posted by Amy .
Which of the two, benzoic acid and sucrose, has the largest heat of combustion and why?
Can you look up the heats of combustion. I found -3226.9 kJ/mol for benzoic acid and -5637 kJ/mol for sucrose but you should look for yourself and confirm those numbers.
Write the combusion reaction for benzoic acid, then write the combustion reaction for sucrose. Does the reaction give you a clue as to why sucrose is greater per mole than benzoic acid?
those are the correct heat of combustions, but I am still not sure why sucrose has the larger heat of combustion.
Look up the heats of formation for CO2 and H2O. They are large. Now look at the number of mols CO2 and H2O formed by the two.23 mols combined with sucrose versus 10 mols combined for benzoic acid (per mol for each).