Chemistry 5070 · O Level · Reversible reactions and equilibrium

Reversible reactions and equilibrium — practice question

Carbon dioxide and water vapour are both greenhouse gases present in air.
(a(i))[1]

Name one further greenhouse gas.

(a(ii))[1]

State one environmental issue that could result from an increase in the percentage of carbon dioxide in the air.

(b)[1]

Draw the dot-and-cross diagram to represent bonding in a molecule of carbon dioxide. Show only the outer-shell electrons.

(c)[1]

Some power stations burn methane, $\text{CH}_4$. Write the equation for the complete combustion of methane.

(d(i))[2]

The carbon dioxide made in power stations can be removed by a reversible reaction with water, $\text{CO}_2(g) + \text{H}_2\text{O}(l) \rightleftharpoons \text{H}_2\text{CO}_3(aq)$. The forward reaction is exothermic. The concentration of carbon dioxide is increased. The temperature is kept constant. Predict and explain how the position of equilibrium changes.

(d(ii))[2]

The water temperature is raised. All other conditions are kept constant. Predict and explain how the position of equilibrium changes.

(e(i))[1]

Carbonic acid, $\text{H}_2\text{CO}_3(aq)$, is a weak acid. What is meant by the term weak in weak acid?

(e(ii))[1]

Carbonic acid contains a small concentration of carbonate ions, $\text{CO}_3^{2-}(aq)$. If carbonic acid is pumped deep underground, the $\text{CO}_3^{2-}(aq)$ will react with metal ions to form insoluble carbonates. Write the ionic equation for the reaction of magnesium ions with $\text{CO}_3^{2-}(aq)$.

Worked solution & mark scheme

This 10-mark question has a full step-by-step worked solution and mark scheme. One marking point: methane ($\text{CH}_4$)

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