Thursday, May 29, 2014

Understand the relationship between temperature and solubility of gases

Taken from http://www.elmhurst.edu/~chm/vchembook/174temppres.html

"The variation of solubility for a gas with temperature can be determined by examining the graphic on the bottom.


As the temperature increases, the solubility of a gas decrease as shown by the downward trend in the graph .

More gas is present in a solution with a lower temperature compared to a solution with a higher temperature.

The reason for this gas solubility relationship with temperature is very similar to the reason that vapor pressure increases with temperature. Increased temperature causes an increase in kinetic energy. The higher kinetic energy causes more motion in molecules which break intermolecular bonds and escape from solution.

This gas solubility relationship can be remembered if you think about what happens to a "soda pop" as it stands around for awhile at room temperature. The taste is very "flat" since more of the "tangy" carbon dioxide bubbles have escaped. Boiled water also tastes "flat" because all of the oxygen gas has been removed by heating."

Another great explanation by Vibs:

As temperature increases the mean kinetic energy of all particles present increase, allowing for the gases dissolved to evaporate more readily, as they are in a greater state of vibratory motion - that is they are present in a more gaseous form. Phase is determined by the extent of motion of particles, which is determined by the intermolecular forces acting between molecules. An increase in temperature will also increase the motion of dissolved particles by weakening the forces acting between the solute and solvent. This allows the dissolved gases to evaporate out of solution. Hence an increase in temperature corresponds to a decrease in the solubility of gases in liquids. Hope it helps

http://wiki.answers.com/Q/Why_does_an_increase_in_temperature_decrease_the_solubility_of_gases_in_liquids

The bold part is the most important part I feel.

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