1. Solid to Liquid Change : Melting
If we heat ice, it changes into water. In this case, solid ice changes into liquid water, so a change of state has taken place. The process in which a solid substance changes into a liquid on heating, is called melting (or fusion). So, when ice changes into water on heating, it is called melting of ice (or fusion of ice). A change of state takes place during melting (or fusion). The melting of a solid substance takes place at a fixed temperature. The temperature at which a solid substance melts and changes into a liquid at atmospheric pressure, is called melting point of the substance. For example, the ice melts at a temperature of 0°C to form liquid water, so the melting point of ice is 0°C (zero degree Celsius).At melting point, ice changes its state from solid to liquid.
Different solids have different melting points. For example, the melting point of ice is 0°C; the melting point of wax is 63°C whereas the melting point of iron is 1535°C. The melting point of a solid is a measure of the force of attraction between its particles (atoms or molecules). Higher the melting point of a solid substance, greater will be the force of attraction between its particles. For example, the melting point of iron metal is very high (1535°C) which tells us that the force of attraction between the particles of iron is very strong. We will now describe how a solid changes into a liquid on heating.
When a solid is heated sufficiently, it changes its physical state and becomes a liquid. This happens as follows : When a solid substance is heated, the heat energy makes its particles vibrate more vigorously. At the melting point, the particles of a solid have sufficient kinetic energy to overcome the strong forces of attraction holding them in fixed positions and break to form small groups of particles. And the solid melts to form a liquid.
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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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