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CHANGE
Change is a process in which the initial and the final properties of a matter differ from each other. During a change, the difference is so specific that it can be measured by using various techniques. The revolution of earth, twinkling of stars, ripening of fruits, metabolism of body, motion of a vehicle, formation of a new compound by mixing two compounds, dissolution of sugar in water, boiling of water, evaporation of water etc are all examples of changes which occurs in nature and maybe or may not be observable to humans. All these changes are necessary for the survival of life on the earth.
The different types of changes which occur in the universe, can be categorised under different categories such as physical changes, chemical changes, biological changes, environmental changes, etc. Among these changes, physical and chemical changes are studied the most.
PHYSICAL PROPERTIES
Physical properties are the properties of substances which alters their physical factors without disturbing the chemical composition. They can be measured without changing the identity of substances. These properties can be measured simply by physical methods. These properties may or may not depend on the amount of substance. The physical properties of a substance are related to its colour, texture, hadness, density, weight, shape, melting point, boiling point, ductility, lustre, odour, state of matter etc.
CHEMICAL PROPERTIES
Chemical properties are the properties of substances which alter their chemical composition. Chemical Changes occur when one substance combines with another to form a new substance. While measuring chemical properties of a substance, its identity is altered. These properties can be measured by using chemical reactions. The chemical properties of a substance are related to its flammability, solubility, reactivity, corrosivity, combustibility, electronegativity, enthalpy of combustion, coordination number, etc.
DIFFERENCE BETWEEN PHYSICAL AND CHEMICAL CHANGES
PHYSICAL CHANGES
- In physical changes the substance’s composition remains the same but its molecule is rearranged.
- Physical change is not a permanent change.
- Physical change affects only the physical properties of substances.
- In this change, there is no formation of new products.
- It is a reversible change.
- No new bond formation or bond breaking takes place.
- Examples of physical changes – freezing of water, melting of wax, melting of ice, chopping of wood, etc.
CHEMICAL CHANGES
- In chemical changes the substance’s molecular composition is changed and due to the formation of new products is possible.
- Chemical changes are a permanent change.
- Chemical changes affect the both chemical and physical properties of substances.
- In this change there is formation of new products.
- It is a non reversible change.
- New bond formation or bond breaking takes place.
- Examples of chemical changes – combustion of wood, rotting of fruits, rusting of iron, digestion etc.
IDENTIFICATION OF PHYSICAL AND CHEMICAL CHANGES
Physical and chemical changes can be measured by a number of methods. Few of the methods of identification of physical and chemical changes are as follows –
- IDENTIFICATION OF PHYSICAL CHANGES – Physical changes can be measured by –
(1) Measuring the change in the shape of a substance
(2) Measuring the melting and boiling point of a substance
(3) Measuring the mass of a substance
(4) Observing the odour of the substance
- IDENTIFICATION OF CHEMICAL CHANGES – Chemical changes can be measured by –
(1) Determining the solubility of a substance in different chemical compounds
(2) Determining the oxidation state of a substance
(3) Determining the chemical composition of a substance
(4) Determining the strength of a chemical compound
CONCLUSION
Physical and Chemical changes are considered to be essential for the production of new substances. A change which alters the physical properties of a substance is called physical change. A change which alters the chemical properties of a substance is called physical change. There are a lot of examples in our daily life that happen due to these changes like boiling, freezing, digestion etc. Physical and chemical changes occur in chemical reactions, in changing the state of substance. Our life processes depend on these changes, and these changes form the basis of our life. In the absence of these changes, the transformation and conservation of energy is not possible.
