When you say "titration curve" I'm going to assume this: you have a beaker with some acid solution in it and a pH probe stuck into the solution. You titrate from a burette some base solution of known concentration. As you add base, you record periodically what volume of base has been added and what the pH meter says. That way you get a graph of pH versus volume. It starts from low pH at zero added base volume and the pH changes very little for a while, then rises much more rapidly (i.e., over a short span of base volume increase), then nearly levels out again. For a diprotic acid there should be two rises in the total curve.
Now, the term "strong acid" usually means that the acid molecule in water dissociates very easily so that the solution has a very high concentration of H+ ions. That also means, usually, that a very high proportion of the acid molecules are dissociated into ions. So the first clue is the pH at which the titration curve rises suddely - that's the equivalence point for that proton. If that happens at a very low pH then you had a very high H+ ion concentration before adding the base, and that could be considered a strong acid. The other clue is the slope of the rise of pH versus volume. If the rise is very fast, it indicates that the molecules were highly dissociated before any base was added, and this also indicates a stronger acid. But if the rise is more gradual over a wider range of added base volume, then the dissociation was incomplete and it took the addition of neutralizing base (OH-) ions to consume the H+ and force dissociation of more acid molecules. That would be considered a weak acid.
I once tried to analyze the acid content of a wine I was starting to ferment to be sure I had added the right amount of three fruit acids. But they were all weak acids and the titration curve had three very broad pH rises overlapping, so the curve looked more like a gentle slope up with almost no recognizable "knee" in it. Could not get the answer I wanted that way.
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