Question: What is the change in enthalpy (ΔH) for the reaction: H2(g) + 1/2 O2(g) → H2O(l) if the standard enthalpy of formation of H2O(l) is -285.8 kJ/mol?

Options:

1. -285.8 kJ/mol
2. 285.8 kJ/mol
3. 0 kJ/mol
4. 571.6 kJ/mol

Correct Answer: -285.8 kJ/mol

Solution:

The change in enthalpy for the reaction is equal to the standard enthalpy of formation of H2O(l), which is -285.8 kJ/mol.