# Does changing the concentration of reactants alter the equilibrium constant

$$\ce{S(s) + O2(g) -> SO2(g)}$$

The reaction of sulfur with oxygen is written in equation form above. This equation can be interpreted in all of the following ways except
(A) either $$\ce{S(s)}$$ or $$\ce{O2(g)}$$ will be completely used up
(B) $$Q$$ must be close to $$1.0$$ since there is one mole of gas on each side of the equation
(C) this reaction goes to completion
(D) adding $$\ce{O2}$$ will change the equilibrium constant

I do not know how to extrapolate $$Q$$ from just an equation with no other data. However, I also learned that the equilibrium constant is, well, constant, and adding O$$_2$$ should change the equilibrium concentrations, not the equilibrium constant.

The correct answer is (B). How would (D) be a valid interpretation?

• I'd say it wouldn't. Your interpretation is correct, and the test is inaccurate. – Ivan Neretin May 1 '19 at 6:49