eli5: Why is co2 the gas used to pressurize drinks. Why can’t something like nitrogen or atmosphere air be used.
In: 2772
Nitrogen *is* used in place of CO2. Nitro stout beer, nitro cold brew coffee, and nitro Pepsi is a thing (nitro Pepsi is basically just pre-flattened Pepsi, 2/10 would not recommend).
The important fact here… “soft” drinks were created and artificially inflated with CO2 to replicate the natural carbonization that occurs as a waste product when yeast breaks down sugars into alcohol.
It’s supposed to replicate a naturally fermented and thus alcoholic carbonated beverage
Some people are forgetting that ethanol plants make tonnes of CO2 as a byproduct.
Worked for a company ( Air Products ) that refined/purified the CO2 for use in beverages for carbonation. It’s abundance and lack of all most all flavor/smells makes it an easy choice. It is also very easy to transport, storage , and it’s temperature range has many other food industry benefits ( dry ice , very effective for meat freezing are the bigger ones. Slaughter houses were our biggest customers in Iowa and Nebraska )
Something I didn’t know, is we’d deliver liquid CO2 water treatment plants. They’d inject a bit of it into the water supply for a reason I never looked up
A lot of answers are pretty spot on. However I think you ask why we can’t use something else to create a “fizzy” drink.
CO2 gas is very soluble in water (compared to other gasses) while still keeping it safe to drink. CO2 under (relatively) low pressure creates carbonic acid. Carbonic acid (H2CO3) creates a slight acidic flavour in your drink and due to its solubility it slowly gets released as CO2 gas.
If we were to take nitrogen (a notoriously stable molecule) we would have to put in a lot of effort to split the nitrogen atoms to create a bond with water. Nitrogen has a triple bond, so it would only come apart under extreme circumstances (it would also most likely create some nitric acids, which are not very healthy).
Oxygen is a very reactive molecule so we, theoretically, could use that. However, if we use oxygen in too high concentrations it would actually react with water forming peroxide (H2O2) which is toxic.
So in short: we use co2 gas because its cheap, easy to manage and non toxic
Just adding to the other answers here– Carbon Dioxide is highly compressible compared to nitrogen and air. A large canister of CO2 will hold more compressed (liquefied) gas compared to others. CO2 can be compressed and stored as a liquid under ordinary temperatures, unlike liquid nitrogen which requires expensive cooling.
The per-unit cost to the businesses that provide the soda, and the cost to the consumers, is less and therefore improves the popularity of the product.
Incidentally: the high compressibility and low temperature requirements of CO2 is being investigated as a means of grid-scale energy storage, similar to a battery: https://electrek.co/2022/06/28/worlds-first-co2-battery/
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