Question

The heat evolved in a reaction of 7.5 g of fe2o3 with enough co is 1.164kj. Calculate h for the reaction.

Answer 1

Answer : The $\Delta H$ for the reaction is, -24.818 KJ

Solution : Given,

Mass of $Fe_2O_3$ = 7.5 g

Molar mass of $Fe_2O_3$ = 159.69 g/mole

Heat evolved = 1.164 KJ

First we have to calculate the moles of $Fe_2O_3$.

$\text{Moles of }Fe_2O_3=\frac{\text{Mass of }Fe_2O_3}{\text{Molar mass of }Fe_2O_3}=\frac{7.5g}{159.69g/mole}=0.0469moles$

The balanced reaction will be,

$Fe_2O_3+3CO\rightarrow 2Fe+3CO_2$

From the balanced reaction we conclude that

As, 0.0469 moles of $Fe_2O_3$ evolved heat = -1.164 KJ

So, 1 mole of $Fe_2O_3$ evolved heat = $\frac{-1.164KJ}{0.0469}=-24.818KJ$

Therefore, the $\Delta H$ for the reaction is, -24.818 KJ