Question

$1.0$ g of a monobasic acid when completely acted upon Mg gave $1.301$ g of anhydrous Mg salt. Equivalent weight of acid is

• A. $35.54$
• B. $36.54$
• C. $17.77$
• D. $18.27$

Answer 1

Answer: (B)

$\frac{\text{Ew of acid}}{\text{Ew of salt of Mg}}=\frac{\text{Weight of acid}}{\text{Weight of salt}}$
$Mg+2HCl$ (monobasic acid) $\to MgC{l}_2+H_2$
Let $Ew$ of acid $=Ew$ of $H+Ew$ of acid radical
$\therefore$ $Ew$ of salt of $Mg=Ew$ of $Mg+Ew$ of acid radical
$\therefore \frac{\text{Ew of acid}}{\text{Ew of Mg salt}}=\frac{\text{Weight of acid}}{\text{Weight of Mg salt}}$
$\Rightarrow \frac{\text{Ew of H + Ew of acid radical (E)}}{\text{Ew of Mg + Ew of acid radical (E)}}=\frac{1.0}{1.301}$
$\Rightarrow \frac{1+E}{12+E}=\frac{1.0}{1.301}$
$\therefore E=35.54$
$\therefore$ $Ew$ of acid $=Ew$ of $H+Ew$ of acid radical
$=1+35.54=36.54$