# Question c4bb4

Jun 7, 2015

The mass of propylene glycol will be equal to 69.4 g.

A substance's density is defined as mass per unit of volume. If you're dealing with grams and mililiters, a substance's density will tell you two things

• What the mass of 1 mL of that substance is;
• What the volume of 1 g of that substance is.

Propylene glycol has a density of 1.036 g/mL at ${25}^{\circ} \text{C}$. You can write this as

$\rho = \text{1.036 g"/"1 mL}$

This means that every mililiter of propylene glycol has a mass of 1.036 g. Subsequently, you get

$\frac{1}{\rho} = \text{1 mL"/"1.036 g" = "0.9653 mL"/"1 g}$

This means that each gram of propylene glycol occupies a volume of 0.9653 mL.

Since you have 67.0 mL, the mass of the sample will be

$67.0 \cancel{\text{mL") * "1.036 g"/(cancel("mL")) = color(green)("69.4 g}}$

For example, if they give 67.0 g of propylene glycol, and ask you what volume the sample occupies, you can use

67.0cancel("g") * "1 mL"/(1.036cancel("g")) = "64.7 g"#