Problem Page A major component of gasoline is octane. When octane is burned in air, it chemically reacts with oxygen gas to produce carbon dioxide and water. What mass of water is produced by the reaction of of octane

Answer: The mass of the products will depend on the amount (in mols) of the reactants.

Explanation: The chemical equation for the combustion of octane (C8H18) in oxygen is:

2 C8H18 + 25 O2 - --> 16 CO2 + 18 H20

This tells us that 2 molecules of octane needs to react with 25 oxygen molecules, and will produce 16 carbon dioxide molecules and 18 water molecules.

You will need to calculate the number of molecules using the sample mass and molar mass for each compound, or vice versa.

For this basic form of the reaction, to calculate the mass of the water produced, first calculate the molar mass of H20:

H has a molar mass of 1 and there are two: 2x1

O has a molar mass of 16

The molar mass of H2O is 2x1 + 16 = 18, so each molecule has a molar mass of 18.

But 18 molecules are produced, so 18x18 = 324 for the most basic form of the reaction.