Question

Calculate the standard enthalpy change for the reaction: 2H2(g) + O2(g) → 2H2O(l)Given the standard enthalpies of formation are: ΔHf°(H2O(l)) = -285.8 kJ/mol ΔHf°(H2(g)) = 0 kJ/mol ΔHf°(O2(g)) = 0 kJ/mol Assume all reactants and products are at standard state conditions.

Answer 1

To calculate the standard enthalpy change for the reaction, we can use the following equation:H reaction  =  Hf products  -  Hf reactants For the given reaction:2H2 g  + O2 g   2H2O l The standard enthalpies of formation are:Hf H2O l   = -285.8 kJ/molHf H2 g   = 0 kJ/molHf O2 g   = 0 kJ/molNow, we can plug these values into the equation:H reaction  = [2  Hf H2O l  ] - [2  Hf H2 g   + Hf O2 g  ]H reaction  = [2   -285.8 kJ/mol ] - [2   0 kJ/mol  +  0 kJ/mol ]H reaction  =  -571.6 kJ/mol  -  0 kJ/mol H reaction  = -571.6 kJ/molThe standard enthalpy change for the reaction is -571.6 kJ/mol.