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CHM-152 > Test 2 > Flashcards

Test 2 Flashcards

1
Q 
1. For the following reaction, ΔP(C6H14)/Δt was found to be –6.2 × 10–3 atm/s.
C6H14(g) --> C6H6(g) + 4H2(g)
Determine ΔP(H2)/Δt for this reaction at the same time.
A) 6.2 × 10–3 atm/s 
B) 1.6 × 10–3 atm/s 
C). 2.5 × 10–2 atm/s
D) –1.6 × 10–3 atm/s
E) –2.5 × 10–2 atm/s
A

C). 2.5 × 10–2 atm/s

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2
Q

For the overall chemical reaction shown below, which one of the following statements can be rightly assumed? 2H2S(g) + O2(g) –> 2S(s) + 2H2O(l)
A) The reaction is third-order overall.
B) The reaction is second-order overall.
C) The rate law is, rate = k[H2S]2 [O2].
D) The rate law is, rate = k[H2S] [O2].
E) The rate law cannot be determined from the information given.

A

E) The rate law cannot be determined from the information given

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3
Q 
Concerning the rate law, Rate = k[A] what are appropriate units for the rate constant k? 
A) s-1 
B) M-1s-1 
C) M-2s-1 
D) M/s 
E) M2/s
A

s-1

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4
Q

Which one of the following changes would alter the rate constant (k) for the reaction 2A + B –> products?
A) increasing the concentration of A
B) increasing the concentration of B
C) increasing the temperature
D) measuring k again after the reaction has run for a while

A

C) increasing the temperature

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5
Q 
The reaction C4H10 --> C2H6 + C2H4 has activation energy (Ea) of 450 kJ/mol, and the Ea of the reverse reaction is 250 kJ/mol. Estimate ΔH, in kJ/mol, for the reaction as written above.
A) –200 kJ/mol 
B) –700 kJ/mol 
C) +200 kJ/mol
D) +700 kJ/mol 
E) 450 kJ/mol
A

C) +200 kJ/mo

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6
Q

Complete the following statement: A catalyst
A) increases the activation energy.
B) alters the reaction mechanism.
C) increases the average kinetic energy of the reactants.
D) increases the concentration of reactants.
E) increases the collision frequency of reactant molecules.

A

B) alters the reaction mechanism.

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7
Q 
The reaction 2NO2(g) 2NO(g) ⇌ O2(g) is suspected to be second order in NO2. Which of the following kinetic plots would be the most useful to confirm whether or not the reaction is second order?
A) a plot of [NO2]–1 vs. t 
B) a plot of ln [NO2] vs. t 
C) a plot of [NO2] vs. t
D) a plot of ln [NO2]–1 vs. t
E) a plot of [NO2]2 vs. t
A

A) a plot of [NO2]–1 vs. t

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8
Q

When the concentrations of reactant molecules are increased, the rate of reaction increases. The best explanation for this phenomenon is that as the reactant concentration increases,
A) the average kinetic energy of molecules increases.
B) the frequency of molecular collisions increases.
C) the rate constant increases.
D) the activation energy increases.
E) the order of reaction increases.

A

B) the frequency of molecular collisions increases

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9
Q 
The half life for a first order reaction is 45 min. What is the rate constant in units of s-1?
A) 0.015 s^-1 
B) 65 s^-1 
C) 2.6 x 10-4 s^-1 
D) 3.9 x 103 s^-1 
E) 1.9 x 103 s^-1
A

C) 2.6 x 10-4 s^-1

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10
Q 
It takes 42.0 min for the concentration of a reactant in a first-order reaction to drop from 0.45 M to 0.32 M at 25°C. How long will it take for the reaction to be 90% complete?
A) 13.0 min 
B) 86.0 min 
C) 137 min 
D) 222 min 
E) 284 min
A

E) 284 min

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11
Q 
The equilibrium constant for the reaction Ni(s) ⇌ 4CO(g) Ni(CO)4(g) is 5.0 × 104 at 25ºC. What is the equilibrium constant for the reaction
Ni(CO)4(g) Ni(s) ⇌ 4CO(g)?
A) 2.0 × 10^–5 
B) 2.5 × 10^9 
C) 5.0 × 10^4 
D) 5.0 × 10^–4 
E) 2.0 × 10^–3
A

A) 2.0 × 10^–5

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12
Q 
Which is the correct equilibrium constant expression for the following reaction?
Fe2O3 (s) + 3H2 (g) ⇌ 2Fe (s) + 3H2O (g)
A) Kc = [Fe2O3] [H2]^3 / [Fe]2[H2O]^3 
B) Kc = [H2] / [H2O] 
C) Kc = [H2O]^3 / [H2]^3
D) Kc = [Fe]2[H2O]^3 / [Fe2O3] [H2]^3
E) Kc = [Fe] [H2O] / [Fe2O3] [H2]
A

C) Kc = [H2O]^3 / [H2]^3

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13
Q

At 700 K, the reaction 2SO2(g) + O2(g) ⇌ 2SO3(g) has the equilibrium constant Kc = 4.3 × 106, and the following concentrations are present: [SO2] = 0.010 M; [SO3] = 10. M; [O2] = 0.010 M. Which of the following is true based on the above?
A) Qc > Kc, the reaction proceeds from left to right to reach equilibrium
B) Qc > Kc, the reaction proceeds from right to left to reach equilibrium
C) Qc < Kc, the reaction proceeds from left to right to reach equilibrium
D) Qc < Kc, the reaction proceeds from right to left to reach equilibrium
E) Qc = Kc, the reaction is currently at equilibrium

A

B) Qc > Kc, the reaction proceeds from right to left to reach equilibrium

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14
Q

For the following reaction at equilibrium, which gives a change that will shift the position of equilibrium to favor formation of more products?
2NOBr(g) ⇌ 2NO(g) + Br2(g), ΔHºrxn = 30 kJ/mol
A) Increase the total pressure by decreasing the volume.
B) Add more NO.
C) Remove Br2.
D) Remove NOBr selectively
E) Lower the temperature.

A

C) Remove Br2.

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15
Q

Which of these situations will result if some H2(g) is removed from the reaction
CO(g) + 3H2(g) ⇌ CH4(g) + H2O(g) at equilibrium?
A) H2O will be consumed.
B) More CH4 and H2O will be produced.
C) Kp will decrease.
D) More CO will be consumed.
E) No change will occur.

A

A) H2O will be consumed.

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16
Q 
Calculate Kc for the reaction 2HI(g) ⇌ H2(g) + I2(g) given that the concentrations of each species at equilibrium are as follows: [HI] = 0.85 mol/L, [I2] = 0.60 mol/L, [H2] = 0.27 mol/L.
A) 5.25 
B) 0.22 
C) 4.5 
D) 0.19 
E) 1.6 × 10^2
A

B) 0.22

17
Q 
Kp for the reaction CO2(g) + C(s) ⇌ 2CO(g) is 1.47 at 727°C. Calculate Kc at this temperature
A) 1.47 
B) 121 
C) 0.0246 
D) 0.0179 
E) 87.7
A

D) 0.0179

18
Q 
Given the following data for the reaction: A(g) + 2B(s) ⇌ AB2(g):
Temp (K) / Kc
300 / 1.5 x 10^4
600 / 55
900 / 3.4 x 10^-3
This reaction is;
A) Endothermic 
B) Exothermic 
C) not enough information
A

B) Exothermic

19
Q

Concerning the following reaction at equilibrium:
3Fe(s) + 4H2O(g) ⇌ Fe3O4(s) + 4H2(g),
increasing the concentration of the Fe(s) would:
A) Shift the equilibrium to the right
B) Shift the equilibrium to the left
C) Increase the value of the equilibrium constant, K
D) Decrease the value of the equilibrium constant, K
E) No change

A

E) No change

20
Q

Sodium carbonate, Na2CO3(s), can be prepared by heating sodium bicarbonate, NaHCO3(s) as shown below.
2NaHCO3(s) ⇌ Na2CO3(s) + CO2(g) + H2O(g)
Kp = 0.23 at 100ºC
If a sample of NaHCO3 is placed in an evacuated flask and allowed to achieve equilibrium at 100ºC, what will the total gas pressure be?
A) 0.46 atm
B) 0.96 atm
C) 0.23 atm
D) 0.48 atm
E) 0.11 atm

A

B) 0.96 atm

21
Q 
In which of these gas-phase equilibria is the yield of products increased by increasing the total pressure on the reaction mixture?
A) CO(g) + H2O(g) ⇌ CO2(g) + H2(g) 
B) 2NO(g) + Cl2(g) ⇌ 2NOCl(g) 
C) 2SO3(g) ⇌ 2SO2(g) + O2(g)
D) PCl5(g) ⇌ PCl3(g) + Cl2(g)
E) H2(g) + I2(g) ⇌ 2HI(g)
A

B) 2NO(g) + Cl2(g) ⇌ 2NOCl(g)

22
Q

For the nitrogen fixation reaction 3H2(g) + N2(g) ⇌ 2NH3(g), Kc = 6.0 × 10^–2 at 500°C.
If 0.250 M H2 and 0.050 M NH3 are present at equilibrium, what is the equilibrium concentration of N2?
A) 0.750 M
B) 2.7 M
C) 0.250 M
D) 0.025 M
E) 1.85 M

A

B) 2.7 M

23
Q 
Which of the following does not fit the definition of a Brønsted Acid?
A) H3PO4 
B) H2PO4– 
C) H2O 
D) NH4+ 
E) CO2
A

E) CO2

24
Q 
Identify the conjugate base of HPO42–
A) H2O 
B) H2PO4– 
C) H3PO4 
D) PO43– 
E) OH–
A

D) PO43–

25
Q 
Identify the conjugate acid of HCO3–
A) H2O 
B) CO32– 
C) H2CO3 
D) CO2 
E) H3O+
A

E) H3O+

26
Q 
The OH– concentration in a 1.0 × 10^–3 M Ba(OH)2 solution is
A) 0.50 × 10^–3 M
B) 1.0 × 10^–3 M 
C) 2.0 × 10^–3 M
D) 1.0 × 10^–2 M
E) 0.020 M
A

C) 2.0 × 10^–3 M

27
Q 
What is the H+ ion concentration in a 4.8 × 10–2 M KOH solution?
A) 4.8 × 10^–2 M
B) 1.0 × 10^–7 M 
C) 4.8 × 10^–11 M
D) 4.8 × 10^–12 M 
E) 2.1 × 10^–13 M
A

E) 2.1 × 10^–13 M

28
Q 
A 0.10 M HF solution is 8.4% ionized. Calculate the H+ ion concentration.
A) 0.84 M 
B) 0.12 M 
C) 0.10 M 
D) 0.084 M 
E) 8.4 × 10^–3 M
A

E) 8.4 × 10^–3 M

29
Q 
Calculate the pH of a 6.7 × 10–2 M NaOH solution.
A) 12.83 
B) 2.17 
C) 11.82 
D) 6.71 
E) 1.17
A

A) 12.83

30
Q 
The pOH of a solution is 9.60. Calculate the hydrogen ion concentration in this solution.
A) 2.5 × 10^–10 M
B) 6.0 × 10^–9 M 
C) 4.0 × 10^–5 M
D) 2.4 × 10^–4 M
E) 1.0 × 10^–14 M
A

C) 4.0 × 10^–5 M

31
Q 
31. Arrange the acids HOBr, HBrO3, and HBrO2 in order of increasing acid strength.
A) HOBr < HBrO3 < HBrO2 
B) HOBr < HBrO2 < HBrO3 
C) HBrO2 < HOBr < HBrO3
D) HBrO3 < HOBr < HBrO2
E) HBrO3 < HBrO2 < HOBr
A

B) HOBr < HBrO2 < HBrO3

32
Q 
Arrange the acids H2Se, H2Te, and H2S in order of increasing acid strength.
A) H2S < H2Se < H2Te 
B) H2S < H2Te < H2Se 
C) H2Te < H2S < H2Se
D) H2Se < H2S < H2Te
E) H2Se < H2Te < H2S
A

A) H2S < H2Se < H2Te

33
Q 
Which of these species will act as a Lewis acid?
A) NH3 
B) NH4+ 
C) H2O 
D) BF3 
E) F–
A

D) BF3

CHM-152 (3 decks)

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