Solving for a reactant using a chemical equation

Question

A major component of gasoline is octane (C8H18). When octane is burned in air, it chemically reacts with oxygen gas (O2) to produce carbon dioxide (CO2) and water (H2O) .

What mass of carbon dioxide is produced by the reaction of 9.6 g of octane?

Be sure your answer has the correct number of significant digits.

Answer 1

Write a balanced equation:

2C8H18 + 25O2 => 16CO2 + 18H2O .. balanced eq

Molar mass C8H18 = 114 g/ mole

moles of C8H18 used = 9.6 g x 1 mol/114 g = 0.0842 moles

moles CO2 produced = 0.0842 mols C8H18 x 16 mol CO2/2 mol C8H18 = 0.674 mol CO2

mass CO2 = 0.674 mol CO2 x 44 g/mole = 29.6 g CO2 = 30.g CO2 (2 sig. figs )