Mystery powders 01

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Edit   Delete - Last Modified By: rdu at 23/07/2014 12:32:16 PM

When sugar or salt (solute) is stirred into water (solvent), we expect to see the sugar or salt "disappear".  When substances dissolve, they are broken into very tiny particles and are spread throughout the water, which is called a solution.  Although they cannot be seen, the sugar or salt particles are still there.  Sugar and salt are soluble in water.  A substance or solute that does not dissolve in a solute is said to be insoluble. 

Solubility in water is one part of the attached experiment to distinguish between a variety of white powders.  The experiment also uses the description of physical properties, addition of heat, testing with iodine and testing with vinegar to help determine which powder is which.  

Edit   Delete - Last Modified By: rdu at 23/07/2014 12:23:01 PM

We are surrounded by objects that are solids, liquids and gases.  What you see are physical properties.  Physical properties of a substance may include:

1. whether it's a solid, liquid or gas at room temperature

2. the temperature at which the substance freezes (freezing point) or boils (boiling point)

3. its appearance, including colour, texture, shape of crystals, shiny, dull

4. its density - how heavy it is compared to other substances of the same size

5. how hard or brittle the substance is

6. whether the substance dissolves in different liquids

7. its ability to let heat or electricity pass through it (thermal and electrical conductivity)

Can you describe some of the physical properties of objects around you? 

 

Chemical properties describes how a substance reacts with other substances.  A new substance is formed in the process, often with very different properties.  

Chemical properties may include:

1.  burning or exploding in oxygen (known as combustion)

2. rusts or corrodes (known as corrosion)

3. is an acid (like vinegar) or a base (like bicarb soda)

4. reacts quickly or slowing with other chemicals (known as the rate of reaction) 

Can you describe some of chemical properties of objects around you?

Edit   Delete - Last Modified By: mbai at 16/05/2017 11:38:23 AM
Edit   Delete - Last Modified By: stu at 8/07/2015 10:48:41 PM

Watch the following videos and then answer the questions below:

1. What are the three states of matter?

2. What are examples of each the different states?

3. What are the physical properties of each state?

4. What does soluable, insoluable and solvent mean and provide examples of each?

Edit   Delete - Last Modified By: stu at 8/07/2015 10:50:02 PM
Edit   Delete - Last Modified By: rdu at 23/07/2014 12:27:56 PM

If you are given 5 different white powders, how can you accurately determine what each powder is?  Read through the following link which will outline how you will:

- describe each powder's physical properties

- test each powder's solubility in water

- test each powder with heat

- test each powder with iodine

- test each powder with vinegar

After you have completed these tests, if you were given a unknown mixture of some of these white powders, could you work out which powders were in the mix?