Pearson Edexcel International GCSE (9–1) · CHEMISTRY · Unit
Physical Chemistry
442 practice questions
Topics covered
Practice questions
161–170 of 183 · Easy
Question 161
2 marks · Easy
Answer and see the solution →A student claims that adding a catalyst to a reversible reaction will result in more products being formed at equilibrium. Explain, with reasons, whether the student is correct.
Question 162
3 marks · Easy
Answer and see the solution →The concentrations of reactants and products in a reversible reaction at equilibrium are measured every minute. At minute 4, a catalyst is added. The concentrations at each minute are shown below.
Concentration data (mol/dm³) Time (min) [Reactant] [Product] 0 1.00 0.00 1 0.85 0.15 2 0.75 0.25 3 0.71 0.29 4 0.70 0.30 5 0.70 0.30 6 0.70 0.30 (a)[1 mark]Describe the effect of adding the catalyst on the time taken to reach equilibrium.
(b)[1 mark]Use the data to state the concentrations at equilibrium.
(c)[1 mark]Does adding the catalyst change the equilibrium concentrations? Explain your answer.
Question 163
1 mark · Easy
Answer and see the solution →What does a catalyst do to the rates of the forward and reverse reactions in a reversible process?
Question 164
3 marks · Easy
Answer and see the solution →Nitrogen dioxide, NO₂, and dinitrogen tetroxide, N₂O₄, form a reversible reaction at equilibrium:
(a)[1 mark]State what happens to the colour of the mixture when a catalyst is added.
(b)[1 mark]Explain whether the ratio of NO₂ to N₂O₄ changes after the catalyst is added.
(c)[1 mark]Give a reason for your answer to (b).
Question 165
2 marks · Easy
Answer and see the solution →A reversible reaction reaches equilibrium after 12 minutes. When a catalyst is added, it reaches equilibrium in just 3 minutes. Calculate by what factor the rate of reaching equilibrium has increased. State if the position of equilibrium is affected.
Question 166
1 mark · Easy
Answer and see the solution →For the following equilibrium in solution:
State what will happen to the position of equilibrium if more B is added to the mixture.
Question 167
3 marks · Easy
Answer and see the solution →The following reversible reaction is at equilibrium in a closed container:
A chemist removes some G(g) from the equilibrium mixture.
(a)[1 mark]State how the position of equilibrium will change.
(b)[1 mark]Give a reason for your answer in (a).
(c)[1 mark]Name the principle that explains your answer.
Question 168
2 marks · Easy
Answer and see the solution →A system is at equilibrium with the following reaction:
At equilibrium, the concentration of Z is 4.0 mol/dm^3. If 2.0 mol/dm^3 of Z is suddenly removed, how many moles per dm^3 of Z will form to restore equilibrium? Assume all change is due to the forward reaction.
Question 169
2 marks · Easy
Answer and see the solution →The following reaction is at equilibrium in a sealed container:
Explain, in terms of concentration, what will happen to the position of equilibrium if extra KL(g) is added.
Question 170
3 marks · Easy
Answer and see the solution →The equilibrium below is set up in a sealed vessel:
The graph shows how the concentration of AB(g) changes after some B2(g) is added:
Concentration of AB(g) vs. time after B2(g) is added. (a)[1 mark]Describe what happens to [AB] after B2(g) is added.
(b)[2 marks]Predict and explain the direction in which the position of equilibrium shifts after B2(g) is added.