What method should I use to find the pH of 7up without losing the carbonic acid?
I don’t see why you couldn’t pour it into a container and simply measure the pH with a pH meter. It’s not like the carbonic acid all disappears in a minute. You could pour it into a beaker or flask and cover all but the electrode with plastic wrap to minimize loss of CO2. You could standardize the electrode, pour the 7-Up into that container with the rinsed electrode already in it, measure pH as a function of time, and extrapolate back to time zero. And you might be able to get the information from the manufacturer, to see how closely your experimental results correspond to the pH of the product at the time it’s canned/bottled.
