Density

Density is the quantity related to how closely packed the particles in a material are, as well as how much the particles weigh.

Measuring density

As the equation above shows, all we need to know in order to calculate the density of a substance is the mass and volume. Let’s take a look at some examples.

Determining the density of a liquid

Put a measuring cylinder on a weighing scale and reset it to 0
Pour the liquid into the measuring cylinder and measure the volume
The weight of the liquid is found by reading off the weighing scale
Calculate density

Calculate density of regular solid

Measure the dimensions of the solid (height/weight/width)
Measure the weight of the solid on a weighing scale
Volume of solid = height X weight X width
Calculate density

This method is only possible if the solid has a regular square or rectangular shape. If the shape is irregular then the displacement method should be used (as below)

Calculate density of irregular solid

Measure the weight of the solid via a weighing scale
Add water into a measuring cylinder and measure it’s initial volume
Submerge the irregular solid into the measuring cylinder
The solid will displace the water causing it to rise
Measure the new volume reading
The volume of the solid = new volume reading – initial volume reading
Calculate density

Predicting flotation

The density of an object determines whether it will float or sink in another substance.

An object will float if it is less dense than the liquid it is placed in
An object will sink if it is more dense than the liquid it is placed in