Question

to improve air quality and obtain a useful product, chemists often remove sulfur from coal and natural gas by treating the contaminant hydrogen sulfide with o₂.
2h₂s(g) + o₂(g) ⇌ 2s(s) + 2h₂o(g)
which of the following statements is true?
○ if h₂o is removed, this will cause q < k
○ when h₂s is removed, this will cause q < k
○ when o₂ is added, this will cause q > k
○ when s is added, this will cause q > k.

Explanation:

Step1: Write the expression for \(Q\)

For the reaction \(2H_{2}S(g)+O_{2}(g)
ightleftharpoons 2S(s)+2H_{2}O(g)\), the reaction - quotient \(Q=\frac{[H_{2}O]^{2}}{[H_{2}S]^{2}[O_{2}]}\) (since \(S\) is a solid and its concentration is taken as \(1\) in the expression of \(Q\) and \(K\)).

Step2: Analyze the effect of removing \(H_{2}O\)

If \(H_{2}O\) is removed, the numerator of \(Q\) decreases. So, \(Q < K\) (because \(K\) is a constant at a given temperature).

Step3: Analyze the effect of removing \(H_{2}S\)

If \(H_{2}S\) is removed, the denominator of \(Q\) decreases. So, \(Q>K\) (not \(Q < K\)).

Step4: Analyze the effect of adding \(O_{2}\)

If \(O_{2}\) is added, the denominator of \(Q\) increases. So, \(Q < K\) (not \(Q>K\)).

Step5: Analyze the effect of adding \(S\)

Since \(S\) is a solid, adding \(S\) does not change the value of \(Q\) (because the concentration of a solid is constant and not included in the \(Q\) - expression).

Answer:

If \(H_{2}O\) is removed, this will cause \(Q < K\)