You have a chapter here. It would help if you told us exactly what you don't understand. I'll get you started.
2C8H18 + 25O2 ==> 16CO2 + 18H2O + heat
or you may write it as
2C8H18 + 25O2 ==> 16CO2 + 18H2O dH = -239.5 kcal
Note that this is the reaction for the 5.00 g octane and NOT for a mol. It isn't clear from the question which you want.
During the combustion of 5.00g of octane C8H18, 239.5 kcal is released. Write a balanced equation for the combustion reaction. Are reactants or products favored? What is the sign of change of heat for this reaction? how much energy is released by the combustion of 1.53mol of C8H18? how many moles of octane must be burned to release 483.0kcal/ how many grans of octane must be burned to release 483.0kcal? How many kilocalories are released by the combustion of 18.1g of C8H18?
2 answers
The question is asking to write a balanced equation with the information given.