38 gm of mixture of $\mathrm{Li}_2 \mathrm{CO}_3 \& \mathrm{MgCO}_3$ on strong heating showed a weig

Question

38 gm of mixture of $\mathrm{Li}_2 \mathrm{CO}_3 \& \mathrm{MgCO}_3$ on strong heating showed a weight loss of 22 gm . Find the mole $\%$ of $\mathrm{MgCO}_3$ in the given mixture (nearest integer).

Professor PC Thomas Classes · Answer

$\begin{aligned} & (a+b) 	imes 44=22 \quad \Rightarrow \quad a+b=0.5 \ & a 	imes 74+b 	imes 84=38 \ & a=0.4: b=0.1 \ & \% \mathrm{MgCO}_3=\frac{0.1}{0.4+0.1} 	imes 100=20 \%\end{aligned}$