Electric generating plants transport large amounts of hot waterthrough metal pipes, and oxygen dissolved in the water can cause amajor 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 4 x107 kg of hydrazine is produced every year byreacting ammonia with sodium hypochlorite in the Raschigprocess:
2 NH3(aq) + NaOCl(aq) →N2H4(aq) + NaCl(aq) +H2O(l) ΔrH° = −151 kJ
(a) If ΔfH°  of NaOCl(aq) =−346 kJ/mol, find ΔfH°  ofN2H4(aq) given thatΔfH° [NH3(aq)] = −80.83kJ/mol, ΔfH° [NaOCl(aq)] = −346kJ/mol, ΔfH° [Na+(aq)] =−239.66 kJ/mol, ΔfH°[Cl−(aq)] = −167.46 kJ/mol andΔfH° [H2O(l)] = −285.840kJ/mol.
______ kJ/mol
b) What is the heat released when aqueousN2H4 is added to 6.00 × 103 L ofplant water that is 2.50 × 10−4 mol/L O2?Enter your answer in scientific notation.
____× 10___ kJ
