Question 1

The Haber process can be represented by the equation:

N₂(g)+3H₂(g)↔2NH₃(g)

What will the effect be on the position of equilibrium and the Kc value if the pressure is decreased on the reaction vessel?

Accepted Answer

Kc is unchanged but equilibrium shifts to the left.

Answer

Kc decreases and equilibrium shifts to the left.

Answer

Kc is unchanged but equilibrium shifts to the right.

Answer

Kc increases and equilibrium shifts to the left.

Question 2

An acidic solution with a pH of 2 was diluted by taking 10 cm³of it and adding it to 90 cm³ of distilled water.

What would the pH of the solution be after this dilution?

Accepted Answer

3

Answer

5

Answer

4

Answer

2

Question 3

There are multiple ways to define oxidation and reduction. Choose the correct combination of terms which both describe the process of reduction.

Accepted Answer

The loss of oxygen OR the gain of electrons.

Answer

The gain of oxygen OR the loss of electrons.

Answer

The loss of hydrogen OR the gain of electrons.

Answer

The loss of oxygen OR the loss of hydrogen.

Question 4

Which statement about chemical equilibria implies they are dynamic?

Accepted Answer

The reactants and products continue to react.

Answer

The position of equilibrium constantly changes.

Answer

The concentrations of the reactants and products continue to change.

Answer

The rates of forward and backward reactions change.

Question 5

The sequence of diagrams represents the system as time passes for a gas phase reaction in which reactant X is converted to product Y.

Which statement is correct?

Accepted Answer

At t= 10 minutes the system has reached a state of equilibrium.

Answer

At t= 7 seconds the reaction has reached completion.

Answer

At t= 5 days the rate of the forward reaction is less than the rate of the backward reaction.

Answer

At t= 5 days the rate of the forward reaction is greater than the rate of the backward reaction.

Question 6

Consider the endothermic reaction below.

5CO (g) + I₂O₅(g) = 5CO₂(g) + I₂(g)

According to Le Chatelier’s principle, which change would result in an increase in the amount of CO₂?

Accepted Answer

Increasing the temperature

Answer

Decreasing the temperature

Answer

Increasing the pressure

Answer

Decreasing the pressure

Question 7

What effect will an increase in temperature have on the Kc value and the position of equilibrium in the following reaction?

N₂ (g)+ 3H₂ (g) = 2NH₃ (g) ΔH= –92 kJ

Accepted Answer

Kc decreases and equilibrium position shifts to the left

Answer

Kc increases and equilibrium position shifts to the left

Answer

Kc increases and equilibrium position shifts to the right

Answer

Kc decreases and equilibrium position shifts to the right

Question 8

What is the effect of an increase of temperature on the yield and the equilibrium constant for the following reaction?

2H₂(g)+ CO(g) = CH₃OH(l) ∆H^O = –128 kJ

Accepted Answer

yield decreases and Kc decreases

Answer

yield decreases and Kc increases

Answer

yield increases and Kc decreases

Answer

yield increases and Kc increases

Question 9

What changes occur when the temperature is increased in the following reaction at equilibrium?

Br₂(g) + Cl₂(g) = 2BrCl (g) ∆H^ο = +14 kJ mol–1

Accepted Answer

The position of equilibrium shifts towards the products and the value of equilibrium constant increases.

Answer

The position of equilibrium shifts towards the reactants and the value of equilibrium constant decreases.

Answer

The position of equilibrium shifts towards the products and the value of equilibrium constant decreases.

Answer

The position of equilibrium shifts towards the reactants and the value of equilibrium constant increases.

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