Electric generating plants transport large amounts of water through metal pipes, and oxygen dissolved in the water can cause a major corrosion problem. Hydrazine (N2H4) added to the water avoids the problem by reacting with the oxygen:
N2H4(aq) + O2(g) → N2(g) + 2 H2O(l)
About 4x10^7 kg of hydrazine is produced every year by reacting ammonia with sodium hypochlorite in the Raschig process:
2 NH3(aq) + NaOCl(aq) → N2H4(aq) + H2O(l) Δh degrees =-151 kJ
a) If ΔHf of NaOCl(aq) =-346 kJ/mol, find ΔHf of N2H4(aq).