Question

How will you provide the following information in a chemical equation?

Evolution of gas.

Answer 1

1. Chemical Equation: A chemical equation is a shorthand method to describe the reaction taking place in terms of symbols and formulae of substances involved in the reaction.
2. Representation of physical states of reactants and products: A chemical equation must show the physical states of the substances involved. Solids are represented by the symbol (s), liquids by (l), gases by (g), and aqueous medium by (aq).
3. Representation of evolution of gas: If gas is evolved during a reaction, it is represented by an upward arrow ($\uparrow$).
4. Example: When Zinc ($\mathrm{Zn}$) metal reacts with dilute Sulphuric acid (${\mathrm{H}}_2{\mathrm{SO}}_4$), the Hydrogen (${\mathrm{H}}_2$) gas is evolved along with the production of Zinc sulphate (${\mathrm{ZnSO}}_4$).

$$\begin{gathered} \mathrm{Zn}\left(\mathrm{s}\right)+{\mathrm{H}}_2{\mathrm{SO}}_4\to {\mathrm{ZnSO}}_4\left(\mathrm{aq}\right)+{\mathrm{H}}_2\left(\mathrm{g}\right)\uparrow \\ \mathrm{Zinc}\mathrm{Dil}.\mathrm{Sulphuric}\mathrm{Zinc}\mathrm{Hydrogen} \\ \mathrm{acid}\mathrm{sulphate} \end{gathered}$$