Question

Acetylene (C2H2) undergoes combustion in excess oxygen to generate gaseous carbon dioxide and water. Given (delta)H degrees F[CO2(g)] = -393.5 kJ/mol, (delta)H degrees F[H2O(g)] = -241.8 kJ/mol, and (delta)H degrees F [C2H2(g)] = 226.6 kJ/mol, how much energy is released (kJ) when 10.5 moles of acetylene is burned?

		2.5108 MJ
		26.4 MJ
		13.2 MJ
		52.7 MJ
		9.05 MJ options listed above

Answer 1

2C2H2 (g)+ 3O2(g) -----------> 4Co2(g) +2H2O(g)

H rxn   = Hf products - Hf reactants

               = 4*-393.5+2*-241.8- (2*226.6+0)

               = -2510.8Kj

2C2H2 (g)+ 3O2(g) -----------> 4Co2(g) +2H2O(g)    H rxn   = -2510.8KJ

2 moles of C2H2 released energy is -2510.8KJ

10.5 moles of C2H2 released energy is = -2510.8*10.5/2   = -13181.7KJ   = 13.2*10^6J   = 13.2MJ >>>>>answer