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?

Short answer

(a) Carbonated beverages must be stored in sealed containers to maintain a pressurized environment, which helps keep CO2 gas dissolved in the liquid. If the container was not sealed, CO2 gas would escape, and the beverage would lose its carbonation and become flat. (b) After opening, a carbonated beverage maintains more carbonation when refrigerated because the lower temperature increases CO2 gas solubility in the liquid, making it less likely to escape. In contrast, at room temperature, CO2 solubility is lower, causing the gas to escape more quickly and decrease carbonation levels.

Step-by-step solution

Understanding Carbonation

Carbonation is the process of dissolving carbon dioxide (CO2) gas in a liquid, usually water. When CO2 dissolves in water, it forms carbonic acid, which gives carbonated beverages their characteristic fizz and taste. The CO2 needs to be kept in the liquid to maintain carbonation, and factors such as temperature and pressure play a significant role in this process.

Sealed Containers for Carbonated Beverages

Carbonated beverages must be stored in sealed containers because the CO2 gas that provides the fizz is constantly trying to escape the liquid. Sealed containers maintain a small space above the liquid full of pressurized CO2 gas, which helps to keep the CO2 dissolved in the liquid. If the container was not sealed, the CO2 gas would escape into the air, and the beverage would lose its carbonation and become flat.

Factors Affecting Gas Solubility

The solubility of gases in liquids is influenced by temperature and pressure. According to the principles of chemistry, an increase in pressure increases the solubility of a gas in a liquid and an increase in temperature decreases the solubility of a gas in a liquid.

Effect of Refrigeration on Carbonated Beverages

Once a carbonated beverage has been opened, some of the CO2 gas escapes from the liquid, which causes a decrease in carbonation. When a carbonated beverage is refrigerated, the temperature of the beverage is lowered, which increases the solubility of CO2 gas in the liquid. As a result, the beverage maintains more carbonation as the remaining dissolved CO2 is less likely to escape from the liquid at low temperatures. On the other hand, at room temperature, the solubility of CO2 is lower, so the gas tends to escape more quickly, decreasing the carbonation level in the beverage. To summarize, carbonated beverages should be stored in sealed containers to maintain a pressurized environment that helps keep CO2 gas dissolved in the liquid. Once opened, refrigerating the beverage helps maintain more carbonation by increasing the solubility of CO2 gas in the liquid compared to room temperature conditions.