Question

which set of values tells us if the reaction is at equilibrium? a = 5.8x10^(-5)m co_3^2- = 5.8x10^(-5)m b k = 47m/s k_sp = 3.34x10^(-7) c rate of precipitation = 2.1x10^(-8) m/s rate of dissolution = 2.1x10^(-8) m/s

Explanation:

Step1: Recall equilibrium condition

At equilibrium, the rate of the forward reaction equals the rate of the reverse reaction. In the case of a precipitation - dissolution reaction, when the rate of precipitation is equal to the rate of dissolution, the system is at equilibrium.

Step2: Analyze each option

Option A just gives concentrations of species, which alone don't determine equilibrium. Option B gives a rate constant ($k$) and a solubility - product constant ($K_{sp}$), which are not sufficient to determine if the reaction is at equilibrium. Option C shows that the rate of precipitation is equal to the rate of dissolution, which is the condition for equilibrium in a precipitation - dissolution system.

Answer:

C. Rate of precipitation = 2.1x10⁻⁸ M/s, Rate of dissolution = 2.1x10⁻⁸ M/s