Measuring Matter Topic 2 Lesson 2

Units of Mass

■ International System of

Units (SI) – A system of
measurement based on
multiples of ten and on
established measures of
mass, length, and time. For
mass, the SI unit is the
kilogram (kg).

Volume

■ Volume – the amount of space that matter

occupies.

■ The SI unit for volume for liquids is the Liter

(L) of Milliliter (mL).

■ Volume of Solids

■ in the SI unit is
measured in cubic
meters (m, cubic
centimeters, or
cubic millimeters

Density

■ Density – the measurement of how much mass is contained in a

given volume.

■ The SI unit for density of a liquid g/mL.

■ The SI unit for a solid can be expressed in grams in one cubic

centimeter (g/cm3)

■ To calculate the density of an object, divide its mass by its

volume.

Sample Problem

A small block of wood floats on water. It has a volume
of 25 cubic centimeters and a mass of 20 grams. What
is the density of the wood?

Analyze – you know the mass and volume. You want to
find the density.
Write the formula.

Density = Mass

Volume

Substitute and solve. Density = 20g

25 cm3

Density = 0.8 g/cm3

Think about it. The answer shows mass per unit
volume. The correct unit is g/cm3.

Practice Problem #1

■A sample of liquid has a mass of 24 grams and a volume of 16
milliliters. What is the density of the liquid?

■Analyze – You know the mass and volume. You want to find
the density.

■A sample of liquid has a mass of 24 grams and a volume of 16
milliliters. What is the density of the liquid?

■Analyze – You know the mass and volume. You want to find
the density.

■Write the formula.

Density = Mass

Volume

■Substitute and solve.

Density = 24g

16 mL

■

Density = 1.5 g/mL

■Think about it. The answer shows mass per unit volume. The
correct unit is g/mL .

Practice Problem #2

■ A metal sample has a mass of 43.5 grams and a volume

of 15 cubic centimeters (cc). What is its density?

■ A metal sample has a mass of 43.5 grams and a

volume of 15 cubic centimeters (cc). What is its
density?

■ Analyze – You know the mass and volume. You want to

find the density.

■ Write the formula.

Density = Mass

Volume

■ Substitute and solve.Density = 43.5 g

15 cc

■
Density = 2.9 g/cc

■ Think about it.1 cm3 = 1 mL = 1 cc