Answer : 42 grams of oxygen are required.
Explanation :
Step 1 : Write balanced chemical equation.
The combustion reaction of octane with oxygen can be written as,
Step 2 : Find moles of octane.
The given mass of octane is 12 g
Molar mass of octane is 114.2 g/mol
The moles of octane are calculated as,
We have 0.105 mol octane.
Step 3: Use mole ratio from balanced equation to find moles of O₂
The mole ratio of octane and O₂ is 2 : 25. Let us use this as a conversion factor.
We have 1.31 mol O₂.
Step 4 : Convert moles of O₂ to grams.
The molar mass of O₂ is 32 g/mol.
The grams of O₂ can be calculated as,
42 grams of oxygen are required.