States Of Matter

Introduction

               We are living in a world where there are so many things exist. A substance exists in a state which we call state of matter. Matter has certain characteristics. The characteristic of matter is matter occupies space, has volume and weight. There is difference in properties of different types of matter and a matter may exist in a state of solid, liquid or gas.

Properties of matter

               Every matter contains certain properties. A substance which is in solid state contains the properties of solid. Besides this, it consists of the properties of the matter of which it is made. A solid substance contains molecules in compact form and the intermolecular space, the gap between two molecules, is very less. Whereas in case of liquids inter-molecular space is more. Intermolecular space is still more in gas. Whatever may be the state, matter occupies space.

               When a solid is heated, generally it turns into liquid. A liquid under heat turns into gas. This can be understood from following experiment. But, there are some substances due to heat, from solid directly turn into gas and by cooling they turn into solid. Conversion of a solid into liquid by heating is called melting or fusion. Ice melts on heating. Conversion of a solid is called solidification. When water is cooled very much, below 0C, it turns into solid.

Experiment: when a liquid is heated, generally it turns into gas. For example, steam. When water is heated it turns into vapor state which we call gaseous state. Thus, conversion of liquid into gas is called vaporization. The steam, if cooled, will turn into liquid. Thus gas may be turned into liquid. This is called condensation.

               There are some substances which turn into gaseous state when heat is given and they turn into solid under cooling. Thus, a solid when turns directly into gaseous state and converts into solid after cooling, is called sublimation. Camphor behaves like this.

Change of state

               Change of state is called the conversion from one state into other. There are different ways by which change in state takes place.

1.A solid substance which converts into liquid by heating is called fusion or melting. And such a conversion takes place at a particular temperature called melting point.

2.A liquid substance turns into vapor due to heat. Such a conversion of liquid into vapor or gaseous state is known as vaporization. For example, water converts into vapor due to heat.

3.A substance which is in vapor state, i.e., gaseous state, converts into liquid after cooling. The conversion of gas into liquid is known as liquefication or condensation. When water vapor is cooled, it turns into water again.

4.A liquid can be turned into solid after cooling very much.  Such a conversion of a liquid into solid due to cooling is known as solidification. After cooling very much, water turns into solid ice.