2
$\begingroup$

I did an experiment for my chemistry class and did a control with sparkling water and the pH increased by a significant amount, but when done with sodas like cream soda, coke, or 7 Up, the pH change is so minimal that I can't say that there is a significant change in the pH level. Why do the pH level of these sodas to stay the same when they lose their fizz?

$\endgroup$
1
  • 1
    $\begingroup$ The sodas have other acids with pKa's lower than that of carbonic acid. $\endgroup$
    – MaxW
    Jun 25, 2018 at 20:11

1 Answer 1

2
$\begingroup$

In addition to fizz (carbonic acid), Coca-Cola contains phosphoric acid (for an additional tangy taste). According to this leaflet put out by Coca-Cola, a 250 mL can of Coca-Cola contains 43 mg of phosphorus. With some quick calculation, you can find that this translates to $\ce{5.5538 \times 10^{-3} M}$ $\ce{H3PO4}$, which would have a pH of approximately 2.44. Pretty acidic! The other sodas are sure to contain other acids as well.

$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge that you have read and understand our privacy policy and code of conduct.

Not the answer you're looking for? Browse other questions tagged or ask your own question.