Question

What is the molarity if you dissolve 15 g of `FeCl_3` to make up 250 mL solution?

Answer 1

0.37 M

Explanation:

First calculate the molar mass of `FeCl_3`:

`55.85+3*35.45=162.20 g//mol`

Then calculate how many moles are 15 g of `FeCl_3`:

`color(red)(n=m/M`

`n=15/162.20=0.0925 mol`

Then calculate the concentration:

`color(red)(c=n/v`

`n=0.0925mol//0.250L=0.37 mol//L (or 0.37 M)`

The concentration is given with two representative digits which are the same ones of 15 grams.