chapter 5.8 density - beachwood high school 8 density.pdf · 2011-09-25 · cylinder from 25 ml to...

Chapter 5.8 Density Mrs. Baldessari

Chemistry

Objective: You will define and calculate

density with appropriate units.

1

Density

Take a look at the two boxes below. Each box

has the same volume. If each ball has the

same mass, which box would weigh more?

Why?

2

Density

Answer: The box that has more balls has more mass per unit of volume.

This property of matter is called density. The density of a material helps to distinguish it from other materials.

Density d = mass/volume (g/ml)

3

Density

Calculate the density of each block.

Block I Block II

Mass = 79.43 grams Mass = 25.41 grams

Volume=29.8 ml Volume = 29.8 ml

4

Density

Block I

– Density = 79.43 grams / 29.8 ml

= 2.67 g/ml

Block II

– Density = 25.41 grams / 29.8 ml

= 0.853 g/ml

5

6

Density units

Density compares the mass of an object to

its volume

D = mass = g or g

volume mL cm3

Note: 1 mL = 1 cm3

Density

Density is a physical characteristic of a material and allows us to determine what each block is made of.

All pieces of matter made of the same material will have the same density.

Different matter will have different densities.

7

Example #1

massDensity =

volume

3

17.8 gDensity =

2.35 cm

Density =37.57 g/cm

A certain mineral has a mass of 17.8 g and a volume of

2.35 cm3. What is the density of this mineral?

9

Example #2

massDensity =

volume

0.85 g/mL = 49.6 mL

x

mass = = 42 gx

•What is the mass of a 49.6 mL sample of a liquid, which

has a density of 0.85 g/mL?

•Cover the variable that your are

solving for

•Perform the math operation as it is

shown in the triangle

m=(D)(V)

D v

m

10

Concept Check

Copper has a density of 8.96 g/cm3. If 75.0 g

of copper is added to 50.0 mL of water in a

graduated cylinder, to what volume reading

will the water level in the cylinder rise?

a) 8.4 mL

b) 41.6 mL

c) 58.4 mL

d) 83.7 mL

11

Having trouble with the math?

m

d v

• Cover the variable

that your are solving

for

•Perform the math

operation as it is

shown in the triangle

12

Volume Displacement

A solid displaces a matching volume of water

when the solid is placed in water.

33 mL

25 mL

13

Learning Check

What is the density (g/cm3) of 48 g of a metal if the

metal raises the level of water in a graduated

cylinder from 25 mL to 33 mL?

1) 0.2 g/ cm3 2) 6 g/m3 3) 252 g/cm3

33 mL

25 mL

14

15

Solution

2) 6 g/cm3

Volume (mL) of water displaced

= 33 mL - 25 mL = 8 mL Volume of metal (cm3)

= 8 mL x 1 cm3 = 8 cm3

1 mL Density of metal = mass = 48 g = 6 g/cm3

volume 8 cm3

Learning Check

Which diagram represents the liquid layers in

the cylinder?

(K) Karo syrup (1.4 g/mL), (V) vegetable oil

(0.91 g/mL,) (W) water (1.0 g/mL)

1) 2) 3)

K

K

W

W

W

V

V

V

K

16

17

Solution

(K) Karo syrup (1.4 g/mL), (V) vegetable oil

(0.91 g/mL,) (W) water (1.0 g/mL)

1)

K

W

V

18

Density Connections

Mass Volume

kg L

g mL (cm3)

mg

Learning Check

The density of octane, a component of

gasoline, is 0.702 g/mL. What is the mass, in

kg, of 875 mL of octane?

1) 0.614 kg

2) 614 kg

3) 1.25 kg

19

20

Solution

1) 0.614 kg

Unit plan: mL g kg Equalities: 1 mL = 0.702 g and 1 kg = 1000 g Setup:

875 mL x 0.702 g x 1 kg = 0.614 kg

1 mL 1000 g

density metric

factor factor

Learning Check

If blood has a density of 1.05 g/mL, how

many liters of blood are donated if 575 g of

blood are given?

1) 0.548 L 2) 1.25 L

3) 1.83 L

21

22

Solution

1)

Unit Plan: g mL L

575 g x 1 mL x 1 L = 0.548 L

1.05 g 1000 mL

Learning Check

A group of students collected 125 empty aluminum

cans to take to the recycling center. If 21 cans

make 1.0 pound of aluminum, how many liters of

aluminum (D=2.70 g/cm3) are obtained from the

cans? Note, 1 mL = 1 cm3 1) 1.0 L 2) 2.0 L 3) 4.0 L

23

24

Solution

1) 1.0 L

125 cans x 1.0 lb x 454 g x 1 cm3

21 cans 1 lb 2.70 g

x 1 mL x 1 L = 1.0 L

1 cm3 1000 mL

25

Learning Check

You have 3 metal samples. Which one will

displace the greatest volume of water?

1 2 3

Discuss your choice with another student.

25 g Al

2.70 g/mL

45 g of gold

19.3 g/mL 75 g of Lead

11.3 g/mL

26

Solution

1) 25 g Al x 1 mL = 9.2 mL

2.70 g

25 g Al

2.70 g/mL