Chemistry Homework...Please Help !!! :)?

Question

Ethanol is mixed with gasoline and sold as gasahol. If the combustion of 1.00 mole of ethanol has an enthalpy of reaction of -1235 kJ, how many grams of ethanol must be burned to provide 293 kJ of heat? Provide an answer correct to 2 significant figures


Thanks in advance for your help!!!

Answer 1

Lets go through is by steps. The each mole of ethanol releases 1235kJ of energy. To release 293kJ of heat energy, 293/1235 mol of C2H5OH is needed. To get the gram, you must know the molar mass of ethanol 12x2+1x5+16+1 which is 46g/mol now times the mol by the value which comes out to be 11gram in 2s.f.

Answer 2

(293/1235) x 46