Chemistry 9701 · AS & A Level · Nitrogen and sulfur

Nitrogen and sulfur — practice question

Hydrogen is the most plentiful element in the Universe, although on Earth only tiny amounts of molecular hydrogen have been found naturally. Hydrogen is made on a very large scale for the chemical industry, and it is also considered a possible fuel that could replace fossil fuels in internal combustion engines.
(a)[1]

State one large scale use of hydrogen in the chemical industry.

(b(i))

Using the information above, state and explain how the equilibrium position changes when the applied pressure is increased. The reaction is: $\text{CH}_4(g) + \text{H}_2\text{O}(g) \rightleftharpoons \text{CO}(g) + 3\text{H}_2(g)$, $\Delta H = +206\,\text{kJ mol}^{-1}$.

(b(ii))[4]

Using the information above, state and explain how the equilibrium position changes when the equilibrium is cooled. The reaction is: $\text{CH}_4(g) + \text{H}_2\text{O}(g) \rightleftharpoons \text{CO}(g) + 3\text{H}_2(g)$, $\Delta H = +206\,\text{kJ mol}^{-1}$.

(c)[2]

What effect will increasing the pressure have on the rate of reaction? Explain your answer.

(d(i))

Give the expression for $K_c$ for the reaction: $\text{CO}(g) + \text{H}_2\text{O}(g) \rightleftharpoons \text{CO}_2(g) + \text{H}_2(g)$. It is given that $K_c = 6.40 \times 10^{-1}$ at $1100\,\text{K}$.

(d(ii))[5]

Calculate the number of moles of each substance present in the equilibrium mixture at $1100\,\text{K}$. A mixture containing $0.40$ mol of $\text{CO}$, $0.40$ mol of $\text{H}_2\text{O}$, $0.20$ mol of $\text{CO}_2$ and $0.20$ mol of $\text{H}_2$ was placed in a $1\,\text{dm}^3$ flask and left until equilibrium was reached. Reaction: $\text{CO}(g) + \text{H}_2\text{O}(g) \rightleftharpoons \text{CO}_2(g) + \text{H}_2(g)$.

Worked solution & mark scheme

This 12-mark question has a full step-by-step worked solution and mark scheme. One marking point: Acceptable industrial or everyday use of catalysts, e.g. Haber process, hydrogenation, hydrocracking or margarine manufacture

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