Question

Calculate the enthalpy of oxidation per mole for N₂ and for C₂H₂ (the enthalpy of formation of N₂O₅(g) is 11.30 kJ/mol).

Answer 1

Solution :-

The reaction equation for the N2 is as follows

N2(g) + 5O2 (g) ------ > 2N2O5(g)

Delta H reaction = sum of delta Hf product – sum of deltaHf reactant

                              = [(N2*1)+(O2*5)] – [N2O5 * 2]

                              = [(0*1)+(0*5)] – [11.30 *2 ]

                              = -22.6 kJ

For 1 mol it is calculalted as

-22.6 kJ / 2 mol N2 = -11.30 kJ/mol

So the enthalpy of oxidation of 1 mol N2 is -11.30 kJ/mol

Part 2) balanced reaction equation for the C2H2 is as follows

2C2H2(g) + 5O2(g) -----> 4CO2(g) + 2H2O(g)

Delta H rxn = sum of delta Hf product - sum of delta Hf reactant

                     = [(CO2*4)+(H2O*2)] – [C2H2*2]

                     = [(-393.5 *4)+(-241.8*2)] – [ 227*2]

                     = -2512 kJ

For 1 mole C2H2 enthalpy oxidation is = -2512 kJ / 2 mol = -1256 kJ/mol