Ethanol, C 2 H 6 O , is most often blended with gasoline - usually as a 10 per c

Question

Ethanol, C2H6O, is most often blended with gasoline - usually as a 10 per cent mix - to create a fuel called gasohol. Ethanol is a renewable resource and ethanol-blended fuels, like gasohol, appear to burn more efficiently in combustion engines. The heat of combustion of ethanol is 326.7 kcal/mol.

The heat of combustion of 2-methylhexane, C7H16, is 1.150×103 kcal/mol. How much energy is released during the complete combustion of 323 grams of 2-methylhexane ?

Assuming the same efficiency, would 323 grams of ethanol provide more, less, or the same amount of energy as 323 grams of 2-methylhexane?

Explanation / Answer

a) heat of combustion of 2-methlhexane is 1.15x103 Kcal/mol

That is one mole (100g/Mol) of 2-methylhexane give 1.15x103 Kcal

323 g of 2-methylhexane give = 1.15x103 Kcal x323g/100g

=3.7145x103 kcal

= 3714.5 kcal

b) heat of combustion of ethanol = 326.7 kcal/mol

one mole (46g/mol) of ethanol provides 326.7 kcal

323 g of ethanol gives = 323x326.7/46 kcal

=2294.00kcal

Thus 323 g of ethanol produces less energy than 323 g of 2-methylhexane on complete combustion.

Related Questions

Navigate

• Browse (All)
• Browse E
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.