[Diamonds]

How is the titration represented by this curve diprotic? http://imgur.com/dlRFrGN

I can see how the hump kind of says it, but wouldn't it have to be like a vertical line?

Thank you in advance.

[Borek]

I can see how the hump kind of says it, but wouldn't it have to be like a vertical line?

No. Whether there is more than one well visible inflection point depends on the relative strengths of the protons.

Download my pH calculator (see the signature, there is a 30 days free trial) and play with titration curves - sometimes they do have two inflection points, sometimes they have only one, sometimes they have one and some kind of hump, just like the curve you posted.