Answer:
We need 7.504 L of O2
Explanation:
Step 1: Data given
Volume of gasoline = 3.78 L
Density of gasoline = 0.81 g/mL
Molar mass octane = 114.23 g/mol
Step 2: The balanced equation
2C8H18 + 25O2 → 16CO2 + 18H2O
Step 3: Calculate mass of gasoline
Density = mass / volume
Mass = density * volume
Mass octane = 0.81 g/mL * 3.78 L
Mass octane = 3.0618 grams
Step 4: Calculate moles octane
Moles octane = mass octane / molar mass
Moles octane = 3.0618 grams / 114.23 g/mol
Moles octane = 0.0268 moles
Step 5: Calculate moles of O2
For 2 moles octane we need 25 moles O2 to produce 16 moles CO2 and 18 moles H2O
For 0.0268 moles octane we need 12.5 * 0.0268 = 0.335 moles O2
Step 6: Calculate volume O2
1 mol = 22.4 L
0.335 moles O2 = 0.335 * 22.4 L = 7.504 L
We need 7.504 L of O2