Question

[MULTIPLE CHOICE QUESTION]: Carbon dioxide gas in most soluble in water under conditions of?

1) high pressure and low temperature
2) high pressure and high temperature
3) low pressure and low temperature
4) low pressure and high temperature

Answer 1

Answer is:
1) high pressure and low temperature.

Explanation:

Let's explain each parameter or change separately.

A) Regarding change in pressure and its effect on the solubility of a gas in a liquid, this can be explained by Henry's law which states that:
"At a constant temperature, the amount of a given gas that dissolves in a given type and volume of liquid is directly proportional to the partial pressure of that gas in equilibrium with that liquid." An equivalent way of stating the law is that the solubility of a gas in a liquid is directly proportional to the partial pressure of the gas above the liquid:
C=kPgas
where C: the solubility of a gas at a fixed temperature in a particular solvent.
k: Henry's law constant.
Pgas: the partial pressure of the gas

So, it's obvious now that an increase in pressure will increase the solubility of a gas in a liquid.

B) Regarding change in temperature , increasing temperature will result in elevation in the kinetic energy of the system, this energy does affect the motion of the molecules to be fast. Thus, intermolecular forces between gas molecules will be weak, that results in the escape of the gas molecules from the solution.
So, it's obvious now that decreasing temperature will increase the solubility of a gas in a liquid.

This link may help a lot.
http://chemistry.elmhurst.edu/vchembook/174temppres.html