Chemistry 9701 · AS & A Level · Group 2

Group 2 — practice question

The reaction scheme illustrates several reactions of calcium.
(a(i))[1]

Reaction 1 gives $\mathrm{Ca(NO_3)_2}$ plus one further product. Name the other product.

(a(ii))[1]

Write an equation for the thermal decomposition of $\mathrm{Ca(NO_3)_2(s)}$.

(a(iii))[1]

State the trend in the thermal stability of the Group 2 nitrates down the group.

(a(iv))[1]

In reaction 3, excess $\mathrm{CO_2}$ is bubbled through water containing $\mathrm{CaCO_3}$. A solution of $\mathrm{Ca(HCO_3)_2(aq)}$ is produced. Construct an equation for reaction 3.

(b)[1]

Describe how $\mathrm{Ca(OH)_2}$ is used in agriculture.

(c(i))[1]

In reaction 4, calcium carbide, $\mathrm{CaC_2}$, is made from $\mathrm{CaO}$. $\mathrm{CaC_2}$ contains the $\mathrm{C_2^{2-}}$ anion. Each carbon atom in $\mathrm{C_2^{2-}}$ is $sp$ hybridised. Describe how $sp$ hybridised orbitals are formed.

(c(ii))[2]

Sketch a diagram showing how two $sp$ hybrid orbitals can make a sigma ($\sigma$) bond.

(d)

The flowchart presents some reactions of $\text{CaC}_2$.

(d(i))[2]

Reaction 5 can be used to make $\text{NH}_3$. $\text{CaCN}_2 + 3\text{H}_2\text{O} \rightarrow \text{CaCO}_3 + 2\text{NH}_3$ Calculate the minimum mass, in tonnes, of calcium cyanamide, $\text{CaCN}_2$, that is required to produce $1.50 \times 10^6$ tonnes of $\text{NH}_3$. Show your working. $1$ tonne $= 1.00 \times 10^6\ \text{g}$.

(d(ii))[3]

Draw the structures of the organic products formed in the reactions below: $\text{CH}_3\text{CH}_2\text{Br}$ with $\text{NaCN}$ dissolved in ethanol, then $\text{H}_2\text{SO}_4$(aq) heated under reflux. A carbonyl compound reacted with $\text{NaCN}$ and $\text{HCN}$.

Worked solution & mark scheme

This 13-mark question has a full step-by-step worked solution and mark scheme. One marking point: Hydrogen gas or $\mathrm{H_2}$

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