Chemistry

Ebulioscopy


THE ebullioscopy It is a colligative property that causes a liquid to rise in temperature when a non-volatile, nonionic solute is added to it.

The temperature at which boiling of the solvent in a nonvolatile solute solution is always higher than the boiling point of the pure solvent (under the same pressure).

This is because water, for example, will only boil again if it receives enough energy to bring its vapor pressure back to the outside (atmospheric) pressure, which will happen at a temperature above 100 ° C. Example:

Pure water: M.W. = 100 ° C
Sugar water: P.E. greater than 100 ° C

See the following table for different solutions of sucrose in water and P.E.

Amount of sucrose material (per kg water)

P.E. Pure Water at 1atm

P.E. water in 1atm solution

0,01

100

100,01

0,2

100

100,10

0,8

100

100,42

Note that the more dissolved particles in the solution, the higher the boiling temperature.

The larger the amount of particles in a solution, the higher its P.E.

Phase diagram and the triple point

The transformation of each physical state has a name. Watch:

 

There is a graph showing the boiling temperature and solidification temperature curves of any substance as a function of vapor pressure.

These curves coincide at a specific point in each substance.

The variation curves of boiling and solidification temperatures of water as a function of vapor pressure coincide at the point where the pressure is 4,579mmHg and the temperature is 0,0098 ° C.

This coordinate represents the triple point of water and the phase balance.

This means that the substance can be found at this exact point in the curve in the three physical states at once: solid, liquid and gas.

Phase Balance: