Discover and compare the viscosity of different liquids, from oil to water.
The viscosity of a liquid is another term for the thickness of a liquid. Thick treacle-like liquids are viscous; runny liquids like water are less viscous.
This experiment should take 20 minutes.
- Eye protection, if desired
- Sealed tubes of different liquids (thermometer packing tubes are ideal)
- Cooking oil
- Washing up liquid
- Shampoo or bubble bath
Health, safety and technical notes
- Read our standard health and safety guidance.
- Wear eye protection if desired.
- Ethanol is highly flammable, see CLEAPSS Hazcard HC040a.
- Take one of the tubes provided.
- Ensure the bubble is at the top and the tube is held vertical.
- Quickly invert the tube and measure the time it takes for the bubble to reach the top.
- Repeat this measurement for all the samples
- Complete a table, as shown below.
|Liquid||Time taken /s|
|Washing up liquid|
Remind students to time each liquid using a consistent method – eg measure the time from inversion until the ‘bubble first hits the top’.
- Which liquid is the most viscous?
- Which liquid is the least viscous?
- Design a different experiment for comparing the viscosity of liquids.
This practical is part of our Classic chemistry experiments collection.