How many grams of oxygen are required to react with 12.0 grams of octane(c8h18) in the combustion of octane in gasoline?

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.

pure substance: iron,copper

impure substance: water,charcoal

the answer is d. 74.02