Question

The reaction of Fe3O4(s) with hydrogen(g) to form iron(s) and water(g) proceeds as follows: Fe3O4(s) + 4 H2(g) 3 Fe(s) + 4 H2O(g) When 61.8 grams of Fe3O4(s) react with sufficient H2(g) , 40.3 kJ of energy are absorbed . What is the value of H for the chemical equation given?

Answer 1

Answer:  151 kJ

Explanation:

To calculate the moles :

$\text{Moles of solute}=\frac{\text{given mass}}{\text{Molar Mass}}$  

$\text{Moles of} Fe_3O_4=\frac{61.8g}{231.5g/mol}=0.267moles$

$Fe_3O_4(s)+4H_2(g)\rightarrow 3Fe(s)+4H_2O(g)$

It is given that:

0.267 moles of $Fe_3O_4$ absorb energy = 40.3 kJ

Thus 1 mole of $Fe_3O_4$ absorb energy =$\frac{40.3}{0.267}\times 1=151kJ$  

Thus the value of $\Delta H$ for the chemical equation given is 151 kJ