What is the [
] at equilibrium,given CuS,
?

Question

What is the [ 
] at equilibrium,given CuS, 
?

Quizplus · Accepted Answer

The equilibrium equation between CuS and Cu2+ is: CuS(s) ⇌ Cu2+(aq) + S2-(aq)
The solubility product constant, Ksp = [Cu2+][S2-]/[CuS]
At equilibrium, the amount of CuS does not change, therefore, [CuS] can be considered constant. Since [Cu2+] and [S2-] have equal stoichiometric coefficients, they will have the same concentration at equilibrium, which can be represented as x. Therefore, [Cu2+] = [S2-] = x.
Substituting these values in the expression for Ksp, we get:

Ksp = x^2/[CuS] = x^2

Solving for x using the value of Ksp, we get:

x = sqrt(Ksp) = sqrt(5.5 x 10^-36) = 2.35 x 10^-18 M

Since [Cu2+] = [S2-] = x, the equilibrium concentration of Cu2+ is 2.35 x 10^-18 M, which is closest to choice C (5.2 x 10^-18 M).

What Is the [