Copper sulphate solution reacts with sodium hydroxide solution to form a precipitate of copper hydroxide according to the equation:

2NaOH + CuSO₄ ⟶ Na₂SO₄ + Cu(OH)₂↓

(i) What mass of copper hydroxide is precipitated by using 200 g of sodium hydroxide.

[H = 1, O = 16, Na = 23, S = 32, Cu = 64]

(ii) What is the colour of the precipitate formed.

(i)

$\begin{matrix} 2\text{NaOH} & + & \text{CuSO}$4 & \longrightarrow & \text{Na}2\text{SO}4 & + & \text{Cu(OH)}2\downarrow \ 2[23 + 16 & & & & & & 64 + 2[40] \ + 1] & & & & & & = 98 \text{g} \ = 80 \text{ g} & & & & & & \ \end{matrix}

80 g of sodium hydroxide precipitates 98 g of copper hydroxide.

∴ 200 g of sodium hydroxide will precipitate $\dfrac{98}{80}$ x 200 = 245 g of copper hydroxide.

Hence, 245 g. of copper hydroxide is precipitated.

(ii) Pale blue precipitate is formed.