# What makes Coke acidic?

What makes Coke and other soft drinks acidic? These drinks are carbonated, so a freshly-opened can should have a lot of dissolved carbonic acid, but the ingredients also lists phosphoric acid. Would flat Coke be significantly less acidic than carbonated Coke?

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This is an interesting question. Off-handedly, I'd say it was mainly the phosphoric acid (which is added intentionally for "bite"), but if someone sits down and calculates given the pressure of the carbonation and the concentration of phosphoric acid, it would be a great answer. – jonsca Jan 1 at 20:59

Just shake a coke, or heat it and see how much of the acidity is gone. It is the part that is due to $\ce{CO2}$.