Question

Ethanol, C2H5OH, is mixed with gasoline and sold as gasohol. Use the following information to calculate the grams of ethanol needed to provide 658 KJ of heat:

C2H5OH(l)+ 3O2(g)---> 2CO2(g)+ 3H2O(g); (delta) H= -1235 KJ

Answer 1

Ethanol, C2H5OH, is mixed with gasoline and sold as gasohol. Use the following information to calculate the grams of ethanol needed to provide 658 KJ of heat:

C2H5OH(l)+ 3O2(g)---> 2CO2(g)+ 3H2O(g); (delta) H= -1235 KJ

Given :

Delta H of this reaction = - 1235 kJ

Lets find moles of ethanol

From reaction we say that 1 mol ethanol gives – 1235 kJ heat

So we calculate moles of ethanol by using given heat

Moles of ethanol = 658 kJ x 1 mol / 1235 kJ = 0.533 mol

Mass in g = moles x molar mass

Mass of ethanol in g = 0.533 mol x 46.068 g /mol

= 24.54 g