The given graph is a titration curve obtained for an acid base titration. How many protons are released from the acid used in this titration ? (Hint:asking whether monoprotic, diprotic...etc)

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BlackTom AI · Accepted Answer

To unpack what this titration curve is telling us, start by looking at the shape of the curve: a titration curve with two distinct vertical jumps in pH typically indicates two successive equivalence points, each corresponding to the neutralization of one proton from a polyprotic acid.

First, consider the initial region: the pH starts near acidic values (around 2–3), which is consistent with an acid in solution before any base is added. As NaOH is added, the pH rises gradually, then shows a sharp, steep transition around the first equivalence region (roughly near 10 mL). This first steep ascent corresponds to the neutralization of the first acidic proton.

Next, after the first equivalence point, the curve continues with another gradual rise and then a second, well-defined vertical jump around a higher volume (near ~20 mL). This second step signifies the neutralization of the second proton from the same acid species. The presence of two clear equivalence points is the hallmark of a diprotic (or polyprotic) acid, not a monoprotic one, because a monoprotic acid would typically show only a single equivalence point in its titration curve with a single sharp rise.

Thus, the acid being titrated can release two protons in total during complete titration with base. The fact that there are two distinct regions of rapid pH change (two equivalence points) directly supports a two-proton donation process, i.e., a diprotic acid.

Why the other interpretations would be incorrect:
- If it were monoprotic, you would expect only one sharp vertical region corresponding to one equivalence point; the curve would level off after that point rather than showing a second steep rise later on.
- If you assumed a triprotic or higher-order acid, you would anticipate three or more distinct equivalence points; here only two are observed, not three.
- Merely looking at the initial or final pH values does not determine the number of protons released; it is the number and positions of the equivalence points that reveal the proton count handled during titration.

In summary, the two clear equivalence points observed in the titration curve indicate that the acid can donate two protons in total, i.e., it is diprotic.

The given graph is a titration curve obtained for an acid base titration. How many protons are released from the acid used in this titration ? (Hint:asking whether monoprotic, diprotic...etc)

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