What is the density of a substance if a sample of 375 mL has a mass of 450 grams?

1 Answer
Jan 15, 2016

#"1.2 g/mL"#


As you know, density is defined as mass per unit of volume.

#color(blue)("density" = "mass"/"unit of volume")#

This means that your goal when asked to find a substance's density will be to find the mass of one unit of volume of that substance.

In your case, the sample is said to have a volume of #"275 mL"#. This means that the unit of volume will be #"1 mL"#. So, you must use the information provided to determine the mass of #"1 mL"# of your substance.

Well, you know that a volume of #"375 mL"# of this substance has a mass of #"450 g"#. Since density is essentially a measure of how the atoms that make up a substance are packed per unit of volume, you can safely assume that it will be constant for a substance as long as temperature and pressure are kept constant.

This means that you can write

#1 color(red)(cancel(color(black)("mL"))) * "450 g"/(375 color(red)(cancel(color(black)("mL")))) = "1.2 g"#

So, if #"1 mL"# of your substance has a mass of #"1.2 g"#, you can say that its density will be equal to

#"density" = rho = "1.2 g"/"1 mL" = color(green)("1.2 g/mL") -># rounded to two sig figs