Chemical change -meaning and 8 examples of chemical change
Change is something that occurs to both living and non-living thing. Change is associated with matter. This change may be temporary and easily reversing or permanent and very difficult to reverse.
These changes can be classified as physical change and chemical change. Physical change is a change that no new substance is formed. Examples are melting of ice and boiling of water. A chemical change is the opposite of physical change.
What is Chemical Change?
Chemical change is a change that occurs between two or more substances. This change leads to the formation of new substances. The new substance formed can also be known as chemical synthesis. A chemical change is irreversible. The ingredients that lead to the change are called reactants and the end results are called products.
Examples of Chemical Change
Chemical change occurs on a daily basis. Some examples are:
- Burning of wood: Woods are mainly used for cooking especially by those that own restaurants. The burning of the wood using kerosene and match stick leads to the production of new substances. The new substances or product are ash and charcoal. The kerosene and match stick are the ingredients of reaction. No process can reverse the ash and charcoal to wood again. Therefore, it is a chemical change.
- Digestion: Digestion is the process in which food taken into the body are absorbed and assimilated for the body’s use. Digestion of food is a chemical change because the food we eat cannot be the same again. In fact, the change begins in the mouth where it is chewed and grounded.
- Baking a cake: When baking a cake, several processes are taken. Ingredients like flour, eggs, milk, sugar, nut meg, baking powder among others are mixed to form a pasta. The pasta when put in an oven become a cake (product). The cake cannot be reversed to the pasta form any longer because chemical change has taken place.
- Boiling of Eggs: Raw egg has it white and yellow part as liquid form. But when boiled, the yellow and white part change to solid. This proves that chemical change has taken place.
- Ripening of fruits: Fruits undergo the ripening process. For example, unripe mango is always hard, bitter and unpalatable. When ripening takes place, the mango becomes soft, sweeter and palatable. The ripe mango cannot become unripe again because change has taken place.
- Rottening: Rottening is the process in which something decays and cannot be used again. The process which a fruit or vegetable gets rotten is known as chemical change.
- Burning of paper: When a paper is burnt, a new substance is formed.
- Cooking: Cooking itself is an example of chemical change. For example, cooking noodles will require ingredients like onion, vegetable, oil, etc. All these ingredients aid the cooking, after cooking a new substance is formed. None of the ingredients remain the same.
Differences between chemical change and physical change
- In chemical change, new substances are formed. For instance, if you burn wood, ash and charcoal is the new substance. But in physical change, new substances are not formed.
- In chemical change, the change is permanent. In physical change, the change is temporary. The state of the substance might change from solid to liquid. For example, the melting of ice.
- In physical change, the change is reversible I.e the original substance can be recovered. For example, if you put water in a freezer, it becomes ice. If you leave the ice for sometimes it will melt and become water. The original substance (water) has been recovered. But in chemical change, the change is irreversible. A ripe mango cannot become unripe no material what is done.
- In physical change, the change affects only the visible properties like the weight, size, shape. For example, if you tear a paper, the size and shape changes. Whereas in chemical change, everything changes like the boiling point, odor, aroma, taste, temperature and colour. For example, after cooking the aroma comes out different.
5. There is production of energy in chemical change: energy like heat, light and sound. For instance when fire is set on a wood, there is heat, light and sound. In physical change, there is no energy generation.
It is very important for us to understand the changes that occur around us for easy identification.