Question

1.52 g of the silver salt of an organic acid (M.M = 90 g/mol) when ignited, gives 1.08 g of pure silver. The basicity of the acid will be:

• A. 1
• B. 2
• C. 3
• D. 4

Answer 1

The correct option is B 2

Let the balanced chemical equation be,

$H_{n}A\to A{g}_{n}A\to nAg$
Mass of the silver salt = 1.52 g
Mass of the Ag residue = 1.08 g
Molar mass of (Organic acid) = 90 g/mol
Molar mass of (Salt) = 90 - n + 108 n = 90 + 107 n g/mol
where n is the replaceable H or basicity of the acid
Hence moles of the silver salt = $\frac{1.52}{90+107n}$
moles of Ag $=\frac{1.08}{108}$
applying POAc on Ag
$\left(\frac{1.52}{90+107n}\right)\times n=\frac{1.08}{108}$
n = 2