Two part problem, please show work If the voltage of the galvanic cell Pt, H_2 (

Question

Two part problem, please show work

If the voltage of the galvanic cell Pt, H_2 (0.750 atm) | solution of unknown pH | Hg_2Cl_2(s), KCl(s) Hg is 0.0.427 volt, calculate the pH of the unknown solution. Data: To determine the value of the equilibrium constant (K_b) for the proton-transfer reaction between tricthylaminc, (H_3CCH_2)_3 N, and water, H_2O (H_3CCH_2)_3N + H_2O (H_3CCH_2)_3 NH^+ OH^- the following galvanic (voltaic) cell was constructed: Pt. H_2(g) (0.500 atm) | (H_3 CCH_2)_3 N (0.0700 M). (H_3 CCH_2)_3 NH^+ (0.100 M) ||Hg_2 Cl_2(s). KCl(s) | Hg If the voltage of the cell is 0.861 volt, what is the value of K_b? For pertinent data, sec Problem 3.

Explanation / Answer

3. E = Ecal - EH = 0.242 - 0.059log[H+] = 0.242 + 0.059pH

therefore pH = (E - 0.242)/ 0.059 = (0.427 -0.242)/ 0.059 = 3.14

4. pH = (E - 0.242)/ 0.059 = (0.861 -0.242)/ 0.059 = 10.49

hence

pOH = 14 - pH = 14 - 10.49 = 3.51

so [OH-] = 10-3.51 = 3.1 x 10-4

Now Kb = [OH][BH+]/ [B] where B is the amine

= 3.1 x 10-4 x 0.1/ 0.07 = 4.41 x 10-4

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