Rotten apple.

To start with this experiment, after explaining what we are going to do we put the different stages in the correct order. We are going to cut an apple in four segments and we are going to cover three of them with salt, baking soda, and water, we will leave one of them naturally, we will place them in a cool, dark place, we will wate for some days and see what happens.

Then, as we do in every experiment we make we will make our predictions, and we will prepare our record sheet.

After some days we see the results. We can see that the segment with table salt is dry but not rotten at all, it is perfectly edible and we also see that the one with baking soda has changed  colour but when we cut it, it is not rotten. Unfortunately the  segment into water has rot and  the segment with no substance at all is ruined. It even has mould!
This teaches us that there are ways of preserving aliments for longer, like covering them with salt, this is what we do with ham and some fish.
We observe here a chemical change. We don´t have the same matter any longer, the rotten material is not apple, it is something different and it is impossible to turn that into apple again.
We will see many other examples of physical and chemical changes next day.

table salt

baking soda

Water.

nothing at all.