(a) Derive a general relation for (∂E/∂P)T,n for electrochemical cells employing reactants in any state of matter.

(b) E, Cohen and K. Piepenbroek (2. Physik Chem. 167A, 365 (1933)) calculated the change in volume for the reaction TICI(s) + CNS-(aq) → TICNS(s) + Cl-(aq) at 30°C from density data and obtained ∆rV=-2.666 ± 0.080 cm3 mol-1. They also measured the emf of the cell TI (Hg) ITICNS(s) IKCNS: KCII TICII TI(Hg) at pressures up to 1500 atm. Their results are given in the following table:

P/atm 1.00 250 500 750 1000 1250 1500

B/mV 8.56 9.27 9.98 10.69 11.39 12.11 12.82

From this information, obtain (∂E/∂p) T n at 30°C and compare to the value obtained from ∆r V.

(c) Fit the data to a polynomial for E against p. How constant is (∂E/∂p) T,n?

(d) From the polynomial, estimate an effective isothermal compressibility for the cell as a whole.