Question

Which of the following solutions is most likely to have the lowest pH? Explain
a. 0.010 M propanol
b. 0.010 M propanoic acid
c. 0.010 M propyl amine
d. 0.10 phenol
e. 0.010 propanethiol

Answer 1

look at the pka of each chemical, the lower the pka the more likely a hydrogen will dissociate

Answer 2

It is good to know the ball park pka of certain compounds, for example amines

Answer 3

So, a lower pka indicates a stronger acid?

Answer 4

yes

Answer 5

Another good way to judge the strength of an acid is to look at the electron withdrawing groups on it, the more electron withdrawing groups on a molecule the stronger the acid

Answer 6

well in organic chemistry

Answer 7

Ok, thanks. Would it be correct to rule out the amine w/o looking at pka value because amines are basic?

Answer 8

yes

Answer 9

it would be correct

Answer 10

did you figure it out?

Answer 11

My book doesn't have a lot of these in the pKa table so I'm just trying to look them up. I also assume it can't be the alcohol becaues of the basic OH group

Answer 12

just look on Wikipedia, and OH groups can act as an acid if resonance stabilized or attached to a benzene ring

Answer 13

but yeah they can also act as a base

Answer 14

really the answer is pretty obvious :)

Answer 15

propanoic acid?

Answer 16

Yeah, I got it for sure now

Answer 17

yeah that is correct

Answer 18

notice, the leaving of an oxygen is resonance stabilized,, also oxygen is pretty electronegative, thus electron density is pulled away from the hydrogen allowing it to leave easier