Question

4 mg of zinc found in 100g of oysters what is the ppm?

Answer 1

`"40 ppm"`

Explanation:

Very small concentrations are usually expressed in parts per million, which denote one part solute per one million parts solution.

In other words, if you take the ratio between the mass of the solute and the mass of the solution, both expressed in grams, and multiply it by `10^6`, you get the cocnentration in ppm.

This is exactly how you would get percent concentration, the only difference beingthat you need to multiply that ratio by `10^2`, not by `10^6` like you need for ppm concentration.

So, your concentration in ppm is

`(4 * 10^(-3)color(red)(cancel(color(black)("g"))))/(1 * 10^2color(red)(cancel(color(black)("g")))) * 10^6 = 4 * 10^1 = color(green)("40 ppm")`