Given the heats of combustion of ethylene, hydrogen and ethane as 337.2, 68.3 and 372.8 kcal respectively, calculate the heat of reaction at 78°C for;
C2H4(g) + H2(g) → CH.(g)
[9 marks]​

Why is burning a log an exothermic process? a. energy must be continuously added to complete the combustion reaction. b. the log and oxygen contain more chemical energy than the gases and ash produced. c. additional energy is required to start the chemical reaction.