Year 9 Science: Chemical Reactions

Chemical Reactions Notes

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Thanks to Duncan Patti for producing the slideshow above, which is a good summary of what you should know about chemical reactions from Year 7 and 8 science and an introduction to Year 9 Chemistry. You need to know the difference between a physical change and a chemical reaction (what evidence is there for a chemical reaction?). You also need to know the four ways in which you can increase the rate of a reaction. It is also very helpful if you can remember the chemical formula for the first twenty elements, as well as some other common ones (iron, copper, silver and lead).

Year 7 Science: Separating Mixtures

Learning Intention: Students will understand that the different properties of substances allow them to be separated in different ways – particle size, density, magnetism etc.

Success Criteria: Students will be able to identify 10 different methods of separation and give an example of each. They will be able to draw a flow chart to separate a mixture of sand, salt, rice and iron filings.

This term in Year 7 Science you will be starting a unit of work on Separating mixtures. You will be learning about the following processes and how they are used when separating mixtures:

  • Centrifuging
  • Crystallization
  • Chromotography
  • Distillation
  • Evaporation
  • Filtering
  • Froth Flotation
  • Gravity Separation
  • Magnetic Separation
  • Seiving

Can you think of some examples of how these methods are used in the home and in the workplace? At the end of this unit of work you will be asked to separate a mixture of salt, sand, rice and iron filings.  Download a worksheet to check your understanding of the definitions for each of these processes here:  Separating Mixtures worksheet
You may like to try these quizzes:

Check out the Year 7 wiki for more about Separating Mixtures.

It’s a Material World!

So far this term we have done lots of experiments to demonstrate the properties of different materials, such as:

  •  “Making Rayon – a regenerated fibre”;
  • “Making a Colloid – sulfur and methylated spirits in water”
  • “Making a Gel” and
  • “Cold cream – an emulsion”.

Well done Sarah and Emma for making their own homemade cosmetics – an exfoliating gel with poppy seeds and a shampoo from an emulsion of honey and egg yolk. The image above is from Quizlet, where you can create your own flashcards, scatter games and other activities to assist you to remember the improtant terms and definitions for this unit of work.

Materials scientists are constantly working on innovations to improve the manufacture and use of fabrics, structural materials and packaging. This article, from Web Urbanist, describe “8 Substances that will shape the future“.

While I am on Year 7 camp at Roses Gap (19th to 21st March) those Year 9 students not on the Advance camp should be studying for their science test. This test will be on Friday 23rd March and include all the work we have done this term. You should read your text book chapter and write some study notes as well as review your workbook with the practical experiments we have completed.

Welcome Back – Year 9 Science 2012!

Welcome back to school for another fabulous year of science and learning! Please bookmark this site for future reference as this will be the starting point for all our science studies during the year. Our first unit of work will build on your knowledge of matter, atoms and molecules, elements and compounds and chemical reactions.

Learning Intention:

(1) Students will understand that all matter is made of atoms which are composed of protons, neutrons and electrons; natural radioactivity arises from the decay of nuclei in atoms.

(2) They will know that chemical reactions involve rearranging atoms to form new substances; during a chemical reaction, mass is not created or destroyed.

(3) Students will understand chemical reactions, including combustion and the reactions of acids, are important in both non-living and living systems and involve energy transfer.

Science Test on Tuesday 14th June

 

Next Tuesday, year 8 students will have the opportunity to demonstrate what you have learnt about chemical reactions this term. You will be asked to complete a test with about 18 multiple choice questions and some short answer questions. What are some good ways to do revision for a test?

  • Find a quiet and comfortable place to study.
  • Write out a list of key words and put them each into a meaningful sentence.
  • use “Chemical Reactions flashcardsdb” to study important terms.
  • Draw a mind map showing the connections between different concepts.
  • Read through Chapter 3 of your text and answer the “Remember” and “Think” questions.
  • Look through your notes taken in class and highlight important definitions and concepts.
  • Read some more study tips at Youth Central.
  • Try this MyStudiyo quiz about Chemical Reactions

What’s your pH? – Acids and Bases

red_cabbage

Creative Commons Image from Britt Gow

Learning Intention: To develop an understanding of acids and bases and the chemical reactions they are part of.

Success Criteria: You will be able to describe the differences between acids and bases and give several household examples of how they are used. You will perform some simple chemical reactions and identify that the  colour changes indicate the pH of the mixture.

Today we will be doing an experiment with acids and bases – making a pH indicator using red cabbage and testing various household substances. PH is a measure of the acidity (ph is less than 7) or alkalinity (ph is greater than 7) of a substance.

Another experiment we will do this week demonstrates how antacids work in your stomach. We will add dilute hydrochloric acid to a conical flask, which simulates the gastric juices in your digestive system. We will then add universal indicator to show the level of acidity. We will then add an antacid (alka-seltza tablet) and show how the pH increases, which demonstrates that the solution has become less acidic. When an acid and a base are mixed together the chemical reaction that takes place is called a neutralisation. The acid and base react to form a salt and water.

When metals are placed in acid they can corrode. An acid and a metal react together to produce hydrogen gas and a salt. You can test for hydrogen gas using the ‘pop’ test – light a match at the mouth of the test tube and you will hear a ‘pop’. Acid rain is problem in the northern hemisphere, caused by air pollution. We will learn more about acid rain in class.

Chemical Reactions

chemical reaction collage

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”.

Chromotography with Smarties and Autumn leaves

smarties#2

Chromotography  is a collective term for a set of laboratory techniques used to separate mixtures. It includes paper chromotography, thin-layer chromotography and gas chromotography. Paper chromotography is used for separating mixtures such as inks and dyes. In our practical experiment, we will use the natural food  dyes used to colour “Smarties”, although the artificial colouring used for “M and M’s” work well too. This is also a great time of year to investigate the pigments in autumn leaves – as chlorophyll breaks down to produce xanthophyll, carotene and anthocyanin. Another experimental method for leaf chromotography here.

Why do some trees have leaves that change colour in the autumn? How is chromotography used by forensic scientists and in industry? Please do some research and post your answers in the comments section below.

Year 8 Chemical Reactions

Rusty tractor engine

This a rusty tractor engine, captured at Jurien Bay, WA.

Over the next few weeks we will be doing many different experiments, including turning grass into paper. After you have finished this unit of work, you should be able to answer the following questions:

  1. What are the two main differences between physical change and chemical reactions?
  2. What are four signs that new products are formed during a chemical reaction?
  3. Name four ways you can increase the rate of a reaction.

Freezing, melting, evaporation and condensation are all physical changes of state in which molecules of a substance gain or lose kinetic energy. Many common changes that occur around us are actually chemical reactions – when iron rusts, apples go brown, silver tarnishes or copper develops a green tinge, oxidation is occurring. Combustion (burning) is also a form of oxidation. In a chemical reaction new products are formed and this may result in a colour change, a precipitate being formed, the release of gases or energy in the form of light or sound. The following resources may help you to learn about chemical reactions:

Check out our Voicethread about Chemical reactions:

 

What would you like to learn about in Science next? Please go to the Wallwisher and leave a post-it note letting me know what you are interested in doing in Year 8 Science.

Year 7 Science: Separating Mixtures

 

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Over the next fortnight I will be on long service leave and Mr Foreman will be taking my classes. In Year 7 Science you will be starting a unit of work on Separating mixtures. You will be learning about the following processes and how they are used when separating mixtures:

  • Centrifuging
  • Crystallization
  • Chromotography
  • Distillation
  • Evaporation
  • Filtering
  • Froth Flotation
  • Gravity Separation
  • Magnetic Separation
  • Seiving

Can you think of some examples of how these methods are used in the home and in the workplace?
Download a worksheet to check your underdstanding of the definitions for each of these processes here:  Separating Mixtures worksheet
At the end of this unit of work you may like to try these quizzes:

Check out the Year 7 wiki for more about Separating Mixtures.