Page 31 - Lab Manual & Project class 12


–1
–1
Here R is the gas constant (8.314 JK mol ), F is Faraday
n+
–1
constant (96487C mol ), T is the temperature in Kelvin and [M ]
n+
is the concentration of the species, M .
In the following experiment the variation in the cell potential
2+ 2+
of Zn/Zn ||Cu /C u cell with concentration of electrolytes will
be studied.



Maxbrain Chemistry


2+
To study the variation in cell potential of the cell Zn/Zn ||Cu /Cu
2+
with change in concentration of electrolytes (CuSO /ZnSO ) at room
4 4
temperature.


The cell under investigation in this experiment is represented as
follows:
2+
2+
Zn(s)/Zn (aq., 1.0M) || Cu (aq., x M)/Cu(s)
2+
Here x M denotes varying concentrations of Cu (aq) ions. In
other words, to study the variation in cell potential with
concentration, the concentration of Cu (aq.) is varied while that
2+
2+
of Zn (aq) is kept constant. The measured cell potential enables
us to calculate the electrode potential of Cu /Cu electrode for
2+
each concentration of copper (II) ions. This variation is theoretically
depicted according to the equation:
2+
E = E  + 0.059 log[Cu ] (1)
Cu 2+ /Cu Cu 2+ /Cu 2
2+
The variation in the electrode potential of Cu /Cu electrode
consequently brings variation in the cell potential according to
the relation:

E = E − E (2)
cell Cu 2+ /Cu Zn 2+ /Zn

Equation (2) clearly suggests that even if E 2+ is kept
Zn /Zn
constant, the variation in E would bring corresponding
Cu 2+ /Cu
variation in E (cell potential). Similarly, keeping the concentration
cell
of Cu ions constant, one can study the variations in the cell
2+
2+
potential with the variation in concentration of Zn ions.



24-04-2018