Free Exam Academy

Density

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