EXPERIMENTAL INVESTIGATION 26.2 How can we compare the density of liquids?
Equipment Mass balance Graduated cylinder
Suggested substances to test Honey Water
Vegetable oil Washing-up liquid
Method 1. Use the mass balance to measure the mass of a graduated cylinder. 2. Carefully place 50 ml (50 cm3
) of liquid into the cylinder.
3. Record the new mass of the cylinder and liquid and subtract the readings to calculate the mass of the liquid added.
4. Calculate the density of each liquid by dividing its mass by its volume. Record your results. 5. Follow steps 2–4 with other liquids. Compare the densities of the liquids.
Graduated cylinder
Milk
50 ml (50 cm3
) Water
g
g
Mass balance : Fig. 26.4 To compare the density of liquids j Go to page 76 of your Experimental Investigations Log to write up this investigation. Flotation
Flotation describes how well an object or substance floats when it is placed in another substance, such as a liquid or gas.
• If an object has a lower density than the substance it is in, it will float.
• If an object has a greater density than the substance it is in, it will sink.
For example, helium has a lower density than air, which is why helium-filled balloons float.
) Fig. 26.5 Helium-filled balloons float in air 256 Elements of Science