Chemistry. Which is more acid, flat coke or regular ?

The_Real_Clipper
The_Real_Clipper used Ask the Experts™
on
I found various and opposed answers to this question on the web. What would be the respective pH of flat coke compared to a brand new coke bottle freshly opened ?

I would think the pH would raise as the carbonic acid evaporates. Less CO2 so less acidic.

Unless what makes Coke acid is not the carbonic acid but the phosphoric acid which doesn't evaporate ?

Any thoughts (or even better pH-meter results) ?

Thanks
Comment
Watch Question

Do more with

Expert Office
EXPERT OFFICE® is a registered trademark of EXPERTS EXCHANGE®

Commented:
This sounds like homework...

Author

Commented:
Now that's a useful comment pal, what I am asking for is a proper chemistry answer, not a mom's advice.

Commented:
Well we're not allowed to help people with their homework....it's in the rules dickhead. Prove to us that it isn't homework.
CompTIA Network+

Prepare for the CompTIA Network+ exam by learning how to troubleshoot, configure, and manage both wired and wireless networks.

Author

Commented:
First, insulting people is forbidden by the rules as well, smartass.

Now if you would have checked my profile and for instance my answer on Q_21146410 you might have found by yourself that I'm not a kid. I ask this question because we had a debate with a friend on whether flat coke is better for the stomach than plain carbonated coke. I don't have a ph-Meter and I'm not keen to cook a red cabbage to find out, that's it.

Commented:
Well, I know that anything with Carbonic Acid is terrible for "our insides"...so I would guess that it is more acidic....although i've seen people putting metal in a glass of coke, flat or otherwise, and it corrodes it...so maybe there isn't much difference.
The easiest and most authoritive way to answer your question would be to do the experiment. You do not have to have a ph meter. A small strip of litmus paper would do. If you ask a high school chemistry teacher they will be glad to give you a six inch strip. Of course that is not really easy, you have to find a chemistry teacher. It is easier to just speculate (or ask the specific question here in hopes of getting a real answer.
I think that there will not be any significant difference. Flat coke has lost carbon dioxide which is not acidic. The carbolic acid will be left behind as will the citric acid and phosphoric acid. You can get additional information on this subject by asking search engines acid coke” or some variant. One wesult will be

•      Urban Legends Reference Pages: Coca-Cola Acids
The citric acid in Coke removes stains from vitreous china. 5. To remove rust spots from chrome car bumpers: Rub the bumper with a crumpled-up piece of Reynolds Wrap aluminum foil dipped in Coca-Cola.
o      www.snopes.com/cokelore/acid.asp 
--
By the way the strength of the acid in coke, flat or otherwise, is much less than the hydrocloric acid in our stomachs.

Author

Commented:
I know that gastric acid is way more acid than coke, however drinking even more acid can still burn.
I also know about all these hoaxes about coke destroying teeth, washing toilets, dissolving steaks, etc.

you mention Carbolic acid, where did you find out there was any in coke ? Anyway that's the whole question, what is the main source of acidity. I know it's not citric acid as it does not contain that much.

By rereading your post I guess it was a typo and you meant carbonic. If that's the case you're wrong, carboNic acid is just carbonic dioxide in aqueous solution. If you evaporate that acid by shaking it turns back into CO2, thus probably raising the pH. but of how much is what I want to find out.

I have a friend who's got a pH-Meter for his pool I believe. I'll check that with him unless someone does it before and replies.

Thanks
Commented:
Carbonic acid is a bit interesting... the H2CO3 molecule is said to be "hypothetic", because it hasn't been isolated. Some dissolution takes place, though, when CO2 is dissolved in water; you'll have H3O+ and HCO3-, but in very small concentrations. Removing CO2 will not alter pH very much IMHO; citric acid and, obviously, phosphoric acid are much stronger acids (though still "weak" acids) than carbonic acid. The fact that several weak acids are involved will also make it probable that the solution has good buffering capability. Removing one acid, as it were, will not alter pH much, as other acids will dissolve more and keep the pH fairly constant.
/RID

Author

Commented:
Thanks rid,

That's exactly the kind of answer I expected. I found a pH-meter from a friend and just did the test. According to your thoughts, the difference is barely noticeable. Coke pH=2.52, Flat Coke pH=2.57.

I didn't notice that all acids present were actually weak and therefore buffering and keep the pH low, good thought.

That's enough for me, thanks all

Do more with

Expert Office
Submit tech questions to Ask the Experts™ at any time to receive solutions, advice, and new ideas from leading industry professionals.

Start 7-Day Free Trial