Chemistry 9701 · AS & A Level · Group 2

Group 2 — practice question

The table shows the values of solubility products, $K_{sp}$, for several Group 2 carbonates.
(a)[1]

Use the table data to outline how the solubility of the Group 2 carbonates changes down the group.

(b(i))[1]

Write an equation for the solubility product equilibrium of $\text{MgCO}_3$. Include state symbols.

(b(ii))[2]

Using the equation from (i), suggest what you would see when a few $\text{cm}^3$ of concentrated $\text{Na}_2\text{CO}_3\text{(aq)}$ are added to a saturated solution of $\text{MgCO}_3$. Explain your answer.

(c)[2]

Use the table values to calculate the solubility of $\text{MgCO}_3$ in water at $298\,\text{K}$, in $\text{g dm}^{-3}$.

(d(i))[2]

Explain why magnesium nitrate decomposes at a lower temperature than barium nitrate.

(d(ii))[1]

A sample of barium nitrate was heated strongly until no further change was seen. A white solid was formed. Write an equation for the effect of heat on barium nitrate.

(d(iii))[2]

When water was added to the white solid from (d)(ii), an alkaline solution formed. Adding sulfuric acid to this solution then gave a white precipitate. Write equations to explain these observations.

Worked solution & mark scheme

This 11-mark question has a full step-by-step worked solution and mark scheme. One marking point: Solubility falls down the group and $K_{sp}$ falls

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