Question

Name two metals that can displace hydrogen from Hydrochloric acid.

Answer 1

1. Reactivity series of metals

Some metals are chemically very reactive, whereas some are less reactive or unreactive. The highly reactive metals displace the less reactive metals. The arrangement of metals in a vertical column in the order of decreasing reactivities is called the reactivity series of metals.

2. Two metals that displace hydrogen

The metals replacing hydrogen from Hydrochloric acid are zinc (Zn) and aluminium (Al).

1. The reaction of zinc (Zn) with Hydrochloric acid (HCl) is shown below:

$$\begin{gathered} \mathrm{Zn}\left(\mathrm{s}\right)+2\mathrm{HCl}\left(\mathrm{aq}\right)\to {\mathrm{ZnCl}}_2\left(\mathrm{s}\right)+{\mathrm{H}}_2\left(\mathrm{g}\right) \\ \mathrm{Zinc}\mathrm{Hydrochloric}\mathrm{acid}\mathrm{Zinc}\mathrm{chloride}\mathrm{Hydrogen} \end{gathered}$$

2. The reaction of aluminium (Al) with Hydrochloric acid (HCl) is shown below:

$$\begin{gathered} 2\mathrm{Al}\left(\mathrm{s}\right)+6\mathrm{HCl}\left(\mathrm{aq}\right)\to 2{\mathrm{AlCl}}_3\left(\mathrm{s}\right)+3{\mathrm{H}}_2\left(\mathrm{g}\right) \\ \mathrm{Aluminium}\mathrm{Hydrochloric}\mathrm{acid}\mathrm{Aluminium}\mathrm{Hydrogen} \\ \mathrm{chloride} \end{gathered}$$

Hence, Zinc and Aluminium both can displace hydrogen from Hydrochloric acid because both metals are highly reactive.