A scientist measures the standard enthalpy change for the following reaction to be 67.9 kJ: Fe2O3(s) + 3 H2(g) →2Fe(s) + 3 H2O(9)
Based on this value and the standard enthalpies of formation for the other substances, the standard enthalpy of formation
of H2O(g) is kJ/mol.

-252.5 kJ/mol = ΔH H2O(g)

Explanation:

ΔH Fe2O3 = -825.5kJ/mol

ΔH H2 = 0kJ/mol

ΔH Fe = 0kJ/mol

Based on Hess's law, ΔH of a reaction is the sum of ΔH of products - ΔH of reactants. For the reaction:

Fe2O3(s) + 3 H2(g) →2Fe(s) + 3 H2O(g)

ΔHr = 67.9kJ/mol = 3*ΔH H2O + 2*ΔHFe - (ΔH Fe2O3 + 3*Δ H2)

67.9kJ/mol = 3*ΔH H2O + 2*0kJ/mol - (ΔH -825.5kJ/mol + 3*Δ H2)

67.9 = 3*ΔH H2O(g) + 825.5kJ/mol

-757.6kJ/mol = 3*ΔH H2O(g)

3

explanation:

they all get energy from eating other animals, dead animals to be more precise.

hienas tends to steal pray from other animals. crows and vultures tend to eat dead animals and leftovers.

hope it ,

bioteacher101