Chemistry 9701/41 — May/June 2019

Aqueous solutions of copper(II) salts contain the blue-coloured $[\text{Cu}(\text{H}_2\text{O})_6]^{2+}$ complex ion.
Separate portions of this blue solution react with aqueous sodium hydroxide and with concentrated hydrochloric acid.

Give the following information for each of these reactions.

• reaction with aqueous sodium hydroxide

  • ionic equation
  • type of reaction
  • colour and state of the copper-containing product

• reaction with concentrated hydrochloric acid

  • ionic equation
  • type of reaction
  • colour and state of the copper-containing product

Chloride ions can be identified using aqueous silver nitrate, $\text{AgNO}_3(\text{aq})$.

$0.303\text{ g}$ of a chloride of sulfur is completely hydrolysed with water. All the chlorine atoms present in the chloride of sulfur are converted into chloride ions. The solution is diluted to $100.0\text{ cm}^3$.
A $25.00\text{ cm}^3$ sample of this solution is titrated with $0.0500\text{ mol dm}^{-3}\text{ AgNO}_3(\text{aq})$. The titration requires $22.40\text{ cm}^3$ of $0.0500\text{ mol dm}^{-3}\text{ AgNO}_3(\text{aq})$.

Calculate the empirical formula of the chloride of sulfur. Show all your working.