1. Density Notes

2. A. A kilogram of feathers
Which has more mass?
A. A kilogram of feathers OR
B. A kilogram of bricks

3. A. A kilogram of feathers
Which has more mass?
A. A kilogram of feathers OR
B. A kilogram of bricks
ANSWER: Both a kilogram of feathers and bricks have the same mass.

4. Which would take up more volume?
A kilogram of feathers OR
B. A kilogram of bricks

5. Which would take up more volume?
A kilogram of feathers OR
B. A kilogram of bricks
ANSWER: A kilogram of feathers has more volume because of the differences in density between feathers and bricks.

6. Density
Density is the measurement of how much mass is contained in a given volume.

7. The following pictures show an increase in density from left to right
The following pictures show an increase in density from left to right. As the mass increases in a given volume the density increases.
Most Dense
Least Dense

8. Calculating Density
Density is calculated by dividing a substances mass by its volume.
Density = Mass  Volume

9. Units of Density
The unit for density is always a unit of mass, such as grams, over a unit of volume, such as cubic centimeters or milliliters.
Units for the density of a solid
g/cm3 = grams per centimeters cubed
Units for the density of a liquid
g/mL = grams per milliliter
1g/mL = 1g/cm3

10. Density Problems There are 3 steps involved in solving this problem.
Write the formula
Substitute the known numbers
into the formula
3. Solve

11. There are 3 different formulas that could be used depending on whether the problem asks you to find the density, the mass or the volume of a substance.
Density = Mass  Volume
Volume = Mass  Density
Mass = Density  Volume

12. A quick and easy way to help you remember these formulas is to use the symbol pictured to the right.

13. How to find Density
Sample Problem: A substance has a volume of 25 cm3 and a mass of
50 grams. What is the density of the substance?
Step 1: Write the formula
Density = Mass  Volume
Step 2: Substitute the known numbers into the formula
Density = 50 g  25 cm3
Step 3: Solve (Your answer must always include the correct units)
Density = 2 g/cm3

14. Practice Question Try this one on your own
A substance has a volume of 4 cm3 and a mass of 12 grams. What is the density of the substance?
Step 1:
Step 2:
Step 3:

15. Practice Question Try this one on your own
A substance has a volume of 4 cm3 and a mass of 12 grams. What is the density of the substance?
Step 1: Density = Mass  Volume
Step 2: Density = 12 g  4 cm3
Step 3: Density = 3 g/cm3

16. How to find Volume
Sample Problem: A substance has a mass of 10 grams and a density of
2 g/cm3. What is the volume of the substance?
Step 1: Write the formula
Volume = Mass  Density
Step 2: Substitute the known numbers into the formula
Volume = 10 grams  2 g/cm3
Step 3: Solve (Your answer must always include the correct units)
Volume = 5 cm3

17. Practice Question Try this one on your own
A substance has a density of 5 g/cm3 and a mass of 20 grams. What is the volume of the substance?
Step 1:
Step 2:
Step 3:

18. Practice Question Try this one on your own
A substance has a density of 5 g/cm3 and a mass of 20 grams. What is the volume of the substance?
Step 1: Volume = Mass  Density
Step 2: Volume = 20 grams  5 g/cm3
Step 3: Volume = 4 cm3

19. How to find Mass
Sample Problem: A substance has a volume of 100 cm3 and a density of 0.5 g/cm3. What is the mass of the substance?
Step 1: Write the formula
Mass = Density  Volume
Step 2: Substitute the known numbers into the formula
Mass = 0.5 g/cm3  100 cm3
Step 3: Solve
Mass = 50 grams

20. Practice Question
A substance has a density of 10 g/cm3 and a volume of 30 cm3. What is the mass of the substance?
Step 1:
Step 2:
Step 3:

21. Practice Question
A substance has a density of 10 g/cm3 and a volume of 30 ml. What is the mass of the substance?
Step 1: Mass = Density  Volume
Step 2: Mass = 10 g/cm3  30 ml
Step 3: Mass = 300 g

22. Floating and Sinking
It is possible to predict which objects will float and which objects will sink based on their density compared to water
Density of Water = 1g/ml

23. If an object has a density less than 1g/cm3, then it will float.
If a an object has a density greater than 1g/cm3, then it will sink.

24. Floating and Sinking Examples: Water has a density of 1.00g/mL
Lead has a density of 11.00g/cm3, therefore lead will sink
Wood has a density of 0.70g/cm3, therefore wood will float

25. Why do Ships made of Steel Float?
A solid piece of steel has a density of 7.85g/cm3, therefore it will sink

26. Why do Ships made of Steel Float?
However, when steel is crafted into the shape of a ship the density of the boat changes because you are increasing the volume.
The more the volume is increased as the mass remains the same, the less dense the object will be
That is why a ship made of steel is able to float.

27. A large volume and a relatively smaller mass results in a low density.
A small volume and a relatively larger mass results in a high density. D M M V = = D v

28. Substance
Density(g/cm3)
Glass
2.5 g/cm3
Ice
0.92 g/cm3
Cork
0.25 g/cm3
Air
Density g/cm3
Corn Oil
Density 0.9 g/cm3
Predict where the pieces of glass, ice and cork will come to rest in the density column.
Water
Density 1.00 g/cm3
Glycerine
Density 1.3 g/cm3

29. Substance
Density(g/cm3)
Glass
2.5 g/cm3
Ice
0.92 g/cm3
Cork
0.25 g/cm3
Air
Density g/cm3
Corn Oil
Density 0.9 g/cm3
Water
Density 1.00 g/cm3
Glycerine
Density 1.3 g/cm3
Glass Density
2.5 g/cm3

30. Substance
Density(g/cm3)
Glass
2.5 g/cm3
Ice
0.92 g/cm3
Cork
0.25 g/cm3
Air
Density g/cm3
Corn Oil
Density 0.9 g/cm3
Ice Density
.92 g/cm3
Water
Density 1.00 g/cm3
Glycerine
Density 1.3 g/cm3
Glass Density
2.5 g/cm3

31. Substance
Density(g/cm3)
Glass
2.5 g/cm3
Ice
0.92 g/cm3
Cork
0.25 g/cm3
Air
Density g/cm3
Cork Density
0.25 g/cm3
Corn Oil
Density 0.9 g/cm3
Ice Density
.92 g/cm3
Water
Density 1.00 g/cm3
Glycerine
Density 1.3 g/cm3
Glass Density
2.5 g/cm3

32. If a substance has its mass and volume cut in half, how does that affect its density?
The density of the substance will be greater.
The density of the substance will be less.
The density of the substance will be the same.

33. Example
If a block of metal has a mass of 100 g and a volume of 50 cm3, what is the density of the metal block?
Step 1: Density = Mass  Volume
Step 2: Density = 100 g  50 cm3
Step 3: Density = 2 g/cm3

34. If the block of metal is cut in half, what would the new mass of the metal block be?
Mass = 50g
If the block of metal is cut in half, what would the new volume of the metal block be?
Volume = 25cm3

35. If a block of metal has a mass of 50 g and a volume of 25 cm3, what is the density of the metal block?
Step 1: Density = Mass  Volume
Step 2: Density = 50 g  25 cm3
Step 3: Density = 2 g/cm3
When the metal block is cut in half, the density remains the same.

36. If a substance goes through a physical change, how does that affect its density?
The density of the substance will be greater.
The density of the substance will be less.
The density of the substance will be the same.