Question

when we consider the change of liquid to solid we are describing the structure of substance?

Answer 1

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• For most substances, the melting and freezing points are the same temperature; however, certain substances possess different solid-liquid transition temperatures.

• Most liquids freeze by crystallization, the formation of a crystalline solid from the uniform liquid.

• Freezing is almost always an exothermic process, meaning that as liquid changes into solid, heat is released.

• The energy released upon freezing, known as the enthalpy of fusion, is a latent heat, and is exactly the same as the energy required to melt the same amount of the solid.

Freezing, or solidification, is a phase transition in which a liquid turns into a solid when its temperature is lowered to or below its freezing point. All known liquids, except helium, freeze when the temperature is low enough. (Liquid helium remains a liquid at atmospheric pressure even at absolute zero, and can be solidified only under higher pressure.)

For most substances, the melting and freezing points are the same temperature; however, certain substances possess different solid-liquid transition temperatures. For example, agar displays a hysteresis in its melting and freezing temperatures: it melts at 85 °C (185 °F) and solidifies between 31 °C and 40 °C (89.6 °F to 104 °F).

Most liquids freeze by crystallization, the formation of a crystalline solid from the uniform liquid.