Density

Density

• Density is the relationship between an object’s mass and its volume.

• Mass is the amount of ‘stuff’ in an object.

• Volume is the amount of space that object occupies.

Density = Mass Volume

• Weight is the heaviness or mass of an object.

• Displacement is the change in water level caused by immersion of an object.

Temp and Pressure

• The factors that have the greatest effect on density are Pressure and

temperature.

• As pressure increases, so does density. It’s a direct relationship.

• As temp increases, density decreases. It’s an inverse relationship.

• Increasing pressure generally causes an increase in density by decreasing the volume.

• Increasing temperature causes a decrease in density because heating objects generally causes them to expand, increasing the volume.

• Size and shape have NO EFFECT on density!

• The same object will always have the same density – as long as the pressure and temperature are the same.

Matter

• Matter comes in three states:

1. Solid ~ Most dense

2. Liquid ~ Moderate density

3. Gas ~ Low density

• Generally speaking, the highest density is usually in the solid state, except for water. Water is most dense in its liquid state.

Liquid Density

• Liquids have unique densities depending on what they are. For example:

• Water = 1 g/cm3

• Glycerine = ~ 1.25 g/cm3 (Greater than water)

• Vegetable oil = ~ 0.91g/cm3

(less than water)

Oil

Water

Glycerine

So. . .

• Pressure and temperature are the two factors that have the greatest affect on density.

• Mass and volume are the variables we measure to calculate density.

• Size and shape have no affect on density. • Objects that are the same substance always

have the same density, regardless of size and shape.

Therefore . . . • Density is a ratio between mass and

volume. Mass is the amount of ‘stuff’ in an object and volume is how much space that object occupies.

• As pressure increases, so does density. (A direct relationship).

• Inversely, as temperature increases, density decreases because of increasing volume. (An inverse or indirect relationship).