Chemistry 9701 · AS & A Level · Nitrogen and sulfur

Nitrogen and sulfur — practice question

Phosphorus, sulfur and chlorine are each able to react with oxygen and produce oxides.
(a(i))[1]

Write an equation to represent phosphorus reacting with excess oxygen.

(a(ii))[2]

Describe how phosphorus(V) oxide reacts with water.

(a(iii))[1]

State the bonding and structure present in solid phosphorus(V) oxide.

(b(i))[2]

Explain what is meant by the term weak Brønsted-Lowry acid.

(b(ii))[1]

Write an equation for $\text{SO}_2$ reacting with water.

(b(iii))[1]

$\text{SO}_2$ reacts with $\text{NO}_2$ in the atmosphere to make $\text{SO}_3$ and $\text{NO}$. $\text{NO}$ is then oxidised in air to produce $\text{NO}_2$. The reactions are: $\text{SO}_2 + \text{NO}_2 \rightarrow \text{SO}_3 + \text{NO}$ $2\text{NO} + \text{O}_2 \rightarrow 2\text{NO}_2$ State the function of $\text{NO}_2$ in this two-stage process.

(c(i))[1]

Sulfur dioxide emissions from coal-fired power stations can be cut by adding powdered limestone to the coal. In reaction 1, limestone is heated to produce $\text{CaO}$. That then reacts with $\text{SO}_2$ and $\text{O}_2$ to form $\text{CaSO}_4$ in reaction 2. Reaction 1: $\text{CaCO}_3(s) \rightarrow \text{CaO}(s) + \text{CO}_2(g)$ Reaction 2: $\text{CaO}(s) + \text{SO}_2(g) + \tfrac{1}{2}\text{O}_2(g) \rightarrow \text{CaSO}_4(s)$ State the kind of reaction taking place in reaction 1.

(c(ii))[2]

Use the data to calculate the enthalpy change for reaction 2. $\Delta H_f$ values (kJ mol$^{-1}$): $\text{CaO}(s) = -635$, $\text{SO}_2(g) = -297$, $\text{CaSO}_4(s) = -1434$ Enthalpy change for reaction 2 = .......... $\text{kJ mol}^{-1}$.

(d(i))[1]

Draw a dot-and-cross diagram for $\text{Cl}_2\text{O}$, showing only outer-shell electrons.

(d(ii))[1]

To prepare $\text{ClO}_2$, $\text{NaClO}_2$ is reacted with $\text{Cl}_2$. Write the oxidation state of chlorine in each species in the boxes provided. $2\text{NaClO}_2 + \text{Cl}_2 \rightarrow 2\text{ClO}_2 + 2\text{NaCl}$

(d(iii))[4]

$\text{Cl}_2\text{O}_6(g)$ is formed when $\text{ClO}_2(g)$ reacts with $\text{O}_3(g)$. $2\text{ClO}_2(g) + 2\text{O}_3(g) \rightleftharpoons \text{Cl}_2\text{O}_6(g) + 2\text{O}_2(g)$ $\Delta H = -216\,\text{kJ mol}^{-1}$ The reaction is carried out at $500\,\text{K}$ and $100\,\text{kPa}$. State and explain what happens to the yield of $\text{Cl}_2\text{O}_6(g)$ when the experiment is performed: • at $1000\,\text{K}$ and $100\,\text{kPa}$ • at $500\,\text{K}$ and $500\,\text{kPa}$

(e(i))[2]

Suggest the bonding present in the oxide of E. Explain your answer.

(e(ii))[2]

Suggest the bonding present in the chloride of E. Explain your answer.

Worked solution & mark scheme

This 21-mark question has a full step-by-step worked solution and mark scheme. One marking point: The correct equation is $\mathrm{P_4 + 5O_2 \to P_4O_{10}}$

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