ELECTROCHEMICAL METHOD OF ANALYSIS

ELECTROCHEMICAL METHOD OF ANALYSIS

Electro analytical methods are concerned with the interplay between electrictiy and chemistry, namely the measurements of electrical quantities, such as current, potential, or/and their relationship to chemical parameters.

If electrical parameter : E-Potentionmetry , R-conductometry, I- voltametry,coulometry

MAIN BRANCHES OF ELECTROANALYTICAL TECHNIQUES:-ENN

  1. INTERFACIAL METHODES :- a. STATIC METHODS (I=0)→POTENTIOMETRY (E)

b. Dynamic Methodes (I>0) it is also divided into two types

1. CONSTANT CURRENT→ COULOMETRIC TITRATION {Q=IT}

2. CONTROLLED POTENTIAL  → VOLTAMETRY (I=FE)

AMPEROMETRIC TITRATION

PARAMETERS OF ELECTRICITY :-

  1. CURRENTS (I):- 1 AMPERE IS THE CURRENT WHICH WHEN FLOWS FOR 1 SEC, OR 1 Ampere is about 6.26×1018 e¯ Passing a point in 1 sec.
  2. Quantity :- unit-coulomb SI unit faraday 1 coulomb is the qty of electricity equal to 1 ampere current allowed to flow for 1 sec.  1 faraday= 96,500 coulomb = 1 mole e¯
  3. Electromotive force :- It is the force which causes e¯ to move. 1 volt is the potential req. to force 1 ampere current through a resistance of 1 ohm.
  4. Resistance :- It is an inherent property of metal to retard the flow of electricity. Unit : Ohm. 1 Ohm is the resistance at 0°C of a column of mercury with a uniform cross-section and 106.3cm long weighing 14.4251gmHg.
  5. Conductance:-  Inherent property of the material to allow electricity to pass through. units:-Ohm¯ OR SI units :- Siemens
  6. Electrode :-It is simple wire like terminal or plate / rod use to pass electricity through the solution & to send electricity generated in solution .

Types of electrodes :-

  • REFERENCE ELECTRODE/ NON-POLARIZABLE ELECTRODES :- An electrodes whose potential remains constant and against which other potentials can be measured: SCE (Saturated calomel electrode),Hydrogen electrode , Ag-Ag CL electorde etc.
  • Indicator/polarizable electrodes :- The electrodes whose potential is a function of the analyte concentration Eg: Glass Electrodes – most widely used, platinum electrodes , metalic electrodes

COMPARISON OF VARIOUS ELECTROCHEMICAL METHOD OF ANALYSIS 

TECHNIQUE CONSTANT PARAMETERS PARAMETERS TO BE MEASURED
Potentiometry current Potential/Voltage
Potentiometry titration Current GRAPH:- Potentials vs ml of titrant
Conductometry Potential Conductance
Conductometry titration Potential GRAPH:- Conductance vs ml of titrant
Polargraphy Concentration GRAPH:-Diffusion current vs applied potentials
Amperometry potential GRAPH:-diffusion currents vs ml of titrant

MCQ

1. 1 mole e¯ =

a.90000 coulomb

b. 96,500 coulomb

c.133300 coulomb

d.96,400 coulomb

2.which type of graph shows in Potentiometry titration ?

a.diffusion currents vs ml of titrant

b.Potentials vs ml of titrant

c.Diffusion current vs applied potentials

d. Conductance vs ml of titrant

3. Which type of graph shows in Amperometry ?

a.diffusion currents vs ml of titrant

b.Potentials vs ml of titrant

c.Diffusion current vs applied potentials

d. Conductance vs ml of titrant

4.which type of graph shows in Conductometry titration ?

a.diffusion currents vs ml of titrant

b.Potentials vs ml of titrant

c.Diffusion current vs applied potentials

d. Conductance vs ml of titrant

5.which is not a reference electrodes ?

a. SCE

b.Ag-Ag CL electrode

c.Hydrogen electrode

d.platinum electrode

6. which is not a Indicator electrodes ?

a. metallic electrodes

b.Glass Electrodes

c.platinum electrodes

d.Hydrogen electrode

ANSWER KEY :-

1.B

2.B

3.A

4.D

5.D

6.D

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