# Question #91ed4

##### 1 Answer

Here's what I got.

#### Explanation:

Assuming that you're supposed to calculate the solution's **percent concentration by mass**, *mass*.

The solution is said to have a density of **every milliliter** of this solution has a mass of

Your sample will thus have a mass of

#5.00 * 10^2color(red)(cancel(color(black)("mL"))) * "1.12 g"/(1color(red)(cancel(color(black)("mL")))) = "560 g"#

Now, the solution's percent concentration by mass tells you how much solute, which in your case is sodium chloride, **for every**

Since you know that

#100 color(red)(cancel(color(black)("g solution"))) * "21.0 g NaCl"/(560color(red)(cancel(color(black)("g solution")))) = "3.75 g NaCl"#

This means that the solution has a percent concentration by mass equal to

#color(green)(bar(ul(|color(white)(a/a)color(black)("% m/m " = " 3.75% NaCl")color(white)(a/a)|)))#

The answer is rounded to three **sig figs**.

**SIDE NOTE** *At room temperature, a sodium chloride solution of density equal to* *has a percent concentration by mass of about* *so make sure to let me know if this is not the correct interpretation of the problem.*