Question

How do you calculate the boiling point of a compound?

Answer 1

Hint: Boiling point, melting point, density, viscosity, refractive index, etc are different physical properties of the substances. All these properties are intensive and independent of the amount of the substance. The boiling point is the temperature when liquid is converted into vapors when its vapor pressure becomes equal to the atmospheric pressure. There is an inverse relationship between the vapor pressure and the boiling point of the liquid.

Complete step by step answer:
The process of measuring the boiling point of the compound is as follows:
- Take a small test tube containing the liquid whose boiling point to be measured.
- Tie it with the thermometer so as both lower ends of the test tube, as well as the thermometer, are at an equal level.
- Take one beaker containing concentrated sulphuric acid in it. Using the stand put a thermometer and test tube containing liquid into the burner of the concentrated sulphuric acid in such a way that acid should not enter into the test tube.
- Now, take on the capillary tube sealed at one end and place it in the test in an inverted manner. Now, heat the beaker containing sulphuric acid and stir the sulfuric with a stirrer to maintain uniform heating.
- As the temperature increases liquid gets heated. At a particular temperature, continuous bubbles arise from the open end of the capillary tube; the temperature at this point is nothing but the boiling point of the compound.
In this way, the boiling point of the compound is measured.

Note: The boiling point of the compound depends on the intermolecular forces present in the compounds. Stronger is the force of the attraction present in the particles of the compound greater is the boiling point of the compound and vice versa. If intermolecular forces increase, the vapor pressure of the compound decreases, and hence boiling point of the compound increases. Thus, by comparing the relative strength of the intermolecular forces between the compounds we can determine the relative boiling points of the compounds.