4. Liquid to Solid Change : Freezing
When water is cooled (by lowering its temperature by keeping in the freezer compartment of a refrigerator), it changes into solid 'ice'. The process of changing a liquid into a solid by cooling, is called freezing. For example, when water is cooled, it gets converted into a solid called "ice". This is called freezing of water. Freezing means solidification. When water freezes to form ice, then there is a change from liquid state to solid state. Please note that freezing is the reverse of melting. So, the freezing point of a liquid is the same as the melting point of its solid form. For example, the melting point of ice is 0°C, so the freezing point of water is also 0°C. A change of state (liquid to solid) occurs during freezing. This happens as follows.
When a liquid is cooled (by lowering its temperature), its particles lose energy due to which they move slowly. If the liquid is cooled enough (up to its freezing point), its each particle stops moving and vibrates about a fixed position. At this stage the liquid freezes and becomes a solid.
From the above discussion we conclude that the state of matter can be changed by changing the temperature (by heating or cooling). For example, when a solid is heated, it melts to form a liquid. And when the liquid is heated further, it boils to form a gas. These changes can be easily reversed. For example, when a gas is cooled, it condenses to form a liquid. And when a liquid is cooled further, it freezes (or solidifies) to form a solid. The conversion of matter from one physical state to another can be shown as follows :
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3. 2. Liquid to Gas Change : Boiling (or Vaporisation)
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4. 2. Latent Heat of Vaporisation (Liquid to Gas Change)
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5. Classification Of Matter As Solids, Liquids And Gases
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6. Effect of 'Heating' and 'Cooling' on a Saturated Solution
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9. Why Solids, Liquids and Gases Have Different Properties
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14. 2. The Particles of Matter have Spaces Between Them
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15. 1. Solid to Liquid Change : Melting
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16. 3. Gas to Liquid Change : Condensation
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20. 1. Latent Heat of Fusion (Solid to Liquid Change)
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24. 1. The Particles of Matter are Very, Very Small
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26. 4. The Particles of Matter Attract Each Other
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28. 3. The Particles of Matter are Constantly Moving
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29. Characteristics of Particles of Matter
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30. 4. Liquid to Solid Change : Freezing
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31. Two More States of Matter : Plasma and Bose-Einstein Condensate
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38. The Common Unit Of Temperature and Si Unit Of Temperatre
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39. To Show That Solids and Liquids Cannot be Compressed but Gases Can be Compressed Easily
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44. To Show that Liquids do not have a Fixed Shape but they have a Fixed Volume
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45. To Show the Presence of Water Vapour in Air
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49. Gases Can be Liquefied by Applying Pressure and Lowering Temperature
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50. To Show that Gases do not have a Fixed Shape or a Fixed Volume
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