Carbon, hydrogen and ethane each burn exothermically in an excess of air. 1. c(s)+o2(b) co2(g) ah-393.7 kl mol h2(g) +o2(g) h20(i) ah-285.9 kj mol chalg)+302(b)2co2(g) + 2h 20 ( ) ah-1411.0 kj mol use the data to calculate the standard enthalpy change of formation, ah, in kj mol, of ethene at 298 k. 2c(s)+2h2(b) cahalb) 2. manganese metal can be obtained by the reaction of manganese dioxide with aluminium. 4al(s)+3mno2(s)2 al, os(s)+3 mn(s) calculate the enthalpy change of reaction. given: 2al(s)+3/2 02(g) al2os(s) ah-1680 kj mol. mn(s)+o2(g) mno2 (s) ah -520 kj mol1