Question

When a bottle of cold drink is opened, the gas comes out with a fizz due to:
(A) Decrease in temperature
(B) Increase in pressure
(C) Decrease in pressure suddenly which results in decrease of solubility of \[{\text{C}}{{\text{O}}_{\text{2}}}\] gas in water
(D) None

Answer 1

Hint: Solubility in liquids is a concept that is key to understanding this problem. Solubility can basically be defined as the property of a solute that can be solid, liquid or gas to get dissolved in a solvent. Solubility in a liquid is dependent on various physical factors like pressure, temperature, etc.

Complete step by step solution:
According to Henry’s law, the gas that is dissolved in a liquid Is directly proportional to the partial pressure of the gas at a constant temperature.
\[P = {K_H}.C\]
Where, \[{{\text{K}}_{\text{H}}}\] is the Henry’s law constant for gases.
Cold drink bottles contain carbon dioxide which is kept at above atmospheric pressure so the solubility of carbon dioxide in an unopened cold drink bottle is very high.
When the cold drink bottle is opened dissolved carbon dioxide escapes into the atmosphere. As the gas escapes into the atmosphere the partial pressure of a gas is decreased, hence it's solubility also decreases which results in carbon dioxide bubbles to form at the surface of the drink. Hence gas comes out with a fizz.
When a bottle of cold drink is opened, the gas comes out with a fizz due to decrease in pressure suddenly which results in decrease of solubility of carbon dioxide gas in water.

Hence the correct option is (C).

Note: the solubility of the gas is proportional to its pressure above the liquid. When the pressure increases, the solubility increases and vice versa. Raoult's law states that the partial pressure of a liquid is directly proportional to the product of vapour pressure of pure component and its mole fraction in a solution. \[{P_i} = P_i^*{x_i}\]