# How does carbonic acid affect pH?

It lowers $p H$ slightly.........
Carbonic acid is ${H}_{2} C {O}_{3}$ or is perhaps better represented as hydrated carbon dioxide, ${H}_{2} O \cdot C {O}_{2}$. Carbonic acid can be deprotonated to give ${\left[H C {O}_{3}\right]}^{-}$.