# Question #ba9ef

##### 1 Answer

#### Explanation:

The idea here is that you need to use the density of the solution to find the *mass* of a sample of known *volume*.

As you know, the **molarity** of a solution tells you the number of moles of solute present for every

In your case, a **moles** of potassium oxalate **for every**

To make the calculations easier, let's pick a sample of this solution that has a volume of **moles** of potassium oxalate.

Use the **molar mass** of potassium oxalate to convert the number of moles to *grams*

#0.220 color(red)(cancel(color(black)("moles K"_2"C"_2"O"_4))) * "166.22 g"/(1color(red)(cancel(color(black)("mole K"_2"C"_2"O"_4)))) = "36.57 g"#

Now, you know that this solution has a **density** of **every**

Consequently, this particular sample will have a mass of

#10^3 color(red)(cancel(color(black)("mL solution"))) * "1.0235 g"/(1color(red)(cancel(color(black)("mL solution")))) = "1023.5 g"#

You know no the **total mass** of the solution and the mass of potassium oxalate it contains, so you can say that the **mass fraction** of the solute will be

#(36.57 color(red)(cancel(color(black)("g"))))/(1023.5color(red)(cancel(color(black)("g")))) = color(darkgreen)(ul(color(black)(0.0357)))#

The answer is rounded to three **sig figs**, the number of sig figs you have for the molarity of the solution.