pH and acidity exercise: Vinegar vs. Coca Cola

Reginald SmithUncategorized2 Comments

Based on our last post outlining the differences between pH and acidity as measures of acid strength, a short exercise will help emphasize the differences. Here we will compare two deceptively similar acids: 5% store bought white vinegar and Coca-Cola classic.

White Vinegar


As stated before, 5% white vinegar has an acidity of 5% which means 5 grams of acetic acid (CH3COOH)

per 100 mL of vinegar. In addition, the pH usually is in the 2.5 – 2.7 range.


Coca-Cola Classic

Now, is Coca-Cola Classic as acidic as white vinegar? A first (but incorrect) assessment would look at the fact that the average pH of Coca-Cola Classic is about 2.53. This puts it at the lower range of white vinegar. However, as discussed before, the grams of acid per liquid is what matters since the quantity of acid dictates how much it can act (and dissolve) other compounds.

The active acid in Coca-Cola Classic is phosphoric acid (H3PO4). The average amount per can of coke works out to 17mg per 100 mL of Coca-Cola. This gives an acidity of only 0.017%. Granted, since phosphoric acid has three hydrogens instead of one like acetic acid there are some chemical considerations but they are not as relevant at this low concentration.


2 Comments on “pH and acidity exercise: Vinegar vs. Coca Cola”

    1. The ultimate source for that number seems to be:

      Scherz H, Senser F. Food composition and nutrition tables. Medpharm GmbH Scientific Publishers; Zurich: 1994

      But I don’t have access to that book and got the number from this paper.
      Aghili, H. A., Hoseini, S. M., & Yassaei, S. (2014). Effects of carbonated soft drink consumption on orthodontic tooth movements in rats. Journal of dentistry (Tehran, Iran), 11(2), 123.

      If you have another, better number, let me know. Also I feel this probably varies by country and production location.

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