Question

Table 1	25c
HCl Concentration (M)	Cell Potential (mV)	ln(M)
1	389.3	0
0.1	340.7	-2.302585093
0.01	292	-4.605170186
0.001	249.1	-6.907755279
0.0001	215.7	-9.210340372

A) Obtain the value of the ideal gas constant (R) in units of joules per mole-kelvin and the value of the Faraday constant (F) in units of coulomb per mole. Calculate the ratio of these constants: R/F. Use the fact that one volt is one joule per coulomb to calculate the units of R/F.

B) Multiply the ratio R/F by the absolute temperatures in kelvin and compare the value of RT/F with the average values of the slope of the line obtained at each temperature for which data were collected.

C) Compare the average value of the slope at the three temperatures with the value of RT/F at each temperature. Are they the same in each case?

Table 2	25c
Cu2+ Concentration (M)	Cell Potential (mV)	ln(M)
0.1	294.4	-2.302585093
0.05	262.7	-2.995732274
0.025	253.4	-3.688879454
0.01	231.7	-4.605170186
0.005	205.5	-5.298317367

Compare the average value of the slope of the straight line obtained in this part of the experiment with the value of RT/F at the temperature at which measurements were taken. Are they the same? What relationship between the H+ ion studied in Part I and the Cu2+ studied in Part II can be used to explain the difference between the behavior of these ions?

Answer 1

A)     101325 N/m2 0.0224 m3 R = ----------------------
       1 mol 273 K

   = 8.314 J / (mol·K)

The charge that each electron carries is 1.60 x 10^-19 coulombs. 1 mole of electrons contains the Avogadro constant, L, electrons - that is 6.02 x 10²³ electrons

That means the 1 mole of electrons must carry

6.02 x 10²³ x 1.60 x 10^-19 coulombs

= 96320 coulombs, Coulomb= joule/volt

This value is known as the Faraday constant

put for practical situations we take it as 96500.

ratio of R/F = 8.314/96500 = 8.61 * 10^-5 volt/mol K

B)

2.303 * RT/F = 0.0256 * 2.303 = 0.0591(AT 25 degrees) other temperatures are not mentioned in that question but ill give u the idea of doing it

you can compare now with the other temperatures