Difference Between Physical And Chemical Changes

What are the main differences between physical and chemical change ? & some examples please.

Expert Answers

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There are marked differences between physical and chemical changes.

Physical changes, typically, refer to changes in size, shape, texture, temperature, density, viscosity, etc. common examples include, change in volume of a material upon heating. Think what happens to a rubber ball that is heated or how welding is done (metal melts and solidifies when cooled). Think about the increase in viscosity of vehicle fuel during summer months (as compared to winter), thus leading to higher fuel efficiency (more miles per gallon of fuel). Similar is observed with honey, between summer and winter.

Physical changes do not lead to new substances being formed, which is a typical property of chemical changes. Here new bonds are formed between molecules, leading to new substances. Think about burning of leaves  leading to generation of gases or how plants grow and lead to fruits. Some other examples include rusting of iron, burning of oil (in cooking, vehicle operation, etc.), rotting of fruits, etc.

Pls. note that many of these changes are reversible, both physical and chemical. Examples are melting and re-solidification of metals upon heating and cooling. Similarly, chemical compounds may be formed reversibly (although not that easily manifested to casual observer). Chemical reversibility or cycling is more easily observed with nutrient cycling in nature. A common example is wwater cycle in nature. 

good luck.

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