Chemistry 0620 · IGCSE · Separation and purification

Separation and purification — practice question

(a(i))[2]

Give the names of two aqueous solutions that, when mixed, form a precipitate of lead(II) bromide.

(a(ii))[2]

Describe how to obtain a pure sample of lead(II) bromide from the mixture of aqueous solutions in (a)(i).

(a(iii))[3]

Write an ionic equation for the precipitation reaction that makes lead(II) bromide. Include state symbols.

(b)[2]

Describe how to test for sulfur dioxide gas. test reagent observations

(c)[2]

Complete the equation for the thermal decomposition of hydrated cobalt(II) nitrate. $2\text{Co(NO}_3)_2\cdot4\text{H}_2\text{O} \rightarrow \ldots\text{CoO} + \ldots\text{NO}_2 + \text{O}_2 + \ldots\text{H}_2\text{O}$

(d(i))[2]

Describe what else the student should do to make sure that all the water has been removed. No other substances are required.

(d(ii))[4]

Calculate the number of moles of CoSO$_4$ that remains. Calculate the mass of H$_2$O given off. Calculate the number of moles of H$_2$O given off. Determine the value of $x$.

Worked solution & mark scheme

This 17-mark question has a full step-by-step worked solution and mark scheme. One marking point: Lead(II) nitrate solution

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