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Topic: How do I determine the analyte and titrant in a titrant curve?  (Read 1370 times)

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Offline LackOfNames34

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Hello! I'm working on a chemistry assignment and have struggled with a question about describing a given titration curve graph (link to picture below, I also attempted to attach the image).

https://drive.google.com/file/d/1ymNKFzBV8hhGjrbjRJeFqi8ZIhXI3cEB/view?usp=sharing

The question I'm having issues with is:

 "Identify if the analyte and titrants are strong or weak acids/bases"

 I'm pretty much lost on where to start. But if I had to guess, I would say it's a weak acid strong base because the starting PH is higher than 0. But I'm by no means confident in this answer. Did I approach this question correctly? And if not, what should I do?

Offline Borek

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Re: How do I determine the analyte and titrant in a titrant curve?
« Reply #1 on: May 02, 2021, 05:34:47 PM »
I would say it's a weak acid strong base because the starting PH is higher than 0.

It all depends on the concentration: what is pH of 0.01 M HCl? Is HCl a strong acid?

I am not sure there is enough information to answer the question. Separation of endpoints tells a lot about second and third dissociation constants, but not so much about the first.
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Offline LackOfNames34

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Re: How do I determine the analyte and titrant in a titrant curve?
« Reply #2 on: May 02, 2021, 06:23:34 PM »
Would knowing the pKa1 and pKa2 values help? Because I have those two values as well.

Offline Borek

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Re: How do I determine the analyte and titrant in a titrant curve?
« Reply #3 on: May 03, 2021, 02:43:12 AM »
If you refer to the values read at half-points - beware, as pKa1 is incorrect (think again about 0.01 M HCl  titration, at half point its pH is about 2.5, does it mean pKa of HCl is 2.5?).
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