Question

What is equivalent weight formula?

Answer 1

1. Equivalent weight is the mass of one equivalent of a substance. It is also known as gram equivalent.
2. The equivalent of any substance is given by the charge it carries on itself.
3. Thus, the equivalent weight is obtained by the ratio of the molar mass of the substance and the number of equivalents.
4. It can be mathematically represented as
   $\mathrm{Equivalent}\mathrm{weight}=\frac{\mathrm{Molar}\mathrm{Mass}}{\mathrm{number}\mathrm{of}\mathrm{equivalents}}$.
5. The number of equivalents implies the charge carried by the compound. For example: For $\mathrm{Ca}{\left(\mathrm{OH}\right)}_2$, the number of equivalents is 2 as the charge on $\mathrm{Ca}$ is 2+ and 2 equivalents of $\left({\mathrm{OH}}^{-}\right)$ is present.
6. The molecular formula of calcium hydroxide is = Ca(OH)₂.
   Its molecular mass is =40+(16+1)×2=40+17×2=74u
7. $\mathrm{Equivalent}\mathrm{weight}=\frac{74\mathrm{u}}{2}=37\mathrm{u}$