Chemistry 0620 · IGCSE · Preparation of salts

Preparation of salts — practice question

Magnesium sulfate and lead(II) sulfate both count as examples of salts.
(a(i–iv))[5]

(i) State how the student knew the reaction had ended in step 1. (ii) Name the residue from step 2. (iii) A saturated solution is made in step 3. What is a saturated solution? (iv) Explain why magnesium sulfate crystals are formed in step 4.

(b(i–iv))[5]

(i) Calculate the moles of water removed. (ii) Calculate the moles of anhydrous magnesium sulfate left in the crucible. The $M_r$ of anhydrous magnesium sulfate is 120. (iii) Calculate the ratio of moles of anhydrous magnesium sulfate : moles of water. Give your answer as whole numbers. (iv) Suggest the formula of hydrated magnesium sulfate crystals.

(c)[4]

Describe how you would obtain a pure dry sample of lead(II) sulfate crystals from lead(II) nitrate solution and sodium sulfate solution. Include the main steps in your answer.

(d)[2]

Write the ionic equation for the reaction between lead(II) nitrate solution and sodium sulfate solution. Include state symbols.

Worked solution & mark scheme

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