Which of the following can be a Bronsted-Lowery Acid?
a) H2O
b) AlCl3
c) CH4
d) NaOH
e) H2

Question

Which of the following can be a Bronsted-Lowery Acid?
a) H2O
b) AlCl3
c) CH4
d) NaOH
e) H2

adamconner · Answer

I know bronsted lowery acid is the H+ donor
so would it be A) H20 ?

4n1m0s1ty · Answer

I think you're right. H2O kind of falls in the middle between a acid/base. But its probably the best answer on the list.

anonymous · Answer

You're right that a Bronsted acid is a compound that can donate a proton. Of those compounds, only water is able to do so. Indeed, it can be both a donour and an acceptor of protons. 

AlCl3 is a Lewis acid but it can't generate protons, so it's not a Bronsted acid.
CH4 is highly unreactive, so it's not an option, either.
NaOH is a base, it dissociates to Na+ and OH-. In the Bronsted-Lowry classification, it is an acceptor of protons (H+  +  OH-   ->  H2O)

Hydrogen gas is barely soluble in water, we could say that it practically isn't. So, it can't give out H+, either.