Chapter 15 Practice Test

Question 1

For a reaction A+B -> AB, the value of the equilibrium constant is less than 1. Therefore, which of the following statements is correct?

Answer 1

Equilibrium lies toward the formation of the reactants

Question 2

x moles of hydrogen are added to y moles of iodine, and z moles of hydrogen iodide are formed. What is the value of the equilibrium constant?

Answer 2

z^ 2 / [(x − z/2) (y − z/2)]

Question 3

A reaction reaches equilibrium in four hours. The equilibrium constant for this reaction is K1. A catalyst is added to this reaction, the reaction rate increases, and equilibrium is reached in one minute. The equilibrium constant for this reaction is K2. How are K1 and K2 related?

Answer 3

K1 = K2

Question 4

When sulfur dioxide is passed over calcium oxide, it combines with CaO to form CaSO3. This is one of the ways sulfur dioxide can be removed from a gas mixture. The reaction taking place is as follows:
CaO(s) + SO2(g) <==> CaSO3(s)
Which of the following expressions defines the equilibrium constant for this reaction

Answer 4

Kc = 1 / [SO2 ]

Question 5

Gold ions react with copper metal to give gold metal and cupric ions 2Au3+ (aq) + 3Cu(s) ->

Answer 5

Keq = [Cu2+]^3/[Au3+]^2

Question 6

Ammonia is synthesized in the following reaction N2(g) + 3H2(g) -> 2NH3(g) The Kc and Kp values were 0.105 and 0.000028, respectively. At what temperature did this reaction take place?

Answer 6

745 K

Question 7

At 20 degrees C, the vapor pressure of water is 0.0231 atm. What are the values of Kp and Kc for this process? H2O(l) ->

Answer 7

Kp = 0.0231 and Kc = 9.6*10^-4

Question 8

Consider the following equation: CH4(g) + Cl2(g) -> CH3Cl(g) + HCl(g) + 110 kJ
What happens to this reaction when the temperature is increased?

Answer 8

The equilibrium will shift to the left, because the backward reaction requires energy.

Question 9

When the temperature of an exothermic reaction is increased, what happens to the value of the equilibrium constant?

Answer 9

The value of the equilibrium constant decreases.

Question 10

Which statement is NOT correct about the diagram?

Answer 10

At Point 4, Q is equal to KEq. Therefore, the system is at equilibrium and the final concentrations for all of the products can be determined.

Question 11

Suppose you have 28L of components in a flask. The components include 1.5 mol N2, 2.1 mol H2, and 1.8 mol NH3. If the equilibrium equation is N2(g) + 3H2(g) ->

Answer 11

Q = 347; the reaction will move toward the reactants to reach equilibrium

Question 12

Carbon monoxide and hydrogen form CH3OH(g) via the following reaction: CO(g) + 2H2(g) ->

Answer 12

2.03 atm

Question 13

In the reaction in which carbon monoxide and hydrogen form Ch3OH(g), CO(g) + 2H2(g) ->

Answer 13

7.0*10^-3 atm

Question 14

Look at the following partial ICE diagram for the reaction. CH4(g) + H2O(g) ->

Answer 14

CO

Question 15

Look at the following ICE diagram problem. Which gas is the limiting reagent? CH4(g) + H2O(g) ->

Answer 15

CO

Question 16

Suppose that we are looking at the reaction N2O4(g) ->

Answer 16

1.3 atm; 0.48 atm

Question 17

Which of the following correctly shows the relationship between the equilibrium constant, Kp, and the partial pressures for the following reaction: C(s) + CO2(g) ->

Answer 17

Kp = (PCO)^2/(PCO2)

Question 18

Look at the reaction for the synthesis of ammonia from nitrogen and hydrogen.

N2(g) + 3H2(g) ↔ 2NH3(g)

Which of the following does not result in the production of NH3 gas?

Answer 18

Removing some N2 gas from the system.

Question 19

Look at the following reaction involving four gases.

4NH3(g) + 3O2(g) ↔ 2N2(g) + 6H2O(g)

Which statement about this reaction is not correct?

Answer 19

An increase in the number of O2 molecules will cause the value of Q to be greater than Keq.

Question 20

Look at the reaction of H2 and I2 to form HI H2(g) + I2(g) 2HI(g) The expression for the reaction quotient, Q is [HI]^2/[H2][I2]. At equilibrium, Q = Keq = 92.6 Suppose that you have PH2 = 0.208 atm, PI2 = 0.101 atm, and PHI = 3.01 atm. Suppose that you add H2 until its concentration reaches 0.444 atm. What is the correct expression for Kp if you use x for the change in concentration of H2

Answer 20

KP = 92.6 = [HI]2 / [H2 ] [ I2 ] = (3.01 + 2x)2 / (0.444 − x) (0.101 − x)

Question 21

Look at the reaction H2(g) + I2(g) 2HI(g). At equilibrium, Q = Keq = 92.6 Suppose that you have PH2 - 0.217 atm, PI2 = 0.121 atm, and PHI = 2.77 atm, I2 is added until tis concentration reaches 2.33 atm. Letting x be the change in partial pressure of H2, the final quadratic equation for x is 88.6x^2 - 247.2x = 39.2 = 0. What tare the final equilibrium concentrations of all three components

Answer 21

[HI] = 3.11 atm; [H2 ] = 0.047 atm; [ I2 ] = 2.16 atm

Question 22

If a gas is compressed from 5 L to 1 L and the temperature remains constant, what happens to the pressure?

Answer 22

The final pressure is 5 times the original pressure

Question 23

Suppose that the volume for the equilibrium system, N2O4(g) ↔ 2NO2(g), was changed from 4 L to 2 L.

What happens to the value of Q as the system is shifted away from equilibrium by changing the volume? Predict which direction the reaction will proceed to reach equilibrium again.

Answer 23

The value of Q would increase by a factor of 2. In other words, the new value for Q is four times the original value for Q. Therefore, the reverse reaction would occur in order to reach a new equilibrium

Question 24

Look at the diagram that compares the values of Keq and (rising) temperature for endothermic and exothermic reactions. Which statement about this diagram is not correct?

Answer 24

As temperature decreases, the reactants are more favored in an exothermic reaction.

Question 25

Look at the following reaction involving cylopentadiene: 2Cp <==> Cp2 + heat At a lower temperature, the Kc for the reaction is 1.5*10^4. Suppose that you start with 0.38 M Cp2 and 0.0058 M Cp. Which of the following identities for this reaction at a higher temperature could be correct if nothing else was changed in the system?

Answer 25

KC = 5.2 × 10^3