# Bronsted acids and bases

1. Nov 10, 2006

### Lookielook

Anyone clever with bronsted acids and bases?

I'm pretty new in chemistry, but I'm trying to learn.
Right now I'm suppose to classify some species as either bronsted acids or bases, or even both.

For example

1. Water
2. OH-
3. NH4+
4. HCN
5. HBr
6. NH3

Hope someone can help!
And does this system have "sup" and "sub" functions?

2. Nov 10, 2006

### geoffjb

Do you need help classifying them, or do you just want answers? You won't get the latter. Show some work.

(1) text [ sub ] down [ /sub ] and [ sup ] up [ /sup ].

E.g. v02

(2) [ tex ] text_{down}^{up} [ /tex ]

E.g. $$v_{0}^{2}$$

You can click on the latter to see how someone created it.

3. Nov 10, 2006

### Lookielook

Thanks a lot! Well, not looking for answers, looking for help to understand. I know that bronsted acids donate protons, while bronsted bases accept protons. But I don't understand the part where a compound can be both bronsted acid and bronsted base.

4. Nov 10, 2006

### geoffjb

The word you're looking for is amphoteric, which is a substance that can act as an acid or a base. Clearly, a substance with no H to donate cannot act as a Bronsted-Lowry acid, just as a substance that does not want/need an H will not act as a Bronsted-Lowry base. Amphoteric substances often have one acidic proton with the capacity for two, such as HSO4- or HCO3-, although this is not always the case (i.e. H2O). Amphoteric substances act based on what they're mixed with. In a strong acid, water will act as a BL base; in a strong base, water will act as a BL acid.

http://en.wikipedia.org/wiki/Bronsted-Lowry
http://www.nyu.edu/classes/tuckerman/honors.chem/lectures/lecture_21/node3.html [Broken]
http://en.wikipedia.org/wiki/Acid-base_reaction_theories

Last edited by a moderator: May 2, 2017
5. Nov 14, 2006