Density

Why did the liquids settle in a specific order?

Why can some heavier objects float while some lighter objects sink?

Density…

Is a property of all matter: solids, liquids and gases.

Is found by dividing an object’s mass by its volume.

Units for mass: _____ Units for volume: _____

Density…

Measures how tightly matter is packed within an object

Symbol = rho (ρ)

Calculating Density

Mass

---------- = Density

Volume

Examples

A block with a volume of 15 cubic centimeters has a mass of 52.5 grams. What is its density?

Mass

------------

Volume

Mass = 52.5 g

Volume = 15 cm3

Divide!

Density = 3.5 g/cm3

Examples

A die (1.5 cm on each side) has a mass of 3.6 g. What is its density? Will it float?

Mass

------------

Volume

Mass = 3.6 g

Volume = 3.4 cm3

Divide!

Density = 1.1 g/cm3

Examples

You have a piece of metal with a volume of 245 cm3 and a mass of 612 g. Is it aluminum (which has a density of 2.70 g/cm3)?

A 14.0 cm3 ice cube has a mass of 12.83 g. What is the density? Compare this to the density of water. What does this tell you about the ice?

Examples

A jar has a volume of 953 cm3. If a scientist measures the mass of the gas in the jar at 0.158 g, what gas is probably in the jar?

Oxygen: 0.00133 g/cm3

Nitrogen: 0.00117 g/cm3

Helium: 0.00016 g/cm3

Hydrogen: 0.00008 g/cm3