Question #c4bb4

1 Answer
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^@"C"#. You can write this as

#rho = "1.036 g"/"1 mL"#

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

#1/(rho) = "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

#67.0cancel("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"#