Chemistry 0620 · IGCSE · Identification of ions and gases

Identification of ions and gases — practice question

(a(i))[2]

Name any two aqueous solutions that, when combined, give a precipitate of barium sulfate.

(a(ii))[2]

Describe how a pure sample of barium sulfate can be obtained from the mixed aqueous solutions in (a)(i).

(a(iii))[3]

Write the ionic equation for the precipitation reaction that forms barium sulfate, and include state symbols.

(b)[2]

Name the dilute acid and one other reagent that react together to form copper(II) sulfate.

(c(i))[1]

Describe a test for oxygen and state the observation.

(c(ii))[2]

Complete the equation for the thermal decomposition of hydrated copper(II) nitrate. $2\text{Cu(NO}_3\text{)}_2\cdot3\text{H}_2\text{O} \rightarrow \ldots\text{CuO} + \ldots\text{NO}_2 + \text{O}_2 + \ldots\text{H}_2\text{O}$

(d(i))[1]

State why the student repeats heating and weighing until the mass stays constant.

(d(ii))[4]

Work out the value of $x$ by finding the number of moles of ZnSO₄ remaining, the mass of H₂O given off, the number of moles of H₂O given off, and then 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: A soluble barium salt, such as barium chloride or barium nitrate

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