Why does your soft drink fizz when opened? - SALIENT TIMES ONLINE

Why does your soft drink fizz when opened?

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By Omoyeni Adebola Daniel


Whenever you open a bottle of soft drink, beer or Champagne, do you notice gas bubbles rushing out of the drink?


Sometimes the fizz can be so great that it causes the drink to splatter on your body, stigmatizing the newly bought Balenciaga outfit you wear on your birthday. Then you wonder, “why do soft drinks fizz?” The answer is just chemistry in action!

In most cases, external pressure has no effect on the solubility of solids and liquids but has a major effect on the solubility of gases.

 According to Henry’s law,the solubility of a gas increases with increase in partial pressure.

This means that the amount of a gas dissolved in a solvent increases with increase in pressure. Before the beverage bottle is sealed, it is pressurized with a mixture of air and carbon dioxide (gas) saturated with water vapor.

Because of this high pressure, the amount of carbon dioxide dissolved in the soft drink is many times greater than would normally dissolve under normal atmospheric conditions.

Once the cap is opened, the pressurized gases escape so that the partial pressure of carbon dioxide can return to its normal atmospheric partial pressure of 0.03atm.

Consequently, the excess dissolved carbon dioxide rushes out of the drink in form of bubbles which causes the drink to splatter on your body.

Moreover, when next you buy a carbonated drink, Chemist Adebola advises you to open the cap partially first and wait few seconds till the gas pressure normalizes before opening it totally, to prevent it from splattering on your body.