Question

1. AgCl (s) <-> Ag+ (aq) + Cl- (aq) Ksp = 1.8 x 10^-10

Ag+ (aq) + 2S2O3^2- (aq) <-> Ag(S2O3)2^3- Kf = 2.9 x 10^13

Consider the two above equilibria. If sodium thiosulfate solution were added to a solution containing the silver chloride equilirbium (first equilibrium above) the silver chloride equilibrium would shift toward the reactants (TRUE OR FALSE)

2. AgCl (s) <-> Ag+ (aq) + Cl- (aq) Ksp = 1.8 x 10^-10

Ag+ (aq) + 2S2O3^2- (aq) <-> Ag(S2O3)2^3- Kf = 2.9 x 10^13

Let's work quantitatively on the previous question. What would the thiosulfate (S2O3^2-) concentration need to be in order to increase the solubility of AgCl to 0.5 M? (Please answer with 1 sig fig, and regular notation...NOT SCIENTIFIC NOTATION!)

3. According to the first law of thermodynamics, energy cannot be created or destroyed (TRUE OR FALSE)

4. According to the second law of thermodynamics, for any process, the entropy of the universe must decrease. (TRUE OR FALSE)

5. If a system has 5 x 10^20 possible microstates, then what is the entropy of the system?

a. 6.58 x 10^-22 J/K

b. 6.9 x 10^-3 J/K

c. 47.66 J/K

d. 5 x 10^20 J/K

Answer 1

1.) The statement is true.As the concentration of Ag⁺ increases, due to the common ion effect to regain the equilibrium state, the reaction has to move in the backward direction i.e formation of reactants is favoured.

3) True. As per the 1st law of thermodynamics, energy can be transformed from one form to another but can neither be created nor can be destroyed.

4) False. The entropy of the universe either increases or remains the same.

5) As per the boltzman's equation

entropy,S = k*lnW ; where k = Boltzman constant = 1.38*10^-23 J/K ; W = number of microstates

or, S = (1.38*10^-23)*(5*10²⁰) = 6.9*10^-3 J/K