Everyone knows that Coke is bad for their teeth. It’s sugary and acidic.
The acidity is at least partially caused by carbon dioxide (CO2) dissolved in the water, to make carbonic acid. We also know that if you pour a Coke and leave it, it fizzes away as the CO2 comes out of solution and returns to its gaseous state. Does this mean that Coke becomes less acidic if you pour it and leave it for ten minutes before drinking?
It’s also worth remembering that small changes in temperature can cause large changes in the rate of chemical reactions. If we assume our can of Coke was in the fridge at perhaps 3°C, then it will warm up in the time we leave it to fizz away. So even if it’s less acidic, the weaker, warmer acid might be able to react with our teeth faster than the stronger, cooler acid.
I am not a chemist but I want to find the answer to this thought experiment.
After a little research, it seems that dissolved CO2 (carbonic acid) is only one contributor towards the overall acidity. The most significant acid is phosphoric acid. As the CO2 comes out of solution and escapes as gas, the acidity only decreases slightly. On the other hand, when the coke warms up from 3°C to maybe 10°C as it approaches room temperature, the action of the acid will be massively accelerated.
So based on this mini experiment, Coke is worse for your teeth when it goes flat and gets warm. This, of course, neglects the action of the sugar on your teeth and all the other things we haven’t considered, so don’t blame me if you lose your teeth from drinking gallons of ice-cold Coke 😉