Students will...
- Understand the difference between a solution and a pure substance
- Be able to define different types of substances as mixtures, solutions or pure substances
- Be able to give examples of gaseous, solid and liquid solutions
- Define solution/solvent and understand their relationship
Expected Background Knowledge
Students should have prior knowledge from grade 9 science regarding matter, physical/chemical changes, elements and other factors of physical science relating to chemistry.
Students should have prior knowledge from grade 9 science regarding matter, physical/chemical changes, elements and other factors of physical science relating to chemistry.
(BC Ministry of Education, 2006)
- A substance is pure based on visual observation alone
- Solutions can only be liquid
- Compounds are mixtures
- A mixture and a solution are the same thing
Difficulties
A fun extension for this subject that is also cross-curricular would be a baking class! Baking is a very important form of chemistry as it results in tasty treats. This may appeal to many students that enjoy the culinary arts and help link the importance of chemistry to their interests.
Ideas would include creating heterogenous and homogeneous mixtures in the form of batters and final products. Students could also be asked to translate their recipe into scientific terms using the appropriate vocabulary learned in class.
- Describing the differences between pure substances and solutions can be hard to understand for visual learners. Using videos or in-person examples can help explain more clearly.
- Mixtures and solutions may be assumed as the same property. Explaining the difference between heterogenous and homogenous mixtures will help make the varying characteristics more clear.
- Overload of working memory space (remembering and processing) (Sirhan, 2007)
- Language (unfamiliar vocabulary) (Sirhan, 2007)
- Motivation (Sirhan, 2007)
- Students do not apply their knowledge to the real world (Sirhan, 2007)
- Misconceptions in chemistry are common (Sirhan, 2007)
- Requires Macroscopic & Microscopic thought process (Sirhan, 2007)
- Anticipation reaction guide (Loughran, 2010)
- Students will first be refreshed about matter, the different types and their interactions (pure substances & mixtures, homogeneous and heterogeneous)
- Place three beakers in front of your students, one is filled with water, the other is filled with salt water and the other, sugar water. Explain that despite looking exactly the same visually, the three beakers are not the same. One is salty, another sweet and the last is water.
- Mix water and different solids (salt, sugar, sand, rocks...etc) as visual aids, ask the students to describe what they are observing.
- Introduce solvents & solutes and use an online simulation activity involving solutions so that students can make observations on what happens when solvents & solutes interact with each other. Have students write a reflection on their observations and additional questions they may have. (PhET, 2011)
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(resource: phet.com)
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- Bring examples of solutions in different formats to class. To relate with the real world it could be maple syrup (liquid solution), a balloon full of air (gas solution) or a brass instrument (solid solution).
- Show a short video to the class that displays the differences between pure substances and mixtures microscopically to help them understand what is happening.
- Students could be asked to create a mind-map or fact-file for the characteristics of pure substances and solutions in relation to matter. (Loughran, 2010)
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| (http://www.culinate.com/) |
Ideas would include creating heterogenous and homogeneous mixtures in the form of batters and final products. Students could also be asked to translate their recipe into scientific terms using the appropriate vocabulary learned in class.
