Question

Calculate the standard enthalpy change for the following reaction:2Fe(s) + 3/2O2(g) → Fe2O3(s)Given that the standard enthalpy of formation of Fe2O3(s) is -824 kJ/mol and the standard enthalpy of formation of Fe(s) and O2(g) are 0 kJ/mol.

Answer 1

To calculate the standard enthalpy change for the reaction, we can use the following formula:H reaction  =  Hf products  -  Hf reactants In this case, the reactants are 2 moles of Fe s  and 3/2 moles of O2 g , and the product is 1 mole of Fe2O3 s . The standard enthalpy of formation  Hf  for Fe s  and O2 g  are both 0 kJ/mol, and the Hf for Fe2O3 s  is -824 kJ/mol.H reaction  = [1 mol   -824 kJ/mol ] - [2 mol  0 kJ/mol +  3/2  mol  0 kJ/mol]H reaction  = -824 kJ/mol - 0 kJ/molH reaction  = -824 kJ/molSo, the standard enthalpy change for the reaction is -824 kJ/mol.