1. It is a condition that occurs when opposing reactions are proceeding at equal rates.
a. Chemical kinetics
b. Chemical equilibrium
c. Chemical reaction
d. Chemical equation
2. Which of the following is not included when writing equilibrium constant expression?
a. gases
b. aqueous solutions
c. liquids
d. pure liquids and solids
3. Equilibrium constant greater than 1 means
a. equilibrium constant lies to the right , products predominate.
b. equilibrium constant lies to the left, reactants predominate.
c. equilibrium constant lies to the right, reactants predominate.
d. equilibrium constant lies to the left, products predominate.
4. What does it mean when the Keq < 1?
a. Equilibrium constant lies to the right , products predominate.
b. Equilibrium constant lies to the left, reactants predominate.
c. Equilibrium constant lies to the right, reactants predominate.
d. Equilibrium constant lies to the left, products predominate.
5. What is the equilibrium constant expression of aA + bB ⇌ cC + dD?
6. Which of the following is not a factor that affects chemical equilibrium?
a. concentration
b. temperature
c. pressure and volume
d. density
7. Equilibria in which all substances are in the same phases are called
a. homogeneous equilibria.
b. heterogeneous equilibria.
c. equilibrium constant
d. equilibrium constant expression.
8. Equilibria in which two or more phases are present in the reaction are called
a. homogeneous equilibria.
b. heterogeneous equilibria.
c. equilibrium constant
d. equilibrium constant expression.
9. A principle which states that if a system at equilibrium is disturbed, the equilibrium will shift to minimize the disturbing influence.
a. Uncertainty Principle
b. Principle of Mass Action
c. Le Chatelier's Principle
d. Chatelier's Principle
10. What is the Keq expression of the equation below?
N2(g) + 3H2(g) ⇌ 2NH3(g)
11. How does increase of concentration of the reactants affects equilibrium?
a. Equilibrium will shift to the left forming more products.
b. Equilibrium will shift to the right forming more reactants.
c. Equilibrium will shift to the left forming more reactants.
d. Equilibrium will shift to the right forming more products.
12. Where is the direction of equilibrium upon removal of NH3 in the reaction below:
N2(g) + 3H2(g) ⇌ 2NH3(g)
a. Equilibrium will shift to the right producing more NH3.
b. Equilibrium will shift to the left, producing more N2 and H2.
c. Equilibrium will increase in favor of the products.
d. Equilibrium will remain the same.
13. Which reaction below is exothermic?
a. Reactant + heat ⇌ products
b. Reactants ⇌ products
c. Reactants + heat ⇌ products + heat
d. Reactants ⇌ products + heat
14. Which reaction below is endothermic?
a. PCl5(g) ⇌ PCl3(g) + Cl2(g), ∆H = 87.9 kJ
b. N2(g) ⇌ 3H2(g) + 2NH3(g), ∆H = -92.38 kJ
c. 2PCl3(g) + O2(g) ⇌ 2POCl3(g), ∆H = -508 kJ
d. 2NO2(g) ⇌ N2O4(g), ∆H = -58.0 kJ
15. Which of the following equations is an example of heterogeneous equilibrium?
a. 3NO(g) ⇌ N2O(g) + NO2(g)
b. HF(aq) ⇌ H+(aq) + F-(aq)
c. CH4(g) + 2H2S(g) ⇌ CS2(g) + 4H2(g)
d. 2Ag(s) + Zn+2(aq) ⇌ 2Ag+2(aq) + Zn(s)
16. What does [ ] mean in Keq expression?
a. molarity
b. concentration
c. volume
d. pressure
17. Consider the equilibrium, N2O4(g) ⇌ 2NO2(g),
What will happen if the total pressure is increased by decreasing the volume?
a. Equilibrium will shift to the right, in favor of more number of moles of gas.
b. Equilibrium will shift to the left, in favor of less number of moles of gas.
c. Equilibrium will shift to both directions.
d. No shift will occur.
18. How is equilibrium constant expression written?
a. By dividing the concentration of the products raised to a certain power by the concentration of the reactant raised to a certain power.
b. By dividing the concentration of the reactants raised to a certain power by the concentration of the products raised to a certain power.
c. By multiplying the concentration of the products and the concentration of the reactants.
d. By adding the concentration of the products to the concentration of the reactants.
19. In writing chemical equilibrium expression, the concentrations of the reactants and products are raised to a certain power equal to
a. subscript of the reactants and products.
b. coefficient of the reactants and products.
c. volume of the reactants and products.
d. pressure of the reactants and products.
20. Keq values of forward and reverse reactions are reciprocal of one another. The Keq at 100oC of
2NOBr(g) ⇌ 2NO(g) + Br2(g) is 0.42. What is the Keq of 2NO(g) + Br2(g) ⇌ 2NOBr(g) at the same temperature?
a. 0.176
b. 1.76
c. 2.4
d. 4.2
21. Based from the chemical equilibrium in number 20, what is the Keq of
4NOBr(g) ⇌ 4NO(g) + 2Br2(g)?
a. 0.176
b. 0.84
c. 1.76
d. 8.4
22. Which is true about equilibrium constant expression?
a. An algebraic equation where the variables are the equilibrium concentration of the reactants and products.
b. Is a number, it is a ratio calculated from the equilibrium expression for a particular reaction.
c. Is dependent on the mechanism of the reaction.
d. Is a ratio of the concentration of the reactants and products.
23. What is the function of catalyst in chemical equilibrium?
a. It changes the composition of equilibrium mixture.
b. It increases the rate at which equilibrium is achieved.
c. It changes the value of the equilibrium constant for a reaction.
d. It increases the activation barrier between reactants and products.
24. Which of the following reactions contains most of the products?
a. N2(g) + O2(g) ⇌ 2NO(g) ; Keq = 1.5 x 10-10
b. 2SO2(g) + O2(g) ⇌ 2SO3(g) ; Keq = 2.5 x 109
c. 2NO(g) + O2(g) ⇌ 2NO2(g) ; Keq = 5.0 x 1012
d. 2HBr(g) + H2(g) ⇌ H2(g) + Br2(g) ; Keq = 5.8 x 10-18
25. Which of the reaction in number 24 contains the most of the reactants?
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