Chemistry 9701 · AS & A Level · Group 2

Group 2 — practice question

(a(i))[1]

State how the solubilities of Group 2 hydroxides change as you go down the group.

(a(ii))[3]

Explain which factors cause this variation.

(b)

At $0^\circ\text{C}$, the solubility of $\text{Sr(OH)}_2$ is $3.37 \times 10^{-2}\ \text{mol dm}^{-3}$.

(b(i))[1]

Write the solubility product expression for $\text{Sr(OH)}_2$.

(b(ii))[2]

Calculate the value of $K_{sp}$ at $0^\circ\text{C}$. Include units in your answer.

(c(i))[1]

Write an equation for the thermal decomposition of strontium peroxide, $\text{SrO}_2$.

(c(ii))[3]

Suggest how the temperature at which thermal decomposition of $\text{MO}_2$ occurs changes down Group 2. Explain your answer.

(d(i))[1]

Finish the equation for the thermal decomposition of barium ethanedioate. $ \text{BaC}_2\text{O}_4 \rightarrow \_\_\_\_\_\_\_\_ + \_\_\_\_\_\_\_\_ + \_\_\_\_\_\_\_\_ $

(d(ii))[2]

Describe two observations you would make when ethanedioic acid, $\text{H}_2\text{C}_2\text{O}_4$, is heated with acidified manganate(VII) ions.

Worked solution & mark scheme

This 14-mark question has a full step-by-step worked solution and mark scheme. One marking point: Solubility rises down the group

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