Question

Using the Brønsted-Lowry concept of acids and bases, which is the Brønsted-Lowry acid and base in the following reaction? HS−(aq)+H2O(l)→H2S(aq)+OH−(aq)

Answer 1

The HS⁻ is the Brønsted-Lowry base; the H₂O is the Brønsted-Lowry acid.

You can learn how to identify Brønsted-Lowry acids an bases at

http://socratic.org/questions/what-are-bronsted-lowry-acids-and-bases

In your equation

HS⁻ + H₂O → H₂S + OH⁻

The HS⁻ has become H₂S. It has one more H atom. It has accepted a proton (H⁺), so it is a Brønsted-Lowry base.

The H₂O has become OH⁻. It has one less H atom. It has donated a proton (H⁺), so it is a Brønsted-Lowry acid.

Hope this helps.