Question

What is the enthalpy change for the reaction:2H2(g) + O2(g) → 2H2O(l)Given the following bond enthalpy values: H-H bond = +436 kJ/mol  O=O bond = +495 kJ/mol H-O bond = -463 kJ/molExpress your answer in kJ/mol.

Answer 1

To calculate the enthalpy change for the reaction, we need to consider the bond enthalpies of the reactants and products.For the reactants, we have:2 H-H bonds and 1 O=O bond.For the products, we have:4 H-O bonds  since there are 2 H2O molecules formed .Now, we can calculate the enthalpy change as follows:H = [Sum of bond enthalpies of reactants] - [Sum of bond enthalpies of products]H = [ 2  +436 kJ/mol  +  1  +495 kJ/mol ] - [ 4  -463 kJ/mol ]H =  872 + 495  -  -1852 H = 1367 + 1852H = -485 kJ/molSo, the enthalpy change for the reaction is -485 kJ/mol.