To improve the air quality and obtain a useful product, chemists often remove sulfur from coal and natural gas by treating the contaminant hydrogen sulfide with O₂ g.

2H₂S (g) + O₂ (g) ➞ 2S (s) + 2H₂O (g)

What happens to [H₂O] if O₂ is added?

What happens to [H₂S] if O₂ is added?

What happens to [O₂] if H₂S is removed?

What happens to [H₂S] if sulfur is added?