Chemistry 5070 · O Level · Reversible reactions and equilibrium

Reversible reactions and equilibrium — practice question

A scientist studies the thermal decomposition of calcium carbonate in a closed vessel. A dynamic equilibrium mixture is formed. $\text{CaCO}_3(s) \rightleftharpoons \text{CaO}(s) + \text{CO}_2(g)$
(a)[2]

What does the term dynamic equilibrium mean?

(b)[2]

The pressure of the equilibrium mixture is reduced. The temperature of the closed system is held constant. Predict and explain how the composition of the equilibrium mixture will change.

(c)[1]

The temperature of the equilibrium mixture is increased. The pressure inside the closed system is kept constant. The equilibrium position shifts to the right-hand side. What conclusion can be drawn about the enthalpy change of the reaction?

(d(i))[2]

Calcium carbonate reacts with dilute nitric acid to produce three substances, X, Y and Z. X is a salt. Y is a colourless gas. Z is a colourless liquid. Name Y and describe a test for this gas.

(d(ii))[2]

State the identity of Z and describe a chemical test for this liquid.

(d(iii))[1]

Write the equation for calcium carbonate reacting with nitric acid.

Worked solution & mark scheme

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