Core practical: densities of solids and liquids

1. Zero the balance, then measure the mass of the object.
2. Regular solid (such as a cuboid): measure its length, width and height with a ruler (or vernier calipers for small objects). Volume = length × width × height.
3. Irregular solid (such as a stone): fill a displacement (eureka) can with water until it runs out of the spout, and wait for the dripping to stop. Put an empty measuring cylinder under the spout. Lower the object in gently on a thread. The volume of water that flows out equals the volume of the object.
4. Another way: put water in a measuring cylinder, read the level, add the object and read the level again. The rise in level is the object's volume.
5. Calculate density = mass ÷ volume.

1. Put an empty measuring cylinder on the balance and zero it (or record the mass of the empty cylinder).
2. Pour in some of the liquid, for example 50 cm³, and read the volume.
3. Record the mass. This is the mass of the liquid only (if you recorded the empty mass, subtract it).
4. Calculate density = mass ÷ volume. Using a larger volume of liquid makes the percentage uncertainty in your readings smaller.
Read the volume at eye level from the bottom of the meniscus to avoid parallax error.
Safety: wipe up spills, keep water away from the balance and other electrical equipment, and lower heavy objects gently so the glassware does not crack.

ρ = m ÷ V. With mass in g and volume in cm³, density is in g/cm³. With kg and m³, it is in kg/m³.
1 g/cm³ = 1000 kg/m³, and 1 cm³ = 1 ml.
Water has a density of about 1 g/cm³ (1000 kg/m³). Objects less dense than water float in it.
Repeat each measurement and calculate a mean. Errors to watch for: water splashing out of the displacement can, air bubbles stuck to the object, and liquid left behind when pouring.