2. Mix 6.5 g of iron filings with 4 g of sulfur using a spatula.
3. Can you separate the iron from the sulfur? Try to do so by placing the mixture on a piece of paper and moving a magnet below the piece of paper.
4. Mix the two elements thoroughly once again. 5. Transfer about 2 g of the mixture to a test tube. Put a mineral wool plug in the top of the tube.
6. Using a Bunsen burner, heat until the mixture starts to glow. Then turn off the Bunsen. This should be done in a fume hood or a very well- ventilated laboratory. The test tube will be extremely hot. Do not touch it.
7. Leave the contents of the test tube to cool.
Questions 1. Why was it possible to separate iron and sulfur before they were heated? 2. Did heating change the mixture? 3. Can the contents of the test tube still be called a mixture? Explain your answer.
Fig. 8 Heating a mixture of iron filings and sulfur.
Retort stand
Mineral wool plug
Iron filings and sulfur
Bunsen burner
Use a fume hood
In the above investigation the heat from the Bunsen burner gives the particles of iron and sulfur enough energy to react together. They then make a new substance called iron sulfide which has its own unique properties. A chemical change has taken place because a new substance has been made. Matter is made up of elements and compounds. When a physical change happens the elements
and compounds do not change. When a chemical reaction happens the atoms that make up the elements and compounds rearrange. This can form new compounds, or compounds can break up into the elements from which they are made. For example, the elements iron and sulfur form the compound iron sulfide. The compound water splits up into the elements hydrogen and oxygen.
Examples of physical changes and chemical changes: Physical change
1. Crushing a can
2. Sugar dissolving in water 3. Smashing a glass 4. Ice melting
5. Mixing sand and water 6. Chopping wood 7. Water evaporating
Chemical change
1. Iron and sulfur making iron sulfide 2. Iron rusting on a bicycle 3. Fireworks exploding 4. Cooking an egg
