C3H4(g)+4O2(g)->3CO2(g)+2H2O(v). a) Calculate the heat of combustion per mole of C3H4 if the standard enthalpy of formation of gaseous propyne is +134.5 kJ/mol (continued in desc)

Question

b) Calculate the heat evolved upon combustion of one kilogram of C3H4.



H2O heat of formation: -241.8 kJ/mol

CO2 heat of formation: -393.5 kJ/mol

PLEASE USE SIG FIGS!!!!

Answer 1

C₃H₄ + 4O₂ ==> 3CO₂ + 2H₂O

a). Heat of combustion

Heat of rxn = ∑∆Hf _products - ∑∆Hf_reactants

∆Hºrxn = (3 * -393.5 + 2 * -241.8) - (134.5 + 0)

∆Hºrxn = (-1180.5 + -482) - 134.5

∆Hºrxn = -1662.5 - 134.5

∆Hºrxn -1797 kJ/mol

b). Heat produced from 1 kg C₃H₄

molar mass C₃H₄ = 40.065 g / mol

1 kg x 1000 g / kg x 1 mol / 40.065 g = 24.959 mols C₃H₄

∆H = 24.959 mols x -1797 kJ/mol = 44,852 kJ = 44,850 kJ