Question

What is the standard enthalpy change (∆H°f) for the formation of methane gas (CH4) from its elements in their standard states at 298 K? C (s) + 2H2 (g) → CH4 (g) Given Data: ∆H°f (kJ/mol) C (s) = 0 H2 (g) = 0 CH4 (g) = -74.8

Answer 1

The standard enthalpy change  Hf  for the formation of methane gas  CH4  from its elements in their standard states at 298 K is already given in the problem:Hf  CH4, g  = -74.8 kJ/molThis value represents the enthalpy change when one mole of methane gas is formed from its elements  carbon and hydrogen  in their standard states at 298 K.