Question

Write the chemical equation representing the reaction zinc with the following: Dilute hydrochloric acid.

Answer 1

The metal M reacts with the hydrochloric acid$\text{ HCl }$. The reaction between the metal and the hydrochloric acid is as shown below,
$\text{ M + nHCl }\to \text{ MC}{{\text{l}}_{\text{n}}}\text{ + }{{\text{H}}_{\text{2}}}\text{ }\uparrow \text{ }$
- The metal reacts to form the chloride salt of metal and liberates the hydrogen gas. This gas when bubbled through the water.

Complete Solution :
Zinc is a 3-d transition metal. It is brittle, silvery-blue metal. The zinc is ductile and malleable in nature.
- The metal M reacts with the hydrochloric acid $\text{ HCl }$. The reaction between the metal and the hydrochloric acid is as shown below,
$\text{ M + nHCl }\to \text{ MC}{{\text{l}}_{\text{n}}}\text{ + }{{\text{H}}_{\text{2}}}\text{ }\uparrow \text{ }$
- The metal reacts to form the chloride salt of metal and liberates the hydrogen gas. This gas when bubbled through the water.
- The metals undergo the single displacement reaction.in this reaction the one element is substituted or displaced by another element in the compound. This results in the metal salt. The starting compounds are always a pure element.
- The pure zinc metal undergoes the single displacement reaction. The zinc when reacted with the hydrochloric acid it forms zinc chloride and liberates the hydrogen gas. The reaction is as follows,
$\text{ }\begin{matrix} \text{Zn (s)} & \+ & \text{2HCl (aq)} & \to & \text{2ZnC}{{\text{l}}_{\text{2}}} & \+ & {{\text{H}}_{\text{2}}}(g)\text{ } \\\ \text{(Zinc)} & {} & {} & {} & \text{(Zinc Chloride)} & {} & {} \\\ \end{matrix}$

- Here, the 1 atom of zinc displaces two atoms of hydrogen $\text{ }{{\text{H}}^{\text{+}}}\text{ }$ from the hydrochloric acid.
- This is also called the redox reaction. Here the zinc metal in the pure state has the 0 oxidation state loses its two electrons. After losing its electron, the oxidation state of the zinc changes $\text{ +2 }$.
$\text{ Zn }\to \text{ Z}{{\text{n}}^{\text{2+}}}\text{ + }{{\text{e}}^{-}}\text{ }$

- The zinc oxidizes to $\text{Z}{{\text{n}}^{\text{2+}}}$. At the same time, the hydrogen from hydrochloric acid undergoes the reduction as it accepts the electrons from the zinc.

Note: Note that, like hydrochloric acid, nitric acid $\text{ HN}{{\text{O}}_{\text{3}}}\text{ }$ or hydro sulphuric acid $\text{ }{{\text{H}}_{\text{2}}}\text{S}{{\text{O}}_{\text{4}}}\text{ }$ reacts with the metal in the same way. The reaction of metal with nitric acid forms the nitrate salt of metal and with sulphuric acid it forms the sulphate salt of the metal. The reactions can be written as follows,
$\text{ Metal + nitric acid }\to \text{ Metal nitrate + }{{\text{H}}_{\text{2}}}\text{ }\uparrow \text{ }$

- And $\text{ Metal + sulphuric acid }\to \text{ Metal sulphate + }{{\text{H}}_{\text{2}}}\text{ }\uparrow \text{ }$
- The salt forms depend on the nature of the acid used.