Question

A metal X reacts with zinc chloride to form metal chloride and zinc. The oxide of metal X reacts with both hydrochloric acid and sodium hydroxide to produce salt and water. Identify the metal X.

[0.8 mark]

• A. Iron
• B. Aluminium
• C. Calcium
• D. Magnesium

Answer 1

The correct option is B Aluminium

According to the reactivity series, aluminium is more reactive than zinc. Hence, aluminium will replace zinc from its salt solution. The reaction of aluminium with zinc chloride can be represented as:
$2\mathrm{Al}\left(s\right)+3{\mathrm{ZnCl}}_2\left(\mathrm{aq}\right)\to 2{\mathrm{AlCl}}_3\left(\mathrm{aq}\right)+3\mathrm{Zn}\left(s\right)$

Aluminium oxide shows both acidic as well as basic behaviour. Metal oxides which react with both acids as well as bases to produce salts and water are known as amphoteric oxides. The reaction of aluminium oxide with hydrochloric acid and sodium hydroxide can be represented as:
${\mathrm{Al}}_2{O}_3\left(s\right)+2\mathrm{NaOH}\left(\mathrm{aq}\right)\to 2{\mathrm{NaAlO}}_2\left(\mathrm{aq}\right)+H_{2}O\left(l\right){\mathrm{Al}}_2{O}_3\left(s\right)+6\mathrm{HCl}\left(\mathrm{aq}\right)\to 2{\mathrm{AlCl}}_3\left(\mathrm{aq}\right)+3H_{2}O\left(l\right)$