Chemistry 0620 · IGCSE · Preparation of salts

Preparation of salts — practice question

A soluble salt may be prepared by reacting a metal carbonate with a dilute acid.
(a)[1]

State the formula of the dilute acid that reacts with a metal carbonate to produce a nitrate salt.

(b(i))[1]

Why is it necessary to add the iron(II) carbonate in excess in step 2?

(b(ii))[2]

State two observations in step 2 that would indicate iron(II) carbonate was present in excess.

(b(iii))[1]

Describe what should be done in step 3 to achieve the highest possible crystal yield.

(b(iv))[2]

A saturated solution is produced in step 4. Describe what is meant by a saturated solution.

(b(v))[1]

Name a different compound that could replace iron(II) carbonate to make hydrated iron(II) sulfate crystals from dilute sulfuric acid.

(c)[3]

Work out the value of $x$ by following these steps: find the mass of one mole of FeSO$_4$; find the mass of H$_2$O in one mole of FeSO$_4\cdot$xH$_2$O; determine the value of $x$.

(d(i))[1]

State the name of the method used to make salts in this way.

(d(ii))[1]

Give the observation the student would make in step 1.

(d(iii))[3]

Write the ionic equation for the reaction between aqueous silver nitrate and aqueous potassium bromide. Include state symbols.

(e)[3]

Calculate the volume of chlorine gas, in cm$^3$, that reacts to produce 2.34 g of NaCl.

(f(i))[3]

Explain this in terms of structure and bonding.

(f(ii))[1]

Name the product formed at the positive electrode when electricity is passed through molten sodium chloride.

(f(iii))[2]

State the type of change that occurs at the positive electrode in (ii). Explain your answer in terms of electron transfer.

(f(iv))[1]

Describe what else can be done to sodium chloride so that it can conduct electricity.

Worked solution & mark scheme

This 26-mark question has a full step-by-step worked solution and mark scheme. One marking point: HNO₃

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