Page 1 of 1

12.49

Posted: Tue Dec 05, 2017 2:58 pm
by Abigail Urbina 1K
Question 12.49 on the homework says:
Which is the stronger base, the hypobromite ion, BrO- , or morphine, C17H19O3N? Justify your answer.

The answer to the question is that the stronger base is the hypobromite ion.

I understand that for oxoacids, the more oxygen atoms there are in a compound, the stronger it is as an acid. Would it be correct to conclude that the hypobromite ion is a stronger base because there are less oxygen atoms? Or is there a better way to approach this question conceptually to determine which of the two is a stronger base? The solution manual provides the values of the pKb of both, but how exactly are we expected to figure that out if no numbers are given in the question? Is that a value given to us/a value we must memorize?

Is there a way to answer the question just by looking at the formula?

Re: 12.49

Posted: Tue Dec 05, 2017 3:08 pm
by Emily Glaser 1F
From my understanding, you have to look at this problem from a different perspective. I believe thee rule about increasing oxygen atoms has to do with acids. This problem deals with bases, so I inferred that it would be the opposite. Without the numerical values of pKb, I was able to determine the stronger base because BrO- literally has a negative charge, meaning it is a Bronsted Base (proton acceptor) and would readily take that H+ more than the other compound.

Re: 12.49

Posted: Wed Dec 06, 2017 7:25 am
by Nha Dang 2I
Not sure if we'll have the pKb/pKa provided but based on the tables in the text, the pKb of the hypobromite ion is 5.31 and the pKb for C17H19O3N is 5.79. Since the pKb of hypobromite is smaller, it's the stronger base.