1) Consider the reaction : N2 + 3H2 → 2NH3 carried out at constant temperature and pressure. If ΔH and ΔU are the enthalpy and internal energy changes for the reaction, which of the following expressions is true ? A) $\triangle H>\triangle U$ B) $\triangle H<\triangle U$ C) $\triangle H=\triangle U$ D) $\triangle H=0$ Answer: Option BExplanation:ΔH = ΔU + ΔnRT for N2 + 3H2 → 2NH3 Δng = 2 - 4 = -2 .'. ΔH = ΔU - 2RT or ΔU = ΔH+2RT .'. ΔU > ΔH
