Final answer:
There are 25 grams of oil in 500 grams of a 5.0% oil (w/w) gasoline-oil mixture.
Step-by-step explanation:
To calculate how many grams of oil are in 500 g of a gasoline-oil mixture that is 5.0% oil by weight (w/w), you need to use the percent by mass formula:
Percent by mass = (mass of solute / mass of solution) × 100%
Using this formula:
5.0% = (mass of oil / 500 g) × 100%
To find the mass of oil, we can rearrange the formula:
mass of oil = (5.0/100) × 500 g
mass of oil = 0.05 × 500 g
mass of oil = 25 g