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!
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