General Chemistry II - Chem 1412, HCC
18 November 2022
Post Lab 9 [Extra pt X]
Electrochemical Cells and Thermodynamics.
INTRODUCTION [one paragraph]
[Describe the Nest equationt]
The Nernst equation provides a relation between the cell potential of an electrochemical cell, the
standard cell potential, temperature, and the reaction quotient. Even under non-standard conditions,
the cell potentials of electrochemical cells can be determined with the help of the Nernst equation.
The Nernst equation is often used to calculate the cell potential of an electrochemical cell at any
given temperature, pressure, and reactant concentration. The equation was introduced by a German
chemist named Walther Hermann Nernst. Ecell = E0 – [RT/nF] ln Q
Where,
Ecell = cell potential of the cell
E0 = cell potential under standard conditions
R = universal gas constant
T = temperature
n = number of electrons transferred in the redox reaction
F = Faraday constant
Q = reaction quotient
The calculation of single electrode reduction potential (Ered) from the standard single electrode
reduction potential (E°red) for an atom/ion is given by the Nernst equation.
EXPERIMENTAL (max 2 paragraphs)
[Concise Description of the experimental procedure]
First, we make a complete cell by placing 30 mL of 1M Zn(NO3)2 and 30 mL of 1M Cu(NO3)2 in
separate large test tubes. We then put in a U-tube which had 100 mL of 0.1M KNO3 then plug
cottons plugs to the ends of the U-tube. We then place the U-tube in the test tubes as a salt bridge.
Next, we insert a zinc strip into the Zn(NO3)2 solution and the copper strip into the Cu(NO3)2
solution. We then used a voltmeter to measure the voltage of the cells on the report sheet. This cell
was Zn | Zn2+ (1M) || Cu2+ (1M) | Cu.
, We then repeated the steps with two different cells: Sn | Sn2+ (1M) || Cu2+ (1M) | Cu (a tin strip and a
copper strip) and Pb | Pb2+ (1M) || Cu2+ (1M) | Cu (a lead strip and a copper strip). From the
measured voltage, we then can calculate the half-cell potentials for these cells. We used E0 = 0.34 V
for the Cu2+ | Cu couple.
Fig 1: [picture of microlab system ]
Graph 1: [show the graph of the potential [V] in function of the concentration M ]
Zn | Zn2+ (1M) || Cu2+ (1M) | Cu cell