Irreversible changes are permanent changes that cannot be undone. Cooking, baking, frying, burning, mixing, rusting, heating are examples of irreversible changes.
Following are some of the irreversible changes examples.
Example – You cannot change a cake back into its ingredients.
Example – When you heat a raw egg to make a cooked egg, the fried egg cannot be changed back to a raw egg again.
Example (1) – When vinegar and bicarbonate of soda are mixed, the mixture changes and lots of bubbles of carbon dioxide are made. These bubbles, and the liquid mixture left behind, cannot be turned back into vinegar and bicarbonate of soda again.
Example (3) – If water is added to plaster of Paris powder and the mixture is then allowed to stand, it sets hard. A new substance has been formed.
Some Rusted Things
Example – When you burn a piece of paper, first the paper changes colour then it bursts into flame and gives off a lot of heat and smoke. Soon it ends up as black ash. You cannot change the ash and smoke back to paper.
Milk is turned into cheese or yoghurt by different kinds of bacteria. We cannot turn cheese or yoghurt back into milk.