Density Notes Test – Thursday, 11/7 Textbook & Online Resources: Chapter 8 – Lesson 1:...

Density Notes

Test – Thursday, 11/7

Textbook & Online Resources:Chapter 8 – Lesson 1: Measuring Matter

Mass

• The amount of matter in an object.

Mass

• Mass is measured in grams or kilograms.• The tools that you use for measuring mass are

a triple-beam balance or a scale.

Weight

• The force of gravity pulling down on an object.

• On planet earth, an object’s weight is the same as its mass.

Weight = 6,000 kg Mass = 6,000 kg

• However, an object’s weight can change, depending on the amount of gravity.

• Ex: weight would change in space or on another planet

Weight = 2,262 Kg Weight = 14,184 Kg

Earth = Weight = 6,000 Kg

Weight = 0 Kg

*Empty Space*

Volume

• The amount of space that is taken up by an object.

Volume

• Volume is measured in cubic centimeters (cm3) or cubic meters (m3)

• Volume of liquids is measured in milliliters (ml) or Liters (L)

Volume of a box

• Length X width X height = volume

8 cm3 cm

4 cm

8cm X 3cm X 4cm = 96 cubic centimeters

Water Displacement

• Used to find the volume of an irregular solid….like this toy dinosaur

• Measure the water level with and without the dinosaur

• ***Difference in volumes = volume of the object!

• water level with object – water level without object = volume of object

10

10

20

30

40

50

60

70

80

90

100

0

Graduated Cylinder with out marbles

1010

20

30

40

50

60

70

80

90

100

0

Cylinder with marbles

77 – 47 = 30 cm3

Density

• The formula for density is D=m/v

• OR Density = mass

volume

Don’t forget the formula for density, or you will break Mrs. Szerdy’s heart!

MV

1. If the object has a mass of 74 grams, and a volume of 8 cm3 What is the density?

• 74g/8 cm3 = 9.25 g/cm3

2. If the object has a mass of 10 grams, and a volume of 20 cm3 What is the density?

• 10g/20 cm3 = 0.5 g/cm3

The Density Formula

X

If the object has a mass of 40 grams, and a volume of 5 cm3 What is the density?

D = ???? V = 5

M = 40

X

40g/5 cm3 = 8 g/ cm3

If the object has a density of 8 g/cm3 and a volume of 5 cm3, What is the mass???

D = 8 V = 5

M = ????

X

8g/cm3 X 5 cm3 = 40 g

If the object has a mass of 40 g and a density of 8 g/cm3, what’s the volume?

D = 8 V= ????

M = 40

X

40g 8 g/cm3

= 5 cm3

3. If the object has a density of 2 g/cm3 and a volume of 10 cm3, What is the mass?

• 2 g/cm3 x 10 cm3 = 20 g

4. If the object has a density of 0.5 g/cm3 and a volume of 25 cm3, What is the mass?

• 0.5 g/cm3 x 25 cm3 = 12.5 g

5. If the object has a mass of 60 g and a density of 3 g/cm3, what’s the volume?

• 60g / 3 g/cm3 = 20 cm3

6. If the object has a mass of 150 g and a density of 5 g/cm3, what’s the volume?

• 150g / 5g/cm3 = 30 cm3

• Density is measured in grams per cubic centimeter = g/cm3

• If something has a density of 10 g/cm3, that means that 1 cm3 of the substance would weigh 10 grams.

• Density is how heavy something is in relationship to its size.

• Density Gizmo – predict float or sink

• A small object can have high density.

• Ex: a coin is heavy for its size and will sink in water.

• A small object can have low density.

• Ex: a balloon is light for its size and will float in water or air.

• A large object can have high density.

• Ex: a boulder is very heavy for its size and will sink in water.

• A large object can have low density.

• Ex: an elephant is less heavy for its size and will float in water.

• Objects with a density of less than 1 float in water

***The density of water = 1***

• Objects with a density of more than 1 sink in water

Will it float?

• Mass = 52 g• Volume = 35 cm3

52g / 35 cm3 = 1.48 g/cm3

Will it float?

• Mass = 270 g• Volume = 317 cm3

270g / 317 cm3 = 0.85 g/cm3

Will it float?

• Mass = 4 g• Volume = 10 cm3

4g / 10 cm3 = 0.4 g/cm3

• A material’s density can be used to identify it.• The density of gold is 19.3 g/cm3

• Which of the following substances is gold?

Rock AMass = 108 gVolume = 12 cm3

Rock BMass = 126 gVolume = 15 cm3

Rock CMass = 386 gVolume = 20 cm3

108g / 12 cm3 = 9 g/cm3

126g / 15 cm3 = 8.4 g/cm3

386g / 20 cm3 = 19.3 g/cm3

Find the density of these 3 pieces of gold

Small Piece of GoldMass = 386 gVolume = 20 cm3

Medium Piece of GoldMass = 1158 gVolume = 60 cm3

Large Piece of GoldMass = 5018 gVolume = 260 cm3

386g / 20 cm3 = 19.3 g/cm3

1158g / 60 cm3 = 19.3 g/cm3

5018g / 260 cm3 = 19.3 g/cm3

A material’s density is always the same! It does NOT change with its size.

• All samples of gold have the same density!!! It does not matter how large the piece is.