Paper made out of banana tree
You use stacks of paper every day but do you know how it’s made? Paper has been made since 105 AD in China, but other materials such as papyrus (in Egypt), parchment and vellum (various grades of mammal skin) were used in other parts of the world prior to this. Find out more about the history of paper at Wikipedia.
In Sri Lanka, a fair trade company is making paper from elephant pooh! In that country, humans are encroaching on elephant habitat, cutting down trees for fire wood and shooting and killing elephants that come looking for food. This company, “Mr. Ellie Pooh” aims to create employment and encourage villagers to see the elephants as an asset rather than a threat.
Compared to using virgin wood, paper made with 100% recycled content uses 44% less energy, produces 38% less greenhouse gas emissions, 41% less particulate emissions, 50% less wastewater, 49% less solid waste and — of course — 100% less wood.
This week we are making paper from grass in six steps:
- Cut the grass and grind it with the mortar and pestle
- Add caustic soda to release the cell contents
- Wash and rinse to remove chemicals and cell contents
- Add bleach and bring to the boil
- Wash and rinse to remove the bleach
- Form the paper
Which of these steps are physical changes and which are chemical changes?
Collage created using Photovisi
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”.