Learning Intention:To distinguish between physical and chemical change and know how to influence the rate of a chemical reaction.
Success Criteria: You will be able to identify common chemical reactions and write word equations. You will be able to list the ways in which you can increase or decrease the rate of a reaction.
Year 8 students have started a unit of work learning about combustion, rusting and other oxidation reactions, acids and bases. This site, “Science Clarified”, has a good list of the different types of chemical reactions, with some examples and cool pictures. This short video, from the BBC, “Factors affecting the rate of chemical reactions” explains some of the ways that you can change the rate of a chemical reaction.
Students have performed several experiments to show the results of chemical reactions:
- Change of colour (new products formed)
- Gas production (new products formed)
- Precipitate formation (new products formed)
- Change of temperature (release or absorbtion of energy)
- Light or sound produced (indicating energy has been released)
Students have also performed an experiment to demonstrate how grass can be turned into paper, using a series of physical and chemical reactions. Each student produced a slideshow about these reactions.
- Cutting and crushing the grass (Physical)
- Digesting the grass with caustisc soda (Chemical – colour change)
- Washing the grass fibres (Physical)
- Bleaching the fibres (Chemical – colour change)
- Washing and Forming the paper (Physical)
“Five Major Chemical Reactions – video” and “Five Major Chemical Reactions – animations” are short videos from from YouTube. This blog from another Year 8 Science teacher has some great information you may be interested in: “Ms. Saenz at Mclean Middle School”. Marilyn Winter created this great Glogster about chemical reactions. Chem4Kids has a good article about “Rates of Reactions”.