Chemistry 9701 · AS & A Level · Group 2

Group 2 — practice question

The table gives solubility product, $K_{sp}$, values for several Group 2 carbonates.
(a)[1]

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

(b(i))[1]

Write an equation for the equilibrium involved in the solubility product of MgCO$_3$. State symbols are required.

(b(ii))[2]

With reference to your equation in (i), suggest the observation when a few cm$^3$ of concentrated Na$_2$CO$_3$(aq) are added to a saturated solution of MgCO$_3$. Explain your answer.

(c)[2]

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

(d(i))[2]

Explain why $\text{Magnesium nitrate}$ decomposes at a lower temperature than $\text{barium nitrate}$.

(d(ii))[1]

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

(d(iii))[2]

When water was added to the white solid produced in (d)(ii), an alkaline solution was produced. Adding sulfuric acid to this solution produced 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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