Is H2S a lewis acid or a lewis base?

Hydrogen sulfide (H₂S) is generally considered to be a Lewis base rather than a Lewis acid. The reasoning behind this classification is based on the definition of Lewis acids and bases:

A Lewis acid is a substance that can accept an electron pair.
A Lewis base is a substance that can donate an electron pair.
In the case of H₂S, the sulfur atom has lone pairs of electrons that can be donated to other species. This makes H₂S a Lewis base. It can act as a donor of electron pairs in chemical reactions, forming bonds with species that can accept those electrons (Lewis acids).

Therefore, H₂S functions primarily as a Lewis base due to the presence of lone pairs on the sulfur atom that are available for donation.