5.3 Determining Density

Describe how to determine density using direct measurements of mass and volume.

Density of a regular solid

1. Measure the mass using a balance
2. Measure the width, length and height using a ruler
3. Calculate volume (V = w x l x h)
4. Calculate density (ρ = m/V)

Density of a liquid

1. Measure mass of empty measuring cylinder using a balance
2. Measure mass of liquid and measuring cylinder
3. Subtract 1. from 2. to calculate the mass of the liquid
4. Measure volume of liquid (using measuring cylinder)
• NB: measure to the bottom of the meniscus
5. Calculate density (ρ = m/V)

Results: Oil

1. m = 15.74g
2. V = 18.00cm³
3. ρ = 15.74/18 = 0.87g/cm³

Density of an irregular solid

1. Measure mass using balance
2. Measure volume using the ‘displacement’ method
• (submerge solid in ‘Eureka can’ and measure overflow)
3. Calculate density (ρ = m/V)

Results: Stone

1. m = 146g
2. V = 42cm³
3. ρ = 146/42 = 3.5g/cm³