Question

Which is correct about Henry's law:
(a) The gas in contact with the liquid should behave as an ideal gas
(b) There should not be any chemical interaction between the gas and liquid
(c) The pressure applied should be high
(d) All of these

Answer 1

Hint: The quantitative connection between solubility of a gas in a liquid and pressure is given by Henry’s law. Henry’s law states that at constant temperature, the mass of a gas dissolved per unit volume of solvent is directly proportional to the pressure of the gas in equilibrium with the solution.

Complete answer:
Considering the Henry’s law, if ‘w’ represents the mass of a gas dissolved by unit volume of a solvent and ‘p’ represents the pressure of the gas I equilibrium with the solution, then
$w\,\alpha \,p$
At constant temperature.
$w\, = kp$
Where k is the proportionality constant.
The results of many studies of solubilities of gases in liquids show that Henry’s law is obeyed satisfactorily by a gas-solvent system only when
(i) the gas has a low solubility in the solvent
(ii) the pressure is not too high
(iii) the temperature is not too low
(iv) the gas does not undergo a change in its molecular state by processes such as association, dissociation or interaction with the solvent.
Considering these as favorable conditions, we can say that (b) There should not be any chemical interaction between the gas and liquid is the correct answer.

Note:
Some applications of Henry’s law include the manufacture of soft drinks, expulsion of dissolved undesired gases from solutions, explanation of biological conditions ‘bends’ and ‘anoxia’ et cetera. Bends occur in scuba divers, who dive underwater at high pressure atmosphere, whereas anoxia occurs at high altitudes due to low partial pressure of oxygen in the atmosphere.