Question

$0.701g$ of silver salt of a dibasic acid on ignition yielded $0.497g$ of metallic silver. Molecular weight of the acid is $(Ag=108)$

• A. 90.7
• B. 304.7
• C. 88.7
• D. 197.7

Answer 1

Answer: (A)

$H_{2}A\to \underset{0.701}{A{g}_{2}A}\to \underset{0.497}{2Ag}$

Molecular weight of silver salt $=\frac{0.10}{0.497}\times 2\times 108=304.7$

Molecular weight of acid $=304.7-2\times$ atomic mass of silver $+$ $2\times$ atomic mass of hydrogen $=304.7-2\times 108+2\times 1=90.7$ Alternatively,

Equivalent mass of acid $=\frac{108\times \text{ Mass of silver salt }}{\text{ Mass of Ag metal }}-107$

Equivalent mass of acid $=\frac{108\times 0.701}{0.497}-107=45.33$

Molecular mass $=45.33\times 2\approx 90.7$