How much energy in kilocalories is emitted by Dr the complete combustion of 386 g of isooctane (C8H18)? (ΔHrxn = - 36 kJ/g C8H18)

Question

How much energy in kilocalories is emitted by Dr the complete combustion of 386 g of isooctane (C8H18)?

(ΔHrxn = - 36 kJ/g C8H18)

Answer 1

2C₈H₁₈ + 25O₂ ==> 16CO₂ + 18H₂O ... balanced equation for complete combustion of C₈H₁₈

∆H_rxn = -36 kJ/g C₈H₁₈

386 g C₈H₁₈ x -36 kJ /g = -13,896 kJ

Converting kJ to kilocalories, we have ...

-13,896 kJ x 1 kcal / 4.184 kJ = -3321 kcal