Test tasks

 

 

1. At equilibrium, …
A. the rates of the forward and reverse reactions are equal
B. the rate constants of the forward and reverse reactions are equal
C. all chemical reactions have ceased
D. the value of the equilibrium constant is 1
E. the limiting reagent has been consumed
2. The value of Keq for the following reaction is 0.25:
SO2 (g) + NO2 (g) ↔ SO3 (g) + NO (g)
The value of Keq at the same temperature for the reaction below is …
2SO2 (g) + 2NO2 (g) ↔ 2SO3 (g) + 2NO (g)
A. 0.062
B. 16
C. 0.25
D. 0.50
E. 0.12
3. How is the reaction quotient used to determine whether a system is at equilibrium?
A. The reaction is at equilibrium when Q < Keq.
B. The reaction is at equilibrium when Q > Keq.
C. At equilibrium, the reaction quotient is undefined.
D. The reaction quotient must be satisfied for equilibrium to be achieved.
E. The reaction is at equilibrium when Q = Keq.
4. Consider the following reaction at equilibrium:
2CO2 (g) ↔ 2CO (g) + O2 (g) ∆Hº = -514 kJ
Le Chatelier's principle predicts that adding O2 (g) to the reaction container will …
A. decrease the partial pressure of CO2 (g) at equilibrium
B. decrease the value of the equilibrium constant
C. increase the partial pressure of CO2 (g) at equilibrium
D. increase the value of the equilibrium constant
E. increase the partial pressure of CO (g) at equilibrium
5. Phosphorous trichloride and phosphorous pentachloride equilibrate in the presence of molecular chlorine according to the reaction:
PCl3 (g) + Cl2 (g) → PCl5 (g)
Keq = 2.01 at 500 K. A 1.000-L reaction vessel is charged with 0.300 mol of PCl5 and allowed to equilibrate at this temperature. The equilibrium partial pressure of PCl5 is … atm.
A. 0.386
B. 2.24
C. 2.48
D. 10.1
E. 0.211
6. Which one of the following will change the value of an equilibrium constant?
A. adding other substances that do not react with any of the species involved in the equilibrium
B. varying the initial concentrations of reactants
C. changing temperature
D. varying the initial concentrations of products
E. changing the volume of the reaction vessel
7. At 200ºC, the equilibrium constant for the reaction below is 2.40 × 103.
2NO (g) ↔ N2 (g) + O2 (g)
A closed vessel is charged with 36.1 atm of NO. At equilibrium, the partial pressure of O2 is … atm.
A. 35.7
B. 18.1
C. 1.50 × 10-2
D. 6.00
E. 294
8. In which of the following reactions would increasing pressure at constant temperature not change the concentrations of reactants and products, based on Le Chatelier's principle?
A. N2 (g) + 3H2 (g) ↔ 2NH3 (g)
B. 2N2 (g) + O2 (g) ↔ 2N2O (g)
C. N2 (g) + 2O2 (g) ↔ 2NO2 (g)
D. N2O4 (g) ↔ 2NO2 (g)
E. N2 (g) + O2 (g) ↔ 2NO (g)
9. The effect of a catalyst on an equilibrium is to …
A. increase the rate at which equilibrium is achieved without changing the composition of the equilibrium mixture
B. increase the rate of the forward reaction only
C. shift the equilibrium to the right
D. increase the equilibrium constant so that products are favored
E. slow the reverse reaction only
10. The unit of the rate of reaction is:
A. mol -1 L min-1
B. mol L-1 min -1
C. both a and b
D. none of these
11. The rate of reaction depends upon the molar concentration of reactants which:
A. Keep on increasing with passage of time.
B. Keep on decreasing with passage of time.
C. Remains same with passage of time.
D. Does not depend upon the time.
12. The factors on which the rate of reaction depends is:
A. Temperature.
B. Presence of catalyst.
C. Presence of light.
D. All of these.
13. The three-fourth of a first order reaction is completed in 32 minutes. Find the half-life period of the reaction?
A. 70 min.
B. 30 min
C. 16 min.
D. 96 min
14. What is the order of reaction, if the rate constant of a reaction is 1.2 x 10-2 mol-2
A. 2
B. 0
C. 1
D. 3
15. What percentage of the reactant will be left behind after 120 minutes, if the half-life period of a first order reaction is 60 minutes?
A. 25%
B. 20%
C. 30%
D. 40%
16. The reaction H+ + OH- ? H2O is:
A. Slow
B. Very slow
C. Fast
D. Moderate in speed
17. … is used for studying the rate of a reaction.
A. Chemical equilibrium
B. Chemical mechanism
C. Chemical thermodynamics
D. Chemical kinetics.
18. The rate of a reaction doubles when the temperature changes from 27°C to 37°C. Calculate the energy of activation.
A. 54.6 kJ mol-1
B. 53.6 kJ mol-1
D. 52.6 kJ mol-1
E. 54.1 kJ mol-1
19. Which among the following is not an example of second order reaction?
A. Dissociation of HI.
B. Dissociation of COCl2
C. Saponification of ethyl acetate.
D. Reaction between NO and O3.
20. The rate constant of a reaction is 1.2 x 10-3 sec-1 at 30°C and 2.1 x 10-3 sec-1 at 40°C. Calculate the energy of activation of the reaction.
A. 67.32 kJ mol-1
B. 98.76 kJ mol-1
C. 44.13 kJ mol-1
D. 12.45 kJ mol-1