Question

Which law relates solubility of solvents with pressure?

• A. Hess’ law
• B. Henry’s law
• C. Charles’ Law
• D. Boyle’s law

Hint:

Henry's law is fundamental in understanding how gases dissolve in liquids under pressure, such as in soda cans.

Answer 1

The Correct Option is B

• Option 1: Hess’ law - Hess' law relates to the heat changes in chemical reactions, not to the solubility of solvents. Therefore, this is not the correct answer.
• Option 2: Henry’s law - This is the correct answer. Henry’s Law states that the solubility of a gas in a liquid is directly proportional to the pressure of the gas above the liquid, provided the temperature is constant.
• Option 3: Charles’ Law - Charles' Law relates to the relationship between the volume and temperature of a gas, not the solubility of solvents. Therefore, this is not the correct answer.
• Option 4: Boyle’s law - Boyle’s law describes the relationship between the pressure and volume of a gas at constant temperature, but it does not describe the solubility of solvents. Hence, this is not the correct answer.

Explanation:

Henry's Law is the correct law that describes the relationship between the solubility of gases in solvents and pressure. According to Henry’s Law, the solubility of a gas increases as the pressure of the gas above the solvent increases, assuming temperature remains constant.

Answer 2

Instead of judging these one at a time, it helps to notice that three of the four are gas laws relating pressure, volume, or temperature to each other, while only one of them deals with a gas dissolving into a liquid.

1. Hess' law: This belongs to thermochemistry, and it says that the total enthalpy change of a reaction is the same regardless of the path taken, no matter how many steps it is broken into. It has nothing to do with solubility or pressure.
2. Henry's law: This is the one law in the list that specifically connects a gas dissolving in a liquid to the pressure of that gas above the liquid. It belongs to the category of gas-in-liquid solubility, which is exactly what the question asks about.
3. Charles' Law: This connects the volume of a fixed amount of gas to its temperature at constant pressure. It stays within the pure gas-law category and never involves a liquid solvent.
4. Boyle's law: This connects the pressure and volume of a fixed amount of gas at constant temperature. Like Charles' law, it is about a gas on its own, not a gas dissolving into a liquid.

Hess', Charles', and Boyle's laws all describe gases or reactions without reference to solubility, leaving Henry's law as the only one that fits.

So the correct answer is Henry's law.