1.What mass of oxygen gas, O2, from the air is consumed in the combustion of 702g of octane, C8H18, one of the principal components of gasoline? 2C8H18 + 25O2 -> 16CO2 + 18H2O.

Approximately .

Explanation:

Look up the following relative atomic mass values on a modern periodic table:

Calculate the molar mass of octane, :

.

Similarly, calculate the molar mass of :

.

How many moles of molecules in of octane, ?

.

Make sure that the chemical equation here is balanced.

In this equation,

Ratio between the two coefficients:

.

Therefore:

.

Rearrange to obtain:

.

It is already determined that . Hence, the number of moles of oxygen gas required will be:

.

What would be the mass of that of ?

.