Question

How much heat will be required to make $2kg$ of calcium carbide $\left(Ca{C}_2\right)$ according to the following reaction?
$CaO\left(s\right)+3C\left(s\right)\to Ca{C}_2+CO\left(g\right)$
The heats of formation of $CaO\left(s\right),Ca{C}_2\left(s\right)$ and $CO\left(g\right)$ are $-151.6,-14.2,-26.4kcal$ respectively.

Answer 1

$\Delta H=\sum {\Delta H}_{f\left(products\right)}^o-\sum {\Delta H}_{f\left(reactants\right)}^o$
$=[\Delta H_{\left(Ca{C}_2\right)}^o+4\Delta H_{\left(CO\right)}^o]-[\Delta H_{\left(CaO\right)}^o+2\Delta H_{\left(C\right)}^o]$
$[-14.2-26.4]-[-151.6+3\times 0]$
$=-111.0kcal$
For formation o f$64g$ of $Ca{C}_2$ $111.0kcal$ of heat is required.
So, heat required for making $2000g$ of
$Ca{C}_2=\frac{111.0}{64}\times 2000=3468.75kcal$