Question

Milk fat is present in milk. Whole milk usually contains about 5.0% milk fat by volume. If I drink a glass of milk with a volume of 250 mL, what volume of milk fat have I consumed?

Answer 1

The answer is `12.5mL`.

Percent concentration by volume is defined as the volume of the solute divided by the total volume of the solution and multiplied by 100%. Mathematically, this can be written as

`c_(volume) = V_(solute)/(V_(solution)) * 100%`

Since you know that your concentration has `5%` milk fat by volume, and that the volume of the solution is `250mL`, you can determine the volume of fat from

`V_(solute) = (c_(volume) * V_(solution))/(100%) = (5.0% * 250 mL)/(100%) = 12.5mL`

This means that every 250-mL gglass of milk has `12.5mL` of fat and `250 - 12.5 = 237.5mL` of other stuff (proteins, vitamins, carbohydrates - in the form of lactose, etc).