Density

What is Density?

Density is a characteristic physical property of

matter

- Each substance has its own density and many substances can be identified by their densities

Densities of Some Substances

In this picture:• What is the most

dense substance?• What is the least

dense?• What 2

substances have really close densities?

What is Density?• a measure of how closely packed the particles are in

a substance

• the amount of matter a substance has in a certain space (how much mass is contained per unit of volume of a substance)

• A substance with a low density feels “light” and will float in a substance with a higher density.

•  A substance with a high density feels “heavy” and will sink in a substance with a lower density.

The equation for density is:Density (D) = Mass (m)

Volume (V)

D = m V

Density as an Equation

Solving Equations

Use GUESS method:G-given (state what you are given in the question)

U-unknown (state what you are trying to find)

E-equation (write the equation and sub numbers in)

S-substitute and solve (calculate your answer)

S-statement (write out your answer in a full sentence)

Must use this method for full marks!!!!

Calculate the density of a material that has a mass of

52.547 g and a volume of 13.51 cm3.

D= m VD = ?

m = 52.547 gV = 13.51 cm3

Therefore, the density of the material is 3.89 g/cm3.

= 52.547 g 13.51 cm3

= 3.89 g/cm3

The density of silver is 10.49 g/cm3. If a sample of pure silver has a

volume of 12.993 cm3, what would be the mass?

m = ?D = 10.49 g/cm3

V = 12.993 cm3

m= D x V = 10.49 g/cm3 x 12.993 cm3

= 136.2966 g= 136.30 g

The mass of the sample would be 136.30 g

Pure gold has a density of 19.32 g/cm3. How large would a piece of

gold be if it has a mass of 318.93g?V = ?D = 19.32 g/cm3

m = 318.93 g

V = m D

= 318.93 g 19.32 g/cm3

= 16.508 cm3

= 16.51cm3Therefore, the volume of gold would be 16.51 cm3.

Practice Problems1) What is the density of a substance with a volume of 30 cm3 and a mass of 14 g?

Answer: 0.47 g/cm3

2) What is the mass of a substance with a density of 1.12 g/cm3 and a volume of 15 mL?

Answer: 17 g

3) What is the volume of a substance with a density of 0.78 g/cm3 and a mass of 15 g?

Answer: 19 cm3

How can you measure Volume?3 ways to measure Volume:

1) Use a ruler to measure (for regular shaped solids) and the equation V = l x w x h2) Using a graduated cylinder (for liquids)3) Displacement using a graduated cylinder (for irregular solids) using chart below:

Trial Initial Volume

(mL)

Final Volume(mL)

Volume of Unknown

(mL)

Unknown irregular shaped object

1

2

Average volume

How can you measure Mass?

For solids:- use an electronic balance

For liquidsFor liquids:- use an electronic balance to mass

a graduated cylinder with and without the liquid, then subtract

Lab Activity• Determine the identity of

Unknown Materials (2 liquids and 2 solids)

- see lab sheet

Good Luck!