Chapter 1

Density

Measuring Volume

• The amount of space occupied by an object is called its volume

• If you want to know the volume of a solid rectangle, such as a brick, you measure its length, width, and, height and multiply the three numbers and their units together (V = 1 x w x h).

Measuring Volume • For a brick, your measurements

probably would be in centimeters. • The volume would then be

expressed in cubic centimeters, cm3.• In measuring a liquid’s volume, you

are indicating the capacity of the container that holds that amount of liquid.

• The most common units for expressing liquid volumes are liters and milliliters.

Measuring Liquid Volume

• A liter occupies the same volume as a cubic decimeter, dm3.

• A cubic decimeter is a cube that is 1 dm, or 10cm, on each side.

Measuring Matter

• Mass is a measurement of the quantity of matter in an object.

• Density of a material does not change even if the shape of the object does because it is still the same material. It still has the same “stuff” in it.

Density

• The mass and volume of an object can be used to find the density of the material the object is made of.

• Density is the mass per unit volume of a material.

• You find density by dividing an object’s mass by the object’s volume.

Derived Units• Combination of base units.• Mass-Base unit: kilograms (kg) Grams (g) and

milligrams (mg) are used for measuring objects of small mass.

• Volume - length width height 1 cm3 = 1 mL 1 dm3 = 1 L

• Density - mass per unit volume (g/cm3)

D =

MV D

MV

Density• An object has a volume of 825 cm3

and a density of 13.6 g/cm3. Find its mass.

GIVEN:

V = 825 cm3

D = 13.6 g/cm3

M = ?

WORK:M = DV

M = (13.6 g/cm3)(825cm3)

M = 11,220 gDMV

Density1) A liquid has a density of 0.87 g/mL.

What volume is occupied by 25 g of the liquid?

GIVEN:

D = 0.87 g/mLV = ?M = 25 g

DMV

WORK:V = M D

V = 25 g

0.87 g/mL

V = 28.7 mL

Density2) You have a sample with a mass of

620 g & a volume of 753 cm3. Find density.

GIVEN:

M = 620 gV = 753 cm3

D = ?

DMV

WORK:D = M V

D = 620 g

753 cm3

D = 0.82 g/cm3

Liquid Layers• Look at the picture of a

variety of liquids. Which layer has the highest density?

• Which layer has the lowest density?

• Imagine that the liquids have the following densities: – 10g/cm3. 3g/cm3.– 6g/cm3. 5g/cm3.

• Which number would go with which layer?