The Role of Dissolved Carbon Dioxide
The fizz in carbonated drinks like soda, sparkling water, or beer is caused by dissolved carbon dioxide (CO2) gas. Under high pressure during bottling, CO2 gas is forced into the liquid, where it dissolves, forming a supersaturated solution. This process is known as carbonation.
Pressure Release and Bubble Formation
When you open a carbonated drink, the pressure above the liquid is released. This sudden drop in pressure significantly reduces the solubility of CO2 in the liquid. As a result, the dissolved CO2 can no longer remain in solution and rapidly escapes as gas bubbles, creating the characteristic fizz.
A Practical Example: Opening a Soda Can
Imagine a freshly opened soda can. The moment the tab is pulled, the distinctive hiss is the sound of pressurized CO2 escaping. Tiny bubbles begin to form on the walls of the container and rise to the surface, illustrating the CO2 coming out of solution as its solubility decreases at atmospheric pressure.
Factors Affecting Fizz
Several factors influence the amount and duration of fizz, including temperature (colder liquids hold more dissolved gas), the initial carbonation pressure, and the presence of nucleation sites (tiny imperfections or impurities on the glass surface) which provide starting points for bubble formation.