Reversible and irreversible changes

Today we started our introduction and first experiment about reversible and irreversible changes.

Background knowledge:
When you mix substances together, they may change to form a new substance. Sometimes the is reversible, while at other times it is irreversible. For example, when vinegar is mixed with baking soda, the two fizz and a new substance if formed. This change is irreversible. A chance is more likely to be irreversible if there is a reaction such as a fizz, colour change or a change in temperature.

As an introduction we watched the following video and then explored the list of reactions below to see if they were reversible or irreversible:

http://www.youtube.com/watch?v=tHM0UkhwfsQ

Dissolving sugar in water

Shaking together vinegar and oil

Mixing sand and sugar

Adding lemon juice to red cabbage juice

Adding lemon juice to baking powder

Putting chalk in vinegar

Adding vinegar to salt

Adding lemon juice to sugar

We completed all these mini investigations as a class and came up with the following conclusions:
An irreversible change is a chemical change because the substances permanently mix.
A reversible change is a physical change because you are able to separate the substances again.


To continue our scientific thinking, we also completed an investigation based on water temperature with Berocca in small groups later that afternoon.

Why don't you discuss with your child which investigations above were reversible and irreversible when they get home, or even complete the mini investigations yourselves.