Interconvertibility of the States of Matter


 
 
Concept Explanation
 

Interconvertibility of the States of Matter

Interconvertibility of the States of Matter:

All the three states of matter are interconvertible i.e. matter can be changed from one state to another.For example: ordinary water. When water is cooled at 0°C, it is transformed into ice (solid). Heated to 100°C, it begins to boil and goes into the gaseous state (vapours). On cooling, water vapour gradually passes into the liquid state and finally to the solid state (ice).

Explanation: 

  • Heating increases kinetic energy of the particles of the solid (ice). As a result, the vibration of the particles about their mean position of rest is also enhanced. The heat energy which is supplied is consumed in overcoming the intermolecular forces of attraction between the particles. The particles now move freely with increased speeds. This results in melting of ice.
  • The temperature at which solid goes into liquid state at atmospheric pressure is known as melting point of solid. The melting point of ice is 0°C (or 273.15 K). The conversion of a solid into liquid is called fusion of the solid. The heat supplied to the ice does not increase its temperature as the heat is used to overcome the intermolecular forces of attraction between the particles. This heat, thus, remains stored in the contents of the beaker and is called the latent heat of fusion.
  • The amount of heat energy absorbed when 1kg of a substance changes from solid to liquid at its melting point is called latent heat of fusion of the solid. On further heating, the particles of the liquid gain more energy and begin to vibrate more vigorously. They become so energetic that they break the intermolecular forces of attraction. They are now free to leave the liquid and go into the gaseous state. The liquid then begins to boil. The temperature at which a liquid is converted into gas or vapour is known as the boiling point of the liquid.
  • At normal pressure (1 atm) the boiling point of water is 100°C (373.15 K). During boiling, the temperature of a liquid does not rise despite heating. Instead, the supplied heat energy goes to raise the kinetic energy of the particles. When the particles acquire enough energy, they overcome the attractive forces of other particles and go into vapour state. As the heat energy received by the liquid remains hidden inside the bulk of liquid, it is called the latent heat of vaporization.

  • The amount of heat energy absorbed when 1kg of a substance changes from liquid to vapour at its boiling point is called latent heat of vaporization of liquid. On cooling, reverse process occurs i.e. gas or vapour when cooled is converted into liquid. The process by which the change in state from gaseous to liquid takes place is called condensation or liquefaction. When the liquid is further cooled, it is transformed into solid.
  • The temperature at which the change in state from liquid to solid takes place is called the freezing point of the liquid and the process by which such a change takes place is called freezing.
  • Sample Questions
    (More Questions for each concept available in Login)
    Question : 1

    What term is used to describe the phase change of a solid to a liquid?

    Right Option : B
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    Explanation
    Question : 2

    The process for the change of a solid directly into its vapour is called ____________________

    Right Option : D
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    Explanation
    Question : 3

    Which of the following are correct :

    (a) The temperature at which the change in state from liquid to solid takes place is called the freezing point of the liquid.

    (b) At normal pressure (1 atm) the boiling point of water is 100°C (373.15 K).

    (c) On cooling, water vapour gradually passes into the liquid state and finally to the solid state (ice).

    Right Option : D
    View Explanation
    Explanation
     
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