What is the equivalent mass of ${\mathrm{CH}}_3\mathrm{COOH}$?

Equivalent mass:

• The number of parts by mass of the substance that combines with or displaces 1g of hydrogen, 8g of oxygen, and 35.5g of chlorine is known as its equivalent mass.

$\mathrm{Equivalent}\mathrm{mass}=\frac{\mathrm{Atomic}\mathrm{or}\mathrm{molecular}\mathrm{weight}}{\mathrm{n}\mathrm{factor}}$

• The $\mathrm{n}\mathrm{factor}$ is nothing but the valency or number of electrons gained or lost during the reaction or the number of replaceable hydrogen ions (basicity) or the number of replaceable hydroxide ions (acidity).

Calculation:

• The equivalent mass of ${\mathrm{CH}}_3\mathrm{COOH}$ is calculated by first knowing its molecular weight.
• It can be calculated by adding the atomic mass of the atoms in the molecule.

$$\begin{gathered} {\mathrm{CH}}_3\mathrm{COOH}=12.01+3(1.008)+12.01+2(16.00)+1.008 \\ =60.05\mathrm{u} \end{gathered}$$

• The $\mathrm{n}\mathrm{factor}$ of acetic acid is nothing but the number of replaceable hydrogen as it is an acid which is equal to 1.

$\mathrm{i}.\mathrm{e}{\mathrm{CH}}_3\mathrm{COOH}\left(\mathrm{aq}\right)\to {\mathrm{CH}}_3{\mathrm{COO}}^{-}\left(\mathrm{aq}\right)+{\mathrm{H}}^{+}\left(\mathrm{aq}\right)$

• On substituting the value in the equation of equivalent mass we get,

$$\begin{gathered} \mathrm{Equivalent}\mathrm{mass}=\frac{\mathrm{Atomic}\mathrm{or}\mathrm{molecular}\mathrm{weight}}{\mathrm{n}\mathrm{factor}} \\ =\frac{60.05}{1} \\ =60.05\mathrm{u} \end{gathered}$$