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how to identify a solid, liquid and gas by looking at their boiling and melting points

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mattlimey | Student, Grade 11 | Honors

Posted March 23, 2013 at 6:41 AM via web

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how to identify a solid, liquid and gas by looking at their boiling and melting points

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jeew-m | College Teacher | (Level 1) Educator Emeritus

Posted March 23, 2013 at 7:13 AM (Answer #1)

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Melting point and boiling point are temperatures. The melting point and boiling point is dependant on pressure as well. Usually these temperatures are expressed related to the standard pressure of 1 atm and room temperature of 25C. Here onwards my explanations are based on standard pressure.

Melting Point

This is the temperature at which a solid become a liquid. When we increase the temperature of a solid it will become liquid at its melting point. At low temperatures than melting point the substance remain as a solid. Then from melting point temperature to boiling point the substance will remain as a liquid.

 

Boiling point

This is the temperature at which a liquid become a gas. When we increase the temperature of a liquid it will become gas at its boiling point. Boiling point is greater than melting point. After the boiling point the substance will remain as gas.

 

Now let us consider a substance where melting point is 50C and boiling point is 100C. So at room temperature or at 25C it will be a solid. Because its melting point is 50C.

 

Let us again consider a substance where melting point is 10C and boiling point is 50C. Not at room temperature it will be a liquid.

 

For a substance which is having melting point -20C and boiling point -5C at room temperature it will remain as a gas because room temperature is above boiling point.

 

For your example;

Melting point  = 0C

Boiling point  = 108C

 

At room temperature the substance is at a temperature between melting point and boiling point. So it Will be a liquid.

So the phase of a substance liquid gas or solid depends on their melting points, boiling points, room temperature and pressure.

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