Answer: 151 kJ
Explanation:
To calculate the moles :
[tex]\text{Moles of solute}=\frac{\text{given mass}}{\text{Molar Mass}}[/tex]
[tex]\text{Moles of} Fe_3O_4=\frac{61.8g}{231.5g/mol}=0.267moles[/tex]
[tex]Fe_3O_4(s)+4H_2(g)\rightarrow 3Fe(s)+4H_2O(g)[/tex]
It is given that:
0.267 moles of [tex]Fe_3O_4[/tex] absorb energy = 40.3 kJ
Thus 1 mole of [tex]Fe_3O_4[/tex] absorb energy =[tex]\frac{40.3}{0.267}\times 1=151kJ[/tex]
Thus the value of [tex]\Delta H[/tex] for the chemical equation given is 151 kJ