Density

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Physical Properties

The physical properties of a substance describe things such as:

• ​Its appearance

• The temperatures at which it melts, freezes and boils

• Its hardness (how easily it is to scratch the material).

​Density is one of the physical properties of a substance.

What is density?

Density is a measure of how much matter is packed into a space.

Density depends on how heavy a substance is, but it is not the same as its weight or mass. For example, 1 kilogram of lead always weighs exactly the same as 1 kilogram of polystyrene, which weighs as much as 1 kilogram of feathers.

​Same mass but take up different amount of space.

How to talk about density

Density is the mass of something compared to its volume. Therefore, we talk about density in terms of grams per cubic centimetre (g/cm³).

Multiple Choice

What is density?

• The comparison of how much matter in an object to how much space it takes up

• A ratio of mass to volume

• How tightly packed the molecules are in an object

• All of the above

Multiple Choice

Oil is __________ dense than water.

• More

• Less

• I'm not sure

Multiple Choice

Liquid water is more dense than ice because:

• The volume of the liquid increases when it freezes

• When ice melts there is an increase in the amount of molecules

• Liquid water molecules have more mass than ice molecules

• A chemical change occurs as ice melts that causes the mass of water to increase

Multiple Choice

Two liquids, A and B, have densities 0.75 g/cm³ and 1.14 g/cm³ respectively.

When both liquids are poured into a container, which liquid floats on top?

• Neither, they mix evenly

• Both; they keep trading places like a lava lamp

• B

• A

Multiple Choice

A substance is cut into several pieces. As compared to the density of the original sample, the density of each piece will be:

• Greater

• Less

• The same

• None of the above