Science of Healthy Skin: Investigating what happens when oil is added to water

Full details of the activity can be found in the CIEC resource 'Science of Healthy Skin’ which can be downloaded from: http://www.ciec.org.uk/resources/science-of-healthy-skin.html

Based upon the extraction of lanolin from wool grease, the activities in this resource include testing immiscible liquids using oil and water and investigating the effects of adding detergent to produce emulsions which in turn reduce the efficiency of the separation of oil from water.

The Activity: Fleece to Grease

Resources 

• 300 ml water
• 300 ml sunflower oil
• 50 ml clear water - sample A
• 50ml clear glycerine - sample B
• 50 ml clear detergent - sample C
• 50 ml white vinegar - sample D
• 4 clear plastic mini pop bottles or lidded containers around 30ml per group of 4 children
• Pipette x 1 for each child
• Teaspoon or similar for stirring
• 100 ml measuring cylinder 

Objectives

• To describe changes that occur when materials are mixed
• To make systematic observations and measurements
• To know that that some liquids do not mix, can be separated easily and are termed ‘immiscible’
• To observe that detergent can cause immiscible liquids to mix, producing an emulsion

What happens when oil is added to water?

Each child in the team of 4 to pour 10ml of water and 10ml of oil into one of the containers.

Ask them to wait for 1 minute to see what happens to the oil and water.

Tip the containers upside down four times and ask the children .....

• Did the oil and water mix?
• Did shaking make the liquids mix?
• Why do you think this happened?

The oil and mixture quickly separate when they are on their own.  But will adding any of the other ingredients make a difference?

Investigate whether adding sample A, B, C or D affects the separation of water and oil.

Using the pipette, add 10 drops of sample A to one of the bottles, 10 drops of sample, B to another bottle and 10 drops of samples C and D to the other two bottles.

Ask children to observe how long it takes for the oil and water to separate after 4 shakes.

Ask them to consider how they will record their observations.

Health and Safety

Remind the children not to drink their samples.

Links to the National Curriculum for Science:

Working Scientifically

Learning Objectives

• planning different types of scientific enquiries to answer questions, including recognising and controlling variables where necessary
• Taking measurements, using a range of scientific equipment, with increasing accuracy and precision, taking repeat readings when appropriate
• Use observations, measurements or other data to draw conclusions

Subject Knowledge

Learning Objectives

• Know that changes occur when materials are mixed and some of these are reversible