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

Leave a Reply

Your email address will not be published. Required fields are marked *

five × 3 =

Designed & Developed by ThemeXpert