Question

$0.59g$ of the silver salt of an organic acid (molar mass $210$) on ignition gave $0.36g$ of pure silver. The basicity of the acid is

• A. 2
• B. 3
• C. 4
• D. 5

Answer 1

Answer: (B)

$\underset{\text{ Acid }}{H_n}\times \underset{\mathrm{AgN}{\mathrm{O}}_3}{\overset{\mathrm{N}{\mathrm{H}}_3}{\to }}\underset{\text{Ag salt}}{\mathrm{AgN}}\times \stackrel{\mathrm{\Delta }}{\to }\underset{Ag}{\mathrm{nAg}}$
$M-n\times \underset{w_{19}}{1}+n\times 108$
$n\times \frac{w_1}{m-n\times 1+n\times 108}\frac{W}{108}g$
Given:
$W_1=0.59g$
$W_2=0.36g$
$m=210$
$M=\frac{n\times w_1\times 108}{w_2}-107n$
$210=\frac{n\times 0.59\times 108}{0.36}-107n$
$\therefore 210=177n-107n$
$\therefore n=3$