Chemistry Forums for Students > Chemistry Olympiad and other competitions

how to interpret this graph?

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Sophia7X:
http://portal.acs.org/portal/PublicWebSite/education/students/highschool/olympiad/pastexams/CNBP_021762

the question I am having problems with is #5.

The answer is supposed to be B but I can only get A. I used the highest point on the graph (probably around 70 mL) but it didn't work.

Borek:
Approximate both left and right parts with a straight lines. Where do they cross?

Sophia7X:

--- Quote from: Borek on April 10, 2012, 06:10:02 PM ---Approximate both left and right parts with a straight lines. Where do they cross?

--- End quote ---

oh, thanks! I didn't think to do that; I just drew a curve through the dots. 75 works.


On the same test, #35... why isn't this graph a diprotic acid?

Dan:

--- Quote ---On the same test, #35... why isn't this graph a diprotic acid?

--- End quote ---

For a diprotic acid, if the first equivalence point is reached after adding x mol of NaOH, how much more NaOH do you need to add to reach the second equivalence point?

Sophia7X:
So it's not diprotic because the second equivalence point would require 2x?

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