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