# Question #b80d8

##### 1 Answer

Here's how you can determine the density of a *solution* if you know its molarity and its molality.

Molarity is defined as moles of **solute** per liters of **solution**.

**SIDE NOTE** *n will always represent the number of moles of solute, so I'll just leave it as n, instead of writing*

Since density is defined as mass per unit of volume, you can write the *volume of the solution* as

Use this in equation

You can write the *mass of the solution* as the sum of the mass of the **solute** and the mass of the **solvent**

Use this in equation

Now use the solution's molality, which is defined as moles of **solute** per *kilograms* of **solvent**.

Use this in equation

Assuming you know what your solute is, you can write its mass as the product between the number of moles and its molar mass

Use this in equation

As a result, the solution's density can be expressed as

Check to see if the units come out right

Convert the second term from kg per liter to grams per liter to get

And that's how you'd get the density of a solution from its molarity and molality.