Carbonic acid (H2CO3) — the chemical species formed from carbon dioxide dissolved in water; a chemistry term.
二酸化炭素を溶かすと水中に炭酸が生成される。
When carbon dioxide dissolves, carbonic acid is formed in the water.
Carbonated water; carbonated drink — fizzy water or soft drinks containing dissolved carbon dioxide.
暑い日には炭酸の入った飲み物が飲みたくなる。
On hot days I want to drink something fizzy.
コーラの炭酸が抜けてしまって、味が落ちた。
The cola went flat and lost its taste.
炭酸水は料理やカクテルにもよく使われる。
Carbonated water is often used in cooking and cocktails.
Colloquially used to refer to baking soda or carbonates; often written in kana as タンサン (e.g., sodium bicarbonate).
掃除にはタンサン（炭酸水素ナトリウム）を使うと油汚れが落ちやすい。
Using tanzan (sodium bicarbonate) for cleaning makes it easier to remove grease.
レシピには『タンサン小さじ1』と書いてあったので重曹を入れた。
The recipe said '1 teaspoon of tanzan', so I added baking soda.