What is a chemical change
Changes are very random or an uncertain phenomenon, it can be better or worse depending on your view. Every day we see different objects changing around us like melting of ice, cooking of food etc. In some cases, you get back the original substance and in some, you won’t get it back. Some changes are slow while some are fast, some are natural and some are man-made. You will find that many changes are taking place around us for e.g. growing of plants in your balcony, sometimes there is a change in colour and sometimes you will find drying of leaves.
Chemical Change Definition
A chemical change can be defined as a chemical reaction in which one or more substances undergo changes to form new substances or a new structure.
Types of chemical change
Changes are mostly of two types
- Reversible change
- Irreversible change
Reversible change is that change that can be reversed by one or more methods. In this kind of change, there is a change in physical properties, shape, and size of the material. Mostly a new substance is not formed in a reversible change. For example folding of paper, elongation of spring etc.
The change which is almost permanent and cannot be undone by any physical or chemical means is called an irreversible change. Some new substances are formed in the case of an irreversible change.
There are many advantages of reversible and irreversible changes. For example, a piece of iron is cast into different shapes by a blacksmith. It is beaten into the desired shape after it is heated. On heating, the metals expand while it contracts on cooling. By this, you can understand why there are small gaps left between the rails in railway lines. This is because the metal tracks expand in summers due to high temperature. Thus, these gaps compensate for the increase in area due to expansion.
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