Question

How are the following indicated in a chemical equation?

Evolution of gas

Answer 1

Any chemical change can be expressed as a chemical equation. There are different terms that are used in a chemical equation.

If there is an evolution of gas in a particular chemical reaction, it can be shown as an upward arrow ($\uparrow$) or (g) mentioned adjacent to the gas.

For example:

When a metal reacts with an acid, it gives Hydrogen gas $\left({\mathrm{H}}_2\right)$as a product.

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