6.6 density

Question 1

What is density?

Answer 1

Density is the mass per unit volume of a substance.

Question 2

What is the unit for density?

Answer 2

g / cm3 or kg / m3.

Question 3

How do we calculate density?

Answer 3

mass ( g ) / volume ( cm3 ) = density ( g / cm3 )

Question 4

How do we decide whether an objects floats or sinks?

Answer 4

It depends on density.

Question 5

Give an example to show that an object floats or sinks in a liquid based on density.

Answer 5

The density of ice ( 0.9 g / cm3 ) is lower than that of water ( 1 g/ cm3 ).

Question 6

A substance with a _________ density floats on top of a liquid with a ___________ density.

Answer 6

A substance with a lower density floats on top of a liquid with a higher density.

Question 7

How does temperature affect density when a substance is heated?

Answer 7

The particles move further apart, causing it to expand. Since the volume of the substance increases while the mass remains unchanged, the density of the substance decreases.

Question 8

How does temperature affect density when a substance is cooled?

Answer 8

The particles move closer together, resulting in a smaller volume of the substance, therefore the density of the substance increases.

Question 9

How do hot air balloons work?

Answer 9

When the air inside it is heated, the air particles move faster and become further apart. The air expands so its density decreases. The overall density of the balloon becomes lower than the density of the air around it so the balloon rises.