DENSITY

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# DENSITY - PowerPoint PPT Presentation

DENSITY. How dense is dense?. What’s the matter?. Matter exists in 3 main forms: solid liquid and gas. Density is the concentration of matter (atoms) in a substance. Silicon atoms. Density is a ratio. The density of an object is the ratio of its mass (g) to its volume (cm 3 or ml). A. B.

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Presentation Transcript

### DENSITY

How dense is dense?

What’s the matter?
• Matter exists in 3 main forms: solid liquid and gas.
• Density is the concentration of matter (atoms) in a substance.

Silicon atoms

Density is a ratio
• The density of an object is the ratio of its mass (g) to its volume (cm3 or ml).

A

B

C

Density calculations convert to metric

2.54cm = 1 inch

Length = ?

Width = ?

Height = ?

Volume = ?

454g = 1lb

Mass = 30.98lb

Mass = ?

7 X 3.625 X 1.75in.

Density equation
• Density = Mass

Volume

• D = M

V

M

V

D

Density calculations

2.54cm = 1 inch

Length = 17.78cm

Width = 9.21cm

Height = 4.45cm

Volume = ?

454g = 1lb

Mass = 30.98lb

Mass = 14,064.9g

7 X 3.625 X 1.75in.

Work

Volume

17.78cm X 9.21cm X 4.45cm = 728.7 cm3

Volume = 728.7 cm3

Mass

30.98lb X 454g = 14,064.9g

1lb

Mass = 14,064.9g

More work

D = M

V

D = 14,064.9g

728.7 cm3

D = ?

More work

D = M

V

D = 14,063.9 g

728.7 cm3

D = 19.3 g/cm3

Effect of phase of matter on density
• Most substances increase in density as they change from gas to liquid to solid.
• Quite simply, the atoms are closest together in the solid phase.

gas E liquid E solid

decreasing density

increasing density

Water is an exception

ice liquid water water vapor

• Water is densest as a liquid at 3.98oC. That’s why ice floats.
Factors that affect density
• Temperature
• Heat - pushes molecules apart
• Cold - pushes molecules together
• Pressure
• Low - allows molecules to spread apart
• High - pushes molecules together
• It’s the volume that changes and density is dependent on the ratio d=m v
Float?
• If the density of an object is less than the liquid it will float.
• The lower the density of an object the higher it will float in the liquid.
Sink?
• If the density of an object is greater than that of the liquid, it will sink.
???
• If an object and a liquid have the same density, the object can remain stationary anywhere in the liquid.
Layering
• Liquids of different densities will form layers.