Question

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

Answer 1

To calculate the enthalpy change for the reaction, we can use the formula:H =  Hf products  -  Hf reactants where H is the enthalpy change, and Hf is the standard enthalpy of formation.For the given reaction:2H2 g  + O2 g   2H2O l The standard enthalpy of formation for the products is:2 *  -285.8 kJ/mol  = -571.6 kJ/mol  for 2 moles of H2O The standard enthalpy of formation for the reactants is:2 * 0 kJ/mol  for 2 moles of H2  + 0 kJ/mol  for 1 mole of O2  = 0 kJ/molNow, we can calculate the enthalpy change:H =  -571.6 kJ/mol  -  0 kJ/mol  = -571.6 kJ/molThe enthalpy change for the reaction is -571.6 kJ/mol.