Question

What is the molarity of a solution that contains 50.0 g of `Mg(NO_3)_2` per 225 mL of solution?

Answer 1

`1.50 M`

Explanation:

To find the molarity, the following equation must be used:

We are given the mass and volume of the solution, but both have bad units.

The mass of `Mg(NO_3)_2` can be converted into moles by using its molar mass (148.3 g/mol) as a conversion factor:

`50.0cancelgxx(1mol)/(148.3cancelg)` `=0.337 mol`

Now we can convert 225 mL into L by multiplying 225 by 0.001 to obtain 0.225L.

All we do now is divide the number of moles by the volume to acquire the molarity:

`M = (0.337 mol) / (0.225 L)` = 1.50 M