Which equation would describe the following equilibrium constant?
Kc = [Bi3+]2[S2-]3
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Bi2S3 (s) <-> 2Bi3+ (aq) + 3S2- (aq)
Bi2S3 (s) + 6HCl (aq) <-> 2BiCl3 (aq) + 3H2S (aq)
BiS (s) <-> Bi3+ (aq) + S2- (aq)
Bi2S3 (s) <-> 3Bi2+ (aq) + 2S- (aq)
Bi2S3 (s) <-> 2Bi3+ (aq) + 3S2- (aq)
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The equation that describes the given equilibrium constant, Kc = [Bi3+]2[S2-]3, is the one that corresponds to the equilibrium expression with the same stoichiometric coefficients. In this case, it is the equation:
Bi2S3 (s) <-> 2Bi3+ (aq) + 3S2- (aq)
To determine the equation that matches the given equilibrium constant, we look for a balanced equation in which the concentrations of Bi3+ and S2- in the equilibrium expression are raised to the powers indicated in the equilibrium constant expression.
By comparing the powers of the concentration terms, we can see that the equation:
Bi2S3 (s) <-> 2Bi3+ (aq) + 3S2- (aq)
matches the equilibrium constant expression:
Kc = [Bi3+]2[S2-]3
Therefore, the equation that describes the given equilibrium constant is:
Bi2S3 (s) <-> 2Bi3+ (aq) + 3S2- (aq)