Calculate the heat evolved when 355 g of octane burns

Question

Octane a major component of gasoline, burns according to the reaction: 2C8H18(l) + 25O2(g) ----------> 16 CO2(g) + 18H2O(g) ^H = -1.10 x 10^4 kJ Calculate the heat evolved when 355 g of octane burns

additional instruction: answer should be round off to the nearest whole number. don't specify the unit of measurement

Answer 1

2C8H18(l) + 25 O2(g) ----------> 16 CO2(g) + 18H2O(g) ^H = -1.10 x 10^4 kJ

This is the same type problem as the last one you posted, and we'll do it the same way.

molar mass C8H18 = 114.2 g /mole

355 g C8H18 x 1 mol / 114.2 g = 3.11 moles

3.11 moles x -1.10x10⁴ kJ / 2 moles = -1.71x10⁴ kJ

Answer = -1.17x10⁴ = -11700