State Henry's Law. What is the effect of temperature on the solubility of a gas in a liquid?
Henry's Law states that the solubility of a gas in a liquid is directly proportional to the pressure of the gas. If we use the mole fraction of a gas in the solution as a measure of its solubility, then it can be said that the mole fraction of gas in the solution is proportional to the partial pressure of the gas over the solution. The most commonly used form of Henry’s Law states that “the partial pressure of a gas in vapour phase (p) is directly proportional to the mole fraction of the gas (x) in the solution, i.e.
p ∝ x
p = KH x
where KH = Henry’s Law Constant
The solubility of gases is dependent on temperature. An increase in temperature results in a decrease in gas solubility in liquid, while a decrease in temperature results in an increase of gas solubility in liquid.
An increase in temperature causes an increase in kinetic energy, resulting in a more rapid motion of molecules, breaking intermolecular bonds which enable molecules to escape from the solution allowing the gases dissolved to evaporate more readily. Hence causing decrease in the solubility of gases in liquids.
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