Question

0.607 g of the silver salt of a tribasic acid on combustion deposited 0.37 g of pure silver Calculate the molecular weight of the acid.

Answer 1

$A{g}_{3}A⟶3Ag+A$

$3$ moles of $Ag$ combine with $1$ mole of$A$

Mass of $Ag=0.37gm$

Mass of $A=0.607-0.37=0.237gm$

Moles of $Ag=\frac{0.37}{108}=0.003426$

Moles of $A=\frac{0.003426}{3}=0.001142$

Molar mass of $A=\frac{0.237}{0.001142}=207.53gm$

A tribasic acid has $3$ atoms of $H$

Molar mass of the acid $=3+207.53=210.53g/mol$