posted by Tanisha .
If 23.7g of C8H18 are combusted, what mass of water will be produced?
First establish the combustion equation and have it balanced:
C8H18 + O2 -> 8CO2 + 9H2O.
Balances for C, but not for O.
Since there are 16+9=25O on the right, we need to double the number to make the number of molecules on the left a whole number. So it becomes:
2C8H18 + 25O2 -> 16CO2 + 18H2O.
Next step is to observe the relative molecular masses in 8H18 and 18H2O.
You can then calculate the mass of H2O produced by proportions using 23.7g of octane.