Question

Balance the chemical equation a×C8H18 + b×O2 》c×CO2 + d×H2O for the combustion reaction of octane by determining the numbers a,b,c, and d

Answer 1

For combustion equations, it is better to balance in this order

a×C8H18 + b×O2 》c×CO2 + d×H2O

C8H18 +O2 --> CO2 + H2O

balance C

C8H18 +O2 --> 8CO2 + H2O

now balance H

C8H18 +O2 --> 8CO2 + 9H2O

finally balance O

total O in right --> 8*2 + 9*1 = 16+9 = 25

so.. 25/2 = 12.5

C8H18 +25/2O2 --> 8CO2 + 9H2O

if b can't be stated as a fraction, choose 12.5

if no decimals can be stated, then multiply by 2 to get whole numbers (integers)

2 (C8H18 +25/2O2 --> 8CO2 + 9H2O)

2C8H18 +25O2 --> 16CO2 + 18H2O