Question

plz ans.me clearly difference between physical change and chemical change

Answer 1

Answer :

PHYSICAL CHANGE ----

As we see that when some pieces of ice are heated, they change into water. When analysed, both ice and water have the same molecules, that are H↓2O in which the combining elements, oxygen and hydrogen are combined in a fixed ratio.

Thus, on heating, ice (solid) changes into water (liquid) but the composition of the matter remains the same.

Therefore we can say that -

The process in which a substance changes its physical appearance but there is no change in its basic composition, is called physical change.

=> Characteristics of Physical change

* In a physical change no new chemical is formed.

* In a Physical change, only the physical properties like appearance, etc., of the substance change.

CHEMICAL CHANGE ---

If some sugar is heated in a dry test tube, it melts, turns red and finally black. When the resulting substance is analysed, It is found to be carbon. Thus, when sugar (White Crystals) is heated, It changes into a new substance, carbon (black). The properties of the black substance, carbon, are totally different from sugar. Also, if the resultant substance is cooled, it doesn't give back sugar, i.e., the change is irreversible.

So we can say that -

A process in which new substances are formed whose properties and composition are different from the original substance, is called a chemical change.

=> Characteristics of Chemical change

* In Chemical change, the properties of the product formed very different from the properties of the reactants,

* Chemical change is always accompanied by energy change, i.e., energy in the form of heat, light, electricity, etc., is either released or absorbed.

HOPE IT WOULD HELP YOU.