Separating+Mixtures

= Separating mixtures =

1. Mixtures, suspensions, sediments 2. Colloids and centrifuge 3. Filtration and decanting 4. Water treatment story 5. Evap, Crystallization, Distillation (gum leaves) 6. Separation of coca cola (using filtration, distillation, centrifuge, adsorption 7. Adsorption and “separating solids” (gravity, electrostatic, froth, magnetic)  8. Chromatography  9. Revision and mystery experiments  10. Test

Start a new Keynote, summarising the information on this page in your own words.

Mixtures
All things can be classified as either being a pure substance OR a mixture.

// Pure Substances // contain particles which are all exactly the same. They will always have the same properties no matter where you find them.

// Mixtures // are made up of several different substances // mixed // together. A good example of a mixture is a cup of coffee. It contains coffee, water, sugar and milk. Mixtures can have different properties depending on how much of each component (subsgtances making up the mixture) is present.

Examples of mixtures.... Can fill in this table.



Solutions
Solutions are the main type of mixtures you will come accros. Mixtures which are solutions will look like they are only one thing even though there might be many other things present. For example, lets have a look at a glass of coke. We know it contains sugar, carbon dioxide, colouring and water, but because these substances are all mixed together (the sugar, carbon dioxide and colouring are dissolved in the water) coke looks like it is just one thing instead of a mixture of 4 different things. We can say that **in a solution the properties are the same everywhere**.

Solutions can be solids, liquids and gasses. Can you think of an example of each? // This is actually a bit tricky... you may need the help of others in the class... and you might have to do a bit of research //

// Solid solution = ? // // Liquid solution = ? // // Gas solution = ? //

Suspensions
Suspensions are mixtures which contain a solid (maybe tiny mud particles) which is evenly distributed in a liquid. A good example of this is water from the Murray River. It contains tiny particles of clay which are distributed evenly throughout the entire liquid. This is why it looks muddy. If this was left to stand for a long time it would eventually begin to separate and the larger clay and mud particles would sink to the bottom of the solution. When they settle to the bottom, this is called a **sediment**.

Colloids
Colloids are in between solutions and suspensions. They consist of a liquid with tiny particles suspended in it, however if left to stand, these particles will never settle out. If we took a sample of Murray River water and left it to stand, some of the particles would settle out forming a sediment. The ones which didn't can be called a colloid.

There are many different types of colloids and they can be made up of solids, liquids and gasses. A liquid in liquid colloid is called an emulsion. A great example of an emulsion is Milk, which contains tiny fat particles spread throughout the water. If you want to prove this to yourself, heat some milk on the stove and add some vinegar (this will make the fat particles clump together).

Yes centrifuges can be dangerous. Always be careful. Maybe this guy should have worn a helmut.
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 * 1) Identify what forces are operating in the centrifuge.
 * 2) How are they useful for separating mixtures?
 * 3) What kind of mixtures can be separated using a centrifuge?

How to separating mixtures
Mixtures can be separated by using the different properties of the substances that are mixed together in them.

Blood contains a watery serum as well as red and white blood cells. The red blood cells are heaviest. Laboratories spin the blood in a centrifuge so that the heaviest components move to the bottom. Centrifuges mimic gravity. It is easier to jump if you are small and light.

You can also separate mixtures in much easier ways.
 * 1) You can pour off the fluids. This is called decanting. You do this when you poor a cup of tea from a tea pot leaving the tea leaves behind.
 * 2) You can filter. In a lab we use filter paper. At home you use a strainer.... what else can we use?
 * 3) You can evaporate. This is how people get salt from sea water... and what happens when you forget to take a saucepan off the stove.
 * 4) You can centrifuge... as described above
 * 5) You can distill... this process uses the different evaporation points of liquids in a solution. Once evaporated, the gases are cooled and condense to their liquid form. If you distill oils from gum leaves the oil will float on top and can then be decanted off as pure Eucalyptus oil.

Some methods are more expensive than others, or are not necessary in all situations. Read about what happens at a water filtration plant.

Imagine that you are a water atom travelling through the plant.. begin in a river... and end up in a glass of water. Describe what happened to you in a 100 word story.
Advanced Task (for those of you who are ahead)

**Distillation Prac**
Download the following Pages document and fill it in as you do the practical.

=**Challenge...**=

Your challenge for today's lesson is to find a method to separate a complex mixture of sugar, gas, water, flavour and colour. This mixture is commonly known as coca-cola. You may use any of the techniques we have learnt so far or you may try a new one with permission from the teacher. Before you start you need to fill in the following pages document. Please download and save this document to your science folder.

Possible ideas for your experimental method could be the use of:


 * Filtration**
 * Centrifuge**
 * Distillation**
 * Evaporation**
 * Adsorption (using activated carbon)**



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You will also have to design a multiple choice question on one aspect of the topics you have studied in this chapter. Your question and answer must be scientifically accurate, however you also need to include 3 incorrect, but plausible answers. Email these to your teacher. They will be put together to create an online multiple choice test for this topic.======