The total weight lost when 3 moles of $FeS{O}_4\cdot 7H_{2}O$ is heated to form $F{e}_2{O}_3$ is _______g. 

(given atomic weight of $Fe=56, O=16, S=32, H=1$)

$FeS{O}_4.7H_{2}O\stackrel{\Delta }{\to }F{e}_2{O}_3+S{O}_2+S{O}_3+14H_{2}O$

For 2 moles weight loss= 1 mole $S{O}_2+$ 1 Mole $S{O}_3+$ 14 mole $H_{2}O$ 

$$\begin{gathered} =64+80+(14\times 18)=396gm \\ \therefore For3molesweightloss=594gm \end{gathered}$$