`0.1914 g` of an organic acid is dissolved in about `20 mL` of water. `25 mL` of `0.12 N NaOH` is required for complete neutralization of the acid solution. The equivalent mass of the acid is

Options

A. `65.0`
B. `64.0`
C. `62.5`
D. `63.8`

Answer

D

Explanation

According to the law of equivalence,
`("Milliequival ents")_(NaOH) = ("Milliequi valents")_(o .acid)`
`= (0.12)(25) = 3`
`:.` Equivalents of organic acid `= (3)/(1000)`
This implies that `3 xx 10^(-3)` equivalents of acid weigh `0.1914 g`.
Thus,
`1` equivalent of acid will weigh `(0.1914 g)/(3 xx 10^(-3) eq) = 63.8 g eq^(-1)`
Hence, the equivalent mass of acid is `63.8 u`.