3-FAM-06
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Outcomes
- Pupils should understand that in order to form vapor, the molecules of the liquid must overcome the forces of attraction between them.
- Pupils should know that the temperature of a boiling liquid remains constant, even when more heat is added.
- Pupils should understand the process of Evaporation and how it is used for cooling in a range of applications
Specification References
5.10 Understand that a substance can change state from liquid to gas by the process of evaporation or boiling.
Starter
- Using a cotton wool swab, place a drop of ethanol on the back of one hand and a drop of water on the other and discuss the feeling and the causes of it.
Main Body of Lesson
- Pupils are given a range of water samples and are asked to determine which sample is ‘contaminated’
- Find the boiling point of water samples (one distilled water/ other will salt added)
Plenary
- Pupils watch a demonstration of the forced evaporation of ether that causes water to freeze; a discussion should follow
Homework
- Plot graphs and discuss + identify contaminated water sample.
- Extension – Research -Why is the boiling point different?
Additional Information
Resources Required
- Bunsen burner kit, beakers, thermometers, samples of distilled and contaminated (salt) water
Textbook References
- Physics for you pg. 55-59
Website References
Skills Addressed
- Observations and Inferring
- Collecting data and plotting graphs
Safety/Hazards
- Pupils should be asked whether they have dry skin or cuts before applying Ethanol as it may sting. For more information see the risk assessment: The use of ethanol
- Teacher and Pupils should wear goggles as a chemical is being used.
- Ethanol should be put out of harms way before the main experiment involving bunsen burners starts.
- Pupils should not sit down whilst heating the different solutions during this experiment.
- Pupils must wear goggles and have their hair tied back and ties tucked away.
- Pupils should be told what to do if they get burnt.