Which of the following is the correct expression for the rate of the following reaction? Note: not all species are gaseous.
CuO(s) + H2S (g) <--> Cu(s) + H2O (g)
a) [H2O] / [H2S]
b) None of these are correct
c) [Cu] x [H2O] / ([CuO] x [H2S])
d) [CuO] x [H2S] / ([Cu] x [H2O])
Equilibrium constants are written to include only aqueous and gaseous species. Solids and pure liquids are considered to have activities of 1, and are omitted. So, for the reaction
CuO(s)+H2S(g)⇌CuS(s)+H2O(g),
which should be inspected and compared to the one given in the question (how did sulfur enter and not get produced again?), the solid copper(II) oxide and solid copper(II) sulfide (not elemental copper) are omitted, and we only write:
Keq=[H2O]/[H2S]
I notice that the question asks about the RATE equation but all of the expressions in the multiple guess answers are written as possible equilibrium constants. I would venture that the correct answer is B; i.e., none of these since none of them are rate equations.
To determine the correct expression for the rate of the given reaction, we need to consider the stoichiometry of the reaction and the rate law expression.
The balanced equation for the reaction is:
CuO(s) + H2S(g) <--> Cu(s) + H2O(g)
From the balanced equation, we can see that the coefficients for the reactants are 1 and 1, respectively. This suggests that the rate of the reaction may directly depend on the concentrations of CuO and H2S.
Now, let's analyze the given options:
a) [H2O] / [H2S]: This expression does not take into account the concentrations of CuO and Cu, which are also part of the reaction. Therefore, it is not a correct expression for the rate of the reaction.
b) None of these are correct: This option does not provide any expression, so we cannot consider it as the correct answer.
c) [Cu] x [H2O] / ([CuO] x [H2S]): This expression incorporates the concentrations of all the reactants in the numerator and denominators. It considers the concentrations of Cu, H2O, CuO, and H2S, which are all part of the reaction. Therefore, it is a possible correct expression for the rate of the reaction.
d) [CuO] x [H2S] / ([Cu] x [H2O]): Similar to option c, this expression includes the concentrations of all the reactants. However, the order of the concentrations in the numerator and denominator is different from option c. The rate law expression is typically determined experimentally, so it is possible that either option c or d could be correct, depending on the specific experimental results.
In summary, the correct expression for the rate of the given reaction is either option c) [Cu] x [H2O] / ([CuO] x [H2S]) or option d) [CuO] x [H2S] / ([Cu] x [H2O]). The specific rate law expression would need to be determined experimentally.