DENSITY
What’s Density?
Tell me everything you think
you know about Density? Try!!!
Let’s talk about Density
What’s more dense…a bowling ball or a
volley ball of equal size?
The bowling ball of course! But why?
Because it has more particles squeezed in
the same amount of space!
*Density is…
a physical property that describes how
much matter is packed in a given space
(volume).
Let’s Talk About Density…
Do you remember what the density of
water is from 7th grade?
Density of water is 1 g/cm3
It is measured by taking the mass per
volume ratio.
In other words divide the mass by the
volume.
Mass
*Density =
Volume
Remember…
Mass = how much matter is in an object.
Volume = how much space an object
takes up.
Remember what weight is?
Weight is how much gravity is pulling on
an objects mass!
DENSITY
Let’s talk about units for a minute…
For mass: kg, g, mg
For volume: cm3, L, mL
Why is cm cubed (to the 3rd power)?
Because cm3 = length x width x height
1cm3 = 1ml or… cc = cubic centimeter
For Density: g/cm3 or kg/ml or mg/cc or kg/cm3
*Recognizing Units
Copy down all 10 examples and determine if they are
density, mass or volume?
1. 43 g/cm3
2. 800 kg
3. 456 cm3
4. 77 mg/cc
5. 762 ml
6. 67 mg
7. 31 g/liter
8. 212 g
9. 100 cc
10. 67 mg/ml
1. Density
2. Mass
3. Volume
4. Density
5. Volume
6. Mass
7. Density
8. Mass
9. volume
10. Density
So this is…
DUFAS
and…
This is how we will solve ALL
our word problems!!!
How DUFAS works…
All problems will be worth 5 points.
You will get 1 point for every DUFAS
step.
So…correct answers are only worth 1
point!
DUFAS
• D is for Data
(Write down all the important Data in the problem)
• U is for Units
(Write down all the units in the problem)
• F is for Formula
(set up the correct formula)
• A is for arrange the formula
(re-arrange it if you have to and plug in numbers)
• S is for Solve the problem
DATA:
Copy this Example: Ashley’s 2.4 cm3 ear ring has a
density of 19.3 g/cm3. What is the earing’s mass?
What is the important Data in this question?
V = 2.4 cm3
D = 19.3 g/cm3
What are we looking to solve for here?
m=?g
UNITS:
Example: Ashley’s 2.4 cm3 ear ring has a
density of 19.3 g/cm3. What is it’s mass?
Write down all the CORRECT UNITS in this
problem!!!
V = cm3
D = g/cm3
m=?
FORMULA:
Example: Ashley’s 2.4 cm3 ear ring has a
density of 19.3 g/cm3. What is it’s mass?
You must write the formula for EVERY problem.
*The Power Triangle will help you to do this!
Draw a triangle like this one!
How to use the Power Triangle
What is the formula for Density? = m
v
So how do we set up the power triangle?
So what is the formula for volume? m
D
*What about mass?
DxV
Arrange:
Example: Ashley’s 2.4 cm3 ear ring has a
density of 19.3 g/cm3. What is it’s mass?
New Formula is M=D x V
D= 19.3 g/cm3
V= 2.4 cm3
m=(19.3 g/cm3) x (2.4 cm3)
Solve:
Now you need to substitute the data into the
arranged formula to SOLVE.
m=D*V
m =(19.3 g/cm3)*(2.4 cm3)
V = 2.4 cm3
D = 19.3 g/cm3
m=?g
m = 46.32 g
What happened to the cm3?
They canceled each other out!
*Lets Practice using DUFAS!
1.) A 42.6 g gold ring has a density of 19.3 g/cm3.
How much space is it taking up?
*Lets Practice using DUFAS!
1.) A 42.6 g gold ring has a density of 19.3 g/cm3.
How much space is it taking up?
2.) A 257.8 cm3 man has a density of 11 kg/cm3.
What is his mass?
3.) What is the density of a 52.1 cm3 block of ice
that has a mass of 47.93 g?
*Lets Practice using DUFAS!
2.) A 257.8 cm3 man has a density of 11 kg/cm3.
What is his mass?
*Lets Practice using DUFAS!
3.) What is the density of a 52.1 cm3 block of ice
that has a mass of 47.93 g?
Practice Answers
1.) m = 42.6 g
d = 19.3 g/cm3
v = ? cm3
v=m
D
D=m
v
v = 42.6 g
= 2.20 cm3
19.3 g/cm3
Practice Answers
2.) m = ? kg
d = 11 kg/cm3
v = 257.8 cm3
m= v*D
D=m
v
m = 257.8 cm3 * 11 kg/cm3
= 2835.8 kg
Practice Answers
3.) m = 47.93 g
d = ? g/cm3
v = 52.1 cm3
D=m
v
D = 47.93 g
52.1 cm3
.91 g/cm3
Density Calculations
1. 2260 g
2. 1 g/cc
3. 0.79 g/L
4. 680 cm3
5. 16.25 cc
6. 64.8 g
7. 204 g
8. 0.000084 g/cc
9. 58 cm3
10. 90.1 g
11. 25 cm3
12. 4.9 g/ml
13. 0.00017 g/cc
14. 736 g
15. 100 cc
16. 1950 g
17. 1600 g/L
18. 1284 kg
19. 20 cm3
20. 13.6 g/cc
The
Density
Column
Lab
Using Density to Predict Position
*If we put a solid into a liquid, and the
solid is more dense than the liquid it
will sink
*If the liquid is more dense then the
solid will Float
*The same thing goes for all liquids.
The least dense floats on top of more
dense.
Question…
If the lead weight is dropped into the
beaker of water… will it sink or float?
d= 11.4 g/ml
What will happen if it is dropped into
the mercury?
ALL solids have the same volume of 15.6 ml
Masses:
pine = 5.4g acrylic = 17.3g steel = 128.5g
wax = 9.8g
pvc = 13.7g
Draw the density column (in the middle)
with it’s densities (on left side)
Calculate the
densities of
the five
substances
and predict
where they
would sink to
in the density
column.
Take two
places past
the decimal.
ALL solids have the same volume of 15.6 ml
Masses:
pine = 5.4g acrylic = 17.3g steel = 128.5g
wax = 9.8g pvc = 13.7g
Explain what happens to the mass,
volume and density of Aluminum foil
when it is crumpled up?
Will it increase, decrease or stay the same?
1.The Mass will…
2. The Volume will…
3. The Density will…
Explain why it will increase decrease or
stay the same in a sentence or two.
Mass
1. The mass will stay the same!
Due to law of conservation of mass!
Volume
2. Volume will decrease b/c it is
getting smaller.
Density
3. The density will increase.
More mass squeezed in a smaller
space.
Density 101
1. A gold-colored ring has a volume of 1.12 ml
and a mass of 18.9 grams. Is the ring pure
gold? (The density of pure gold is 19.3 g/ml.)
D= M/V
Density= 16.87 g/ml
No it is not pure gold. It’s less dense than gold.
Density 101
2. What volume would a 0.871 gram
sample of air occupy if the density of
air is 1.29 g/liter?
V= M/D
.67 liters
Density 101
3. Pumice is volcanic rock that contains many
trapped air bubbles. A 225 gram sample
occupied 236.6 ml. What is the density of
pumice?
.95 g/ml
3a. What’s the density of water?
1 g/cm3 or 1 g/ml
3b. Will pumice float on water?
Yes, pumice will float on water b/c it is less dense.
Volcanic Rock
Pumice
Pumice in Water
Density 101
4. A cup of sugar has a volume of 237 ml.
What is the mass of the cup of sugar if the
density is 1.59 g/ml?
M= D x V
M= 376.83 g
Density Review
use DUFAS to solve
1. A student finds a rock on the way to school. In
the laboratory he determines that the rock takes
up 22.7 mL of space, and has a mass of 39.943
g. What is the density of the rock?
D= M/V 1.75 g/ml
2. The density of silver is 10.49 g/cm3. If a sample
of pure silver has a volume of 12.993 cm3, what is
the mass?
M= DxV 136.29 g
3. A screwdriver has the density of 5.5 grams per
cubic centimeter. It also has the mass of 2.3g.
How much space does the screwdriver take up?
V=M/D .41 cm3
*Density Practice DUFAS Problems
Spectrum Text page 56 (1-2, 6-9)
1.Density of tin 7.30g/cm3
2. 3.26 g/cm3
3. 1.4 x 10-4 g/cm3 (gas)
4. 11.30 g/cm3 (Lead)
5. 0.670 g/cm3
6. 512 grams
7. 400 grams
8. 36 cm3
9. 0.029 cm3
Density Calculations
1. 2260 g
2. 1 g/cc
3. 0.79 g/L
4. 680 cm3
5. 16.25 cc
6. 64.8 g
7. 204 g
8. 0.000084 g/cc
9. 58 cm3
10. 90.1 g
11. 25 cm3
12. 4.9 g/ml
13. 0.00017 g/cc
14. 736 g
15. 100 cc
16. 1950 g
17. 1600 g/L
18. 1284 kg
19. 20 cm3
20. 13.6 g/cc