Electrochemistry Experiment. Objective: To investigate the effect of change in lead(II) ion concentration on the potential of the Pb2+(aq) ∣Pb(s) electrode

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Tsuen Wan Public Ho Chuen Yiu Memorial College

Form 6 Chemistry Practical

Experiment 15: Electrochemistry

Date of experiment: 8/4/2011

Introduction:

Redox reactions are reactions where the oxidation states of the atoms change. The atoms are either oxidized or reduced, depending if they lose or gain electrons.

Electrochemical cells are devices that cause a current from redox reactions. It is set up so that electrons lost from one of the reagents can travel to another reagent. This creates a voltage, which is also known as the electric potential difference. This voltage can be read if a high-resistance voltmeter or multimeter is connected to the circuit

Salt bridge is used to allow migration of ions between two electric cells to maintain neutrality of solutions. It is usually made up of a filter paper moistened with an inert solution or an inert solution/gelatine salt bridge to prevent oxidation of certain ions.

This experiment is divided into 2 parts: part A and part B.

Part A

Objective: To investigate the effect of change in lead(II) ion concentration on the potential of the Pb2+(aq) ∣Pb(s) electrode

Introduction:

This experiment investigates the e.m.f. of the cell:

    Cu(s) ∣Cu2+(aq) ∣Pb2+(aq)∣Pb(s)

Keeping the ion concentration in the copper electrode system constant(1M) and varying the ion concentration in the lead electrode system, the effect of change in lead(II) ion concentration on the potential of electrode as well as the Kc of the above reaction can be found.

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Chemicals:

Copper foil x1, lead foil x1, 1M Cu2+ solution, 0.1M Pb2+ solution, saturated potassium nitrate solution

Apparatus:

250 cm3 beakers, 50cm3 beakers multimeter, distilled water bottle, filter

papers, electrical wires with electrode holders, forceps, 100ml volumetric

flask,10ml pipette x2, dropper

Procedure:

  1. The 0.1M, 0.01M, 0.001M, 0.0001M Pb2+ solutions were prepared from 0.1M Pb2+ solution by dilution(1 portion solution plus 10 portions water).
  2. The copper and lead electrodes were cleaned with a sand paper.
  3. The circuit was connected as the diagram below.
  4. The e.m.f. was recorded when the data shown was stable.
  5. The above steps(2-4) were repeated with ...

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This is a very well written set of two experiments using electrochemical cells. It is set out and written in a clear and easy to understand way. Unfortunately, the graphs are not present, however the results tables are excellent and valid conclusions are made. Overall, this piece of work is 4 stars out of 5.