Question

Problem 9.7 Heats of Reaction Use tabulated heats of formation to determine the standard heats of the following reactions in kj, letting the stoichiometric coefficent of the first reactant in each reaction equal one. Physical Property Tables Oxidation of Nitrogen Nitrogen (N2) and oxygen (O2) react to form nitrogen tetraoxide. AH, kJ the tolerance is +/-2%

Answer 1

1. N2 +2 02 N204 1 mol of N2 requires 2 mol of oxygen and produces 1 mol of N204 Heat of formation of N2=0 KJ/mol Heat of formation of O2=0 KJ/mol Heat of formation of N204=9.16 KJ/mol Heat of reaction=Heat of formation of N204*Mole of N204-Heat of formation of N2*Mole of N2-Heat of formation of O2*Mole of O2 Heat of reaction=1 mol*9.16 KJ/mol-1 mol*0 KJ/mol-2*0 KJ/mol Heat of reaction=9.16 KJ 2. C5H12+5.5 02 5 CO+ 6 H2O 1 mol of C5H12 requires 5.5 mol of O2 and produces 5 mol of Co and 6 mol of water Heat of formation of C5H12 (g) =-146.8 KJ/mol Heat of formation of O2=0 KJ/mol Heat of formation of CO=-110.5 KJ/mol Heat of formation of H2O (L) =-285.83 KJ/mol Heat of reaction= Heat of formation of CO*Mole of CO +Heat of formation of H2O*Mole of H20-Heat of formation of C5H12*Mole of C5H12-Heat of formation of O2*Mole of O2 Heat of reaction=5 mol*(-110.5 KJ/mol) + mol*(-285.83 KJ/mol)-5.5 mo1*0 KJ/mol-1 mol*(-146.8 KJ/mol) Heat of reaction=-2120.68 KJ|

3. C6H14+ 6.5 02 6 CO + 7 H2O 1 mol of C6H14 requires 6.5 mol of O2 and produces 6 mol of CO and mol of water Heat of formation of C6H14 (1) =-198.7 KJ/mol Heat of formation of O2=0 KJ/mol Heat of formation of CO=-110.5 KJ/mol Heat of formation of H20 (g) =-241.82 KJ/mol Heat of reaction=Heat of formation of CO*Mole of CO +Heat of formation of H2O*Mole of H2O-Heat of formation of C6H14*Mole of C6H14-Heat of formation of O2*Mole of O2 Heat of reaction=6 mol*(-110.5 KJ/mol) +7 mol*(-241.82 KJ/mol)-6.5 mol*o | KJ/mol-1 mol*(-198.7 KJ/mol)=-2157.04 KJ 4. Na2SO4 (S) + 2 C(S) 2 CO2 (G)+ Na2S (L) 1 mol of Na2SO4 requires2 mol of Cand produces 2 mol of CO2 and 1 mol of Na2S Heat of formation of Na2SO4=-1387.1 KJ/mol Heat of formation of C=0 KJ/mol Heat of formation of CO2=-393.5 KJ/mol Heat of formation of Na2S=-369 KJ/mol Heat of reaction= Heat of formation of Na2S*Mole of Na2S +Heat of formation of CO2*Mole of CO2-Heat of formation of Na2SO4*Mole of Na2SO4-Heat of formation of C*Mole of C Heat of reaction=1 mol*(-369 KJ/mol) + 2 mol*(-393.5 KJ/mol) - 1 mol *(- 1387.1 KJ/mol)-2 mol*0 KJ/mol=231.1 KJ