Hi, guys.
I'm now self-studying A-level Chemistry and i really need your help to past the exam.
It is one question from Equilibria Chapter.
http://www.flickr.com/photos/mabuthaodang/8406625517/in/photostream
There are 4 choice :
A CH3CO2H and NH3
B.CH3CO2J and KOH
C.HCl an KOH
D.HCl and NH3
E.H2SO4 and KOH
How can we know that the acid is the monobasic and the base is the monobasic?? Can someone explain for me. Thank you :)
In future, each time you ask a new qn, pls start a new thread for each new qn, and do include the topic asked in the thread (notice that I've edited ur thread title to include the word Equilibria). A generic "A level Chem qn" thread title isn't informative.
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#1 - The initial pH is too low to be a weak acid, hence the acid is a strong one.
#2 - There is only 1 vertical region, and hence only 1 equivalence point. And since the molarities and volumes of both acid and base required to reach equivalence point are the same, therefore both acid and base must be monoprotic.
#3 - The pH at equivalence point is approx 4, which means the salt is acidic, which means it was generated in a Bronsted-Lowry acid-base proton transfer reaction between a strong acid and a weak base.
Hence the MCQ answer is Delta.
Thank you for editing my thread title and answering my question. Before,when i joined other forum, they don't want me to start a new thread if there are some similar content. Anw,i will fix it next time.
I got what you mean but there the similar excercise with the similar curve. It has 1 equivalence point too but the answer ...
http://www.flickr.com/photos/mabuthaodang/8406625669/
The answer from the book is E but i think it is A
Originally posted by Theplayfulgirl brainy:Thank you for editing my thread title and answering my question. Before,when i joined other forum, they don't want me to start a new thread if there are some similar content. Anw,i will fix it next time.
I got what you mean but there the similar excercise with the similar curve. It has 1 equivalence point too but the answer ...
http://www.flickr.com/photos/mabuthaodang/8406625669/
The answer from the book is E but i think it is A
Yes, you're correct. The base must have been diprotic, based on the volumes and molarities of both acid and base used.
oh really... It is so nice
Thank you
Hmm but i just wonder how they sketch the graph of E
Originally posted by Theplayfulgirl brainy:Hmm but i just wonder how they sketch the graph of E
Similar to that of A, but the x-axis values would be different : if both acid and base are monoprotic, and both have equal molarities, it follows that both must require the same volume to reach equivalence.