Question

Calculate the equivalent weight of the following substance as acid or base.

$Al{\left(OH\right)}_4^{-}$
If $M$ is the molecular weight and $E$ the equivalent weight , then :

• A. $E=\frac{M}{4}$
• B. $E=\frac{M}{3}$
• C. $E=\frac{M}{2}$
• D. none of these

Answer 1

The correct option is A $E=\frac{M}{4}$

1 mole of $Al{\left(OH\right)}_4^{-}$contains 4 moles of replaceable hydroxide ions.

Hence, its equivalent weight is equal to one fourth of its molecular weight.

$\text{Equivalent mass of a base}=\frac{\text{Molar mass of the base}}{\text{Number of replaceable hydroxide ions}}$

$E=\frac{\text{M}}{4}$

Hence the correct option is A.