Question 7

7.1 A learner dissolves ammonium chloride (NH₄Cℓ) crystals in water and measures the pH of the solution.

7.1.1 Define the term hydrolysis of a salt. (2)

7.1.2 Will the pH of the solution be GREATER THAN, SMALLER THAN or EQUAL TO 7? Write a relevant equation to support your answer. (3)

7.2 A sulphuric acid solution is prepared by dissolving 7,35 g of H₂SO₄(ℓ) in 500 cm³ of water.

7.2.1 Calculate the number of moles of H₂SO₄ present in this solution. (2)

Sodium hydroxide (NaOH) pellets are added to the 500 cm³ H₂SO₄ solution.
The balanced equation for the reaction is:

H₂SO₄(aq) + ₂NaOH(s) → Na₂SO₄(aq) + ₂H₂O(ℓ)

After completion of the reaction, the pH of the solution was found to be 1,3.

Assume complete ionisation of H₂SO₄.

7.2.2 Calculate the mass of NaOH added to the H₂SO₄ solution. Assume that the volume of the solution does not change. (9)

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