Problem 31 - Chemistry: The Central Science

Question

(a) Explain why carbonated beverages must be stored in sealed containers. (b) Once the beverage has been opened, why does it maintain more carbonation when refrigerated than at room temperature?

Step-by-Step Solution

Answer

(a) Carbonated beverages must be stored in sealed containers to maintain the pressure inside the container, which prevents the CO2 from escaping the liquid and preserves the carbonation. (b) Once opened, the beverage maintains more carbonation when refrigerated because the solubility of CO2 decreases with increasing temperature. In lower temperatures, CO2 remains more soluble in the liquid, maintaining carbonation and keeping the beverage fizzy for a longer duration compared to being stored at room temperature.

Step 1: Concept of Carbonation

Carbonation is the process of dissolving carbon dioxide (CO2) gas into a liquid, such as water or a beverage, under pressure. When the pressure is reduced, the CO2 comes out of the solution, forming bubbles. Carbonated beverages contain dissolved CO2, which gives them their fizzy and bubbly nature.

Step 2: Part (a): Sealed Containers

Carbonated beverages need to be stored in sealed containers to maintain the pressure inside the container. The pressure prevents the CO2 from escaping the liquid and preserves the beverage's carbonation. When the container is opened, the pressure is reduced, and the CO2 starts leaving the solution, forming bubbles. So, to retain the carbonation and keep the beverage fizzy, it is essential to store it in a sealed container.

Step 3: Part (b): Effect of Temperature on Carbonation

When a carbonated beverage has been opened, its ability to maintain carbonation depends on temperature. According to Henry's Law, the solubility of gas in a liquid is directly proportional to the partial pressure of the gas above the liquid. The solubility of CO2 decreases with increasing temperature, making it easier for CO2 to escape from the solution. When a carbonated beverage is kept at room temperature, CO2 is more likely to leave the liquid and form bubbles. On the other hand, when the beverage is refrigerated, the CO2 remains more soluble in the liquid due to the reduced temperature. This maintains the carbonation, keeping the beverage fizzy for a longer duration as compared to being stored at room temperature.