Question

A process is being developed to produce carbonated beverages. As part of this process, a packed-bed absorption tower will be used to dissolve carbon dioxide, CO2, gas into water. Pure mountain spring water, containing no dissolved CO2 enters the top of the column at a molar flow rate of 5.0 kgmole/min. Pure CO2 gas at 2.0 atm is also fed to the top of the tower at a flow rate of 1.0 kgmole/min. As the liquid flows down the tower, CO2 gas absorbs into the water, and the dissolved CO2 concentration increases down the length of the bed. The carbonated water and the unused CO2 gas exit the bottom of the tower. The absorption process ____.

a) Removes CO2 from water
b) Adds CO2 to water
c) Filters CO2
d) Produces pure CO2

Answer 1

The absorption process described involves adding CO₂ to water to create carbonated beverages. This is achieved through high-pressure exposure of beverages to CO₂ gas, resulting in the dissolution and retention of a high CO₂ concentration when the drinks are sealed. Option b is the answer.

Step-by-step explanation:

The absorption process in the production of carbonated beverages involves adding carbon dioxide (CO₂) to water. During this process, CO₂ gas is fed into a packed-bed absorption tower where it dissolves into the water to create the carbonated water. The gas solubility in water increases under high pressure, which is why manufacturers expose beverages to high pressures of CO₂ gas. After the carbonation process, beverages are sealed to trap the CO₂ under pressure, ensuring a high concentration of dissolved gas.

When a carbonated beverage bottle is later opened, the pressure of the CO₂ gas above the liquid decreases, leading to a reduction in solubility and the release of CO₂ gas from the beverage, which we observe as fizz. If left open, the beverage eventually becomes "flat" as more CO₂ escapes and the concentration of dissolved gas decreases to its equilibrium value.