Why use carbon dioxide for fizzy drinks?

We don't use oxygen for this because oxygen is very good at oxidising things, and will make them go off. This will make your drink taste nasty. Carbon dioxide is basically a neutral chemical; it doesn't react with much, so it shouldn't make your drink taste bad.Carbon dioxide is also acidic and when it's dissolved it makes carbonic acid, which gives a nice, lemony, sparkly taste in your mouth.