Question

Determine the standard enthalpy change for the formation of water (H2O) when hydrogen gas (H2) reacts with oxygen gas (O2) according to the balanced equation:2H2(g) + O2(g) → 2H2O(l)Given that the standard enthalpy change of formation for H2O(l) is -285.8 kJ/mol, calculate the amount of heat absorbed or released when 4.50 moles of H2O(l) is formed under standard conditions.

Answer 1

To calculate the amount of heat absorbed or released when 4.50 moles of H2O l  is formed under standard conditions, we can use the following equation:q = n  Hfwhere q is the heat absorbed or released, n is the number of moles, and Hf is the standard enthalpy change of formation.Given that the standard enthalpy change of formation for H2O l  is -285.8 kJ/mol, and we want to find the heat absorbed or released when 4.50 moles of H2O l  is formed:q =  4.50 moles    -285.8 kJ/mol q = -1286.1 kJSince the value is negative, it means that the reaction is exothermic, and 1286.1 kJ of heat is released when 4.50 moles of H2O l  is formed under standard conditions.