# Question 15270

Jun 30, 2015

To solve this problem you need to use the formula for density.

#### Explanation:

Density is defined as mass per unit of volume.

Mathematically, the relationship between density, mass, and volume can be written like this

$\rho = \frac{m}{V}$

In your case, you know that ether has a density of 0.71 g/mL. This means that every mL of ether has a mass of 0.71 g. Likewise, you can say that every 0.71 g of ehter occupy a volume of 1 mL.

Thus, the 250-g sample will have a volume of

250cancel("g") * "1 mL"/(0.71cancel("g")) = "352.1 mL"

Rounded to two sig figs, the answer will be

V_"ether" = color(green)("350 mL")

Now for the mass of the urine sample. The density of urine in a patient with kidney malfunction is known to be 1.001 g/mL.

This means that every mL of urine has a mass of 1.001 g. Since you have 20 mL in your sample, you'd get

20cancel("mL") * "1.001 g"/(1cancel("mL")) = "20.02 g"

Rounded to one sig fig, the number of sig figs you gave for the volume of the sample, the answer will be

m_"urine" = color(green)("20 g")#