Measuring density

Measuring the density of different objects

There are different ways to investigate density. In this required practical activity, it is important to:

• record the mass accurately
• measure and observe the mass and the volume of the different objects
• use appropriate apparatus and methods to measure volume and mass and use that to investigate density

Aim of the experiment

To measure the density of various materials.

Method

Method 1: Stone or other irregular shaped object

1. Place the stone on the mass balance and measure its mass.
2. Fill the displacement can until the water is level with the bottom of the pipe.
3. Place a measuring cylinder under the pipe ready to collect the displaced water.
4. Carefully drop the stone into the can and wait until no more water runs into the cylinder.
5. Measure the volume of the displaced water.
6. Use the measurements to calculate the density of the stone.

Method 2: Water (or any liquid)

1. Place the measuring cylinder on the mass balance and measure its mass.
2. Pour 50 cm³ of water into the measuring cylinder and measure its new mass.
3. Subtract the mass in step 1 from the mass in step 2. This is the mass of 50 cm³ of water.
4. Use the measurements to calculate the density of the water.

Results

Some example results could be:

Analysis

Using those results, the densities can be calculated using:

Density = mass ÷ volume

Density = mass ÷ volume = 33 ÷ 4.19 = 7.9 g/cm³ (= 7,900 kg/m³ )

For a stone of mass 356 g, the volume of water displaced into the measuring cylinder is 68 cm³

Density = mass ÷ volume = 356 ÷ 68 = 5.2 g/cm³ (= 5,200 kg/m³ )

Mass of 50 cm³ of water is found to be 50 g. 

Density = mass ÷ volume = 50 ÷ 50 = 1 g/cm³ (= 1,000 kg/m³ )