Question

The standard heat of combustion of $Alis-837.8kJmo{l}^{-1}at{25}^{\circ }C$. If $Al$ reacts with $O_{2}at{25}^{\circ }C$, the formation of $0.150molofA{l}_2{O}_3$ release $xkJ$ of heat.

x is ....................

Answer 1

$Al+\frac{3}{2}{O}_2\to \frac{1}{2}A{l}_2{O}_3$
$\stackrel{27g}{\Delta H}=\stackrel{51g}{-837.8kJmo{l}^{-1}}$
Formation of 0.150 mol of $A{l}_2{O}_{3}gave=250kJ$
Hence answer is 250 kJ