Question

Calculate the standard enthalpy change for the following reaction: 2H2(g) + O2(g) → 2H2O(l)Given the standard enthalpies of formation for H2O (l), H2 (g) and O2 (g) are -285.8 kJ/mol, 0 kJ/mol and 0 kJ/mol, respectively.

Answer 1

To calculate the standard enthalpy change for the reaction, we can use the formula:H =  Hf products  -  Hf reactants where H is the standard enthalpy change, and Hf is the standard enthalpy of formation.For the given reaction:2H2 g  + O2 g   2H2O l The standard enthalpies of formation are:H2O  l : -285.8 kJ/molH2  g : 0 kJ/molO2  g : 0 kJ/molNow, we can plug these values into the formula:H = [2   -285.8 kJ/mol ] - [ 2  0 kJ/mol  +  1  0 kJ/mol ]H =  -571.6 kJ  - 0H = -571.6 kJThe standard enthalpy change for the reaction is -571.6 kJ.