( g )
- Carbon tetrachloride reacts at high temperatures with oxygen to produce two toxic gases, phosgene and chlorine. CCl 4 ( g ) + ½ O 2 ( g ) ⇌ COCl 2 ( g ) + Cl 2 ( g ), Kc What is the equilibrium constant for the reaction 2 CCl 4 ( g ) + O 2 ( g ) ⇌ 2 COCl 2 ( g ) + 2 Cl 2 ( g ) Kc ′?
(A) (^) c^1 c
K^ ′ = (^) K (B) K (^) c ′ = 2 Kc
(C) K (^) c ′ = Kc^2 (D) K (^) c ′ =^12 Kc
Practice MC Questions-S22 112 Final Exam Review
- For the reaction PCl 3 ( g ) + Cl 2 ( g ) ⇌ PCl 5 ( g ) at a particular temperature, K c = 32.4. Suppose a system at that temperature is prepared with [PCl 5 ] = 0.50 M , [Cl 2 ] = 0.40 M , and [PCl 3 ] = 0.10 M. Which of the following statements is correct?
(A) Qc < K (^) c ; The reaction will proceed in the direction of forming more PCl 5 until equilibrium is reached.
(B) Qc > K (^) c ; The reaction will proceed in the direction of forming more PCl 3 and Cl 2 until equilibrium is reached.
(C) Qc < K (^) c ; The reaction will proceed in the direction of forming more PCl 3 and Cl 2 until equilibrium is reached.
(D) Qc > K (^) c ; The reaction will proceed in the direction of forming more PCl 5 until equilibrium is reached.
- A container was charged with hydrogen, nitrogen, and ammonia gases at 120°C and the system was allowed to reach equilibrium. What will happen if the volume of the container is increased at constant temperature? 3 H 2 ( g ) + N 2 ( g ) ⇌ 2 NH 3 ( g )
(A) There will be no effect.
(B) More ammonia will be produced at the expense of hydrogen and nitrogen.
(C) Hydrogen and nitrogen will be produced at the expense of ammonia.
(D) The equilibrium constant will decrease.
- The following reaction is at equilibrium in a sealed container.
N 2 ( g ) + 3H 2 ( g ) ⇌ 2NH 3 ( g ); ∆ H °rxn < 0 Which, if any, of the following actions will increase the value of the equilibrium constant, K (^) c?
(A) adding a catalyst. (B) adding more N 2.
(C) increasing the pressure. (D) lowering the temperature.
- In which of these equilibria is the yield of reactants increased by increasing the total pressure on the
reaction mixture?
(A) CO( g ) + Cl 2 ( g ) ⇌ COCl 2 ( g )
(B) H 2 ( g ) + CO 2 ( g ) ⇌ H 2 O( g ) + CO( g )
(C) 2 CO( g ) ⇌ C( s ) + CO 2 ( g )
(D) 2 SO 3 ( g ) ⇌ 2 SO 2 ( g ) + O 2 ( g )
- For the reaction, 2 H 2 O 2 ( g ) ∏ 2 H 2 O( g ) + O 2 ( g ), ∆ Hº rxn = −210 kJ/mol. Which of the following statements is correct?
(A) K p at 800 K is smaller than K p at 1200 K.
(B) The partial pressure of H 2 O 2 is less at 800 K than at 1200 K.
(C) Higher total pressure shifts the equilibrium to the right.
(D) The value of K p is equal to the value of K C.
Practice MC Questions-S22 112 Final Exam Review
- A 0.15 M solution of chloroacetic acid has a pH of 1.86. What is the value of K a for this acid?
(A) 7.2 × 101 (B) 0.
(C) 0.099 (D) 0.
- A 1.25 M solution of the weak acid HA is 9.2% dissociated. What is the pH of the solution?
(A) 0.64 (B) 0.
(C) 1.13 (D) 2.
- Four weak acids have the formulas and K (^) a values listed:
Acid Molecular Formula (^) Ka at 25 °C Acetic acid CH 3 COOH (^) 1.8 × 10 −^5 Formic acid HCOOH 1.7 × 10 −^4 Cyanic acid HOCN (^) 3.5 × 10 −^4 Hydrofluoric acid HF (^) 7.1 × 10 −^4
Which of the following solutions will have the highest percent ionization?
(A) 1 M CH 3 COOH (B) 1 M HCOOH
(C) 1 M HOCN (D) 1 M HF
42. Oxalic acid, H 2 C 2 O4, is a weak diprotic acid. In a 0.10 M solution of oxalic acid, which species would
have the lowest concentration?
(A) H 2 C 2 O 4 (B) HC 2 O 4 −
(C) H 3 O+^ (D) C 2 O 42 −
- A solution is prepared by adding 0.10 mol of potassium chloride, KCl, to 1.00 L of water. Which statement about the solution is correct?
(A) The solution is basic. (B) The solution is neutral.
(C) The solution is acidic. (D) The values for K a and K b for the species in solution must be known before a prediction can be made.
- Which one of these salts will form an acidic solution upon dissolving in water?
(A) LiBr (B) NaF
(C) NH 4 Br (D) KOH
- Which of these species is a Lewis acid, but not a Brønsted acid?
(A) HCN (B) CO 3 2–
(C) Al 3+^ (D) NH 3
Practice MC Questions-S22 112 Final Exam Review
- If 100 mL of each of the following solutions is mixed, which one produces a buffer?
(A) 1.0 M HNO 3 ( aq ) + 1.0 M NaNO 3 ( aq )
(B) 1.0 M NH3 ( aq ) + 1.0 M NH 4 Cl ( aq )
(C) 1.0 M CH3COOH ( aq ) + 1.0 M NaOH ( aq )
(D) 1.0 M HCl ( aq ) + 1.0 M NaOH ( aq )
- Calculate the pH of a solution that is 0.41 M in HOCl and 0.050 M in NaOCl. The K a for HOCl is 3.2 × 10 –^.
(A) 7.49 (B) 6.
(C) 8.40 (D) 3.
- You have 500.0 mL of a buffer solution containing 0.20 M CH 3 COOH and 0.30 M NaCH 3 COO. What will be the pH of the solution after the addition of 20.0 mL of 1.00 M NaOH? The K a for CH 3 COOH is 1.8× 10 –^.
(A) 4.51 (B) 5.
(C) 4.77 (D) 4.
49. Which of the following is an approximate value of the pH at the equivalence point of a titration of a strong acid with a weak base?
(A) 0.0 (B) 8.
(C) 7.0 (D) 5.
50. Which titration will have an equivalence point with a basic pH?
(A) NH 3 + HCl (B) HNO 3 + Ca(OH) 2
(C) HNO 2 + NaOH (D) NaOH + HCl
- Calculate the solubility of silver oxalate, Ag 2 C 2 O 4 , in pure water. K sp = 1.0 × 10 –
(A) 1.4 × 10 –4^ M (B) 8.2 × 10 –5^ M
(C) 5.4 × 10 –5^ M (D) 3.2 × 10 –6^ M
- In which of the following solutions is PbI 2 least soluble?
(A) pure water (B) 0.2 M HI
(C) 0.1 M HNO 3 (D) 0.8 M KI
- Select the compound in which sulfur has its highest possible oxidation number.
(A) H 2 S (B) SO 2
(C) Na 2 SO 4 (D) SCl 2
Practice MC Questions-S22 112 Final Exam Review
- Consider the following oxidation-reduction reaction that takes place in a Galvanic cell:
2 MnO 4 −( aq ) + 3 Cu( s ) + 4 H 2 O( l ) + → 2 MnO 2 ( s ) + 3 Cu2+^ ( aq ) +8 OH−( aq )
which one of the following changes will cause a decrease in the cell voltage according to the Nernst equation?
(A) increase the pH
(B) increase the size/mass of the copper electrode
(C) increase the MnO 4 −^ concentration.
(D) decrease the Cu2+^ concentration.
- A metal object is to be gold-plated by an electrolytic procedure using aqueous AuCl 3 electrolyte. What is the mass of gold deposited in 3.0 min by a constant current of 10. A?
(A) 1.2 g (B) 3.7 g
(C) 10.9 g (D) 0.020 g
- Given the following data for this reaction: NH 4 +^ (aq) + NO 2 −( aq ) → N 2 ( g ) + 2H 2 O( l )
Experiment [NH 4 +^ ] ( M ) (^) [NO 2 −] (M) Initial Rate (M/s) 1 0.010 0.020 0. 2 0.015 0.020 0. 3 0.010 0.010 0.
The rate law for the reaction is:
(A) Rate = k [NH 4 +^ ][NO 2 −] (B) Rate = k [NH 4 +^ ]^2 [NO 2 −]^2
(C) Rate = k [NH 4 +^ ]^2 [NO 2 −] (D) Rate = k [NH 4 +^ ][NO 2 −]^2
- The half-life for the first order conversion of cyclobutene to ethylene is 22.7 s at a particular temperature. If the initial partial pressure of cyclobutene is 122 mmHg, what is the partial pressure of cyclobutene after 55.6 s?
(A) 131 mmHg (B) 22.2 mmHg (C) 12.2 mmHg ( (D) 10.5 mmHg
- Butadiene, C 4 H 6 (used to make synthetic rubber and latex paints) dimerizes to C 8 H 12 with a rate law of rate = 0.014 L/(mol • s) [C 4 H 6 ]^2. What will be the concentration of C 4 H 6 after 3.0 hours if the initial concentration is 0.025 M?
(A) 0.0052 M (B) 0.024 M (C) 0.43 M (D) 190 M
Molar Mass Au (^) 197.0 g mol−^1
