Chemistry 0620 · IGCSE · Preparation of salts

Preparation of salts — practice question

The question is about salts.
(a)[5]

Describe the method you would use to make a pure sample of zinc sulfate crystals. Your response should include the practical steps, how you would check that every last trace of the dilute sulfuric acid has reacted, and an equation for the reaction.

(b(i))[2]

Describe a test for sulfur dioxide. Your answer should give the test used and the observations expected.

(b(ii))[2]

Complete the equation for the thermal decomposition of hydrated iron(II) sulfate.\n\n$\ldots\text{FeSO}_4\cdot 7\text{H}_2\text{O} \rightarrow \text{Fe}_2\text{O}_3 + \text{SO}_2 + \text{SO}_3 + \ldots\text{H}_2\text{O}$

(c(i))[2]

Describe how the student can make sure that every trace of water has been removed.

(c(ii))[4]

Determine the value of $x$ by following these steps: calculate the amount of BaCl$_2$ remaining in moles; calculate the mass of H$_2$O lost; calculate the amount of H$_2$O lost in moles; work out the value of $x$.

Worked solution & mark scheme

This 15-mark question has a full step-by-step worked solution and mark scheme. One marking point: Keep adding zinc carbonate to sulfuric acid until it no longer dissolves / there is no more effervescence

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