I am having trouble with understanding this question:

Calculate the pH of a solution containing only hydrogen sulphide and water where:

[H₂S] = 10^-2 and [S^2-] = 10^-7

In this situation, is water actually part of the equation or is it represented by H₂S (aq), with H⁺ and HS^- as the products? I can only find conflicting solutions to this problem that are solved by means outside of what is in my course material.

If someone would be able to provide an explanation alongside a solution to this problem that would be greatly appreciated. Thanks!