__Conductometry__

__Contents__

• Conductometry

• Principle involved

• Measurement of conductivity

• Pros and cons of conductometric titrations

• Precautions to be taken

• Procedure

• Comparison of potentiometry vs conductometry

• Applications

__Objectives__

**By the end of this
session, students will be able to:**

• Define conductometry

• Define and explain the principle involved in

conductometric titrations

• Discuss the pros and cons Conductometry

• Explain precautions to be taken for conductometric

titrations

• Brief the applications of conductometric titrations

__Conductometry__

• Measurement of conductivity of a solution

• Due to mobility of cations and anions towards respective

electrodes

• Conductivity (C) is inversely proportional to resistance

(R) of a solution

**C = 1/R**

• Unit of conductivity is mhos or ohms-1

• Conductivity of a solution depends upon-

o

Number of ions (concentration)

o

Charge of ions

o

Size of ions

o

Temperature

• Resistance of a solution is given by

**R = E/I**

Where E = potential difference

I = current which flows through

Unit of resistance (R) is ohms

Potential difference (E) is volts

Current (I) is amperes

• Resistance of a solution depends upon length (l) and cross

resistance (a) of the conductor through which conductivity takes place

**R = ρl/a**

• ρ is specific resistance

• **Specific resistance
(ρ)** is the resistance offered by a substance of 1cm length and 1 sq.cm

surface area, Unit of measurement is ohm cm

• **Specific
conductivity (kv)** is the conductivity offered by a substance of 1cm length

and 1 sq.cm surface area, Unit of measurement is mhos cm-1

• **Equivalent
conductivity (λv)** is the conductivity of a solution containing equivalent

weight of the solute between electrodes 1 cm and 1 sq.cm, Unit of measurement

is mhos cm-1

**• Molar conductivity
(μv)** is the conductivity of a solution containing molecular weight of the

solute between electrodes 1 cm apart and 1 sq.cm surface area

• Molar conductivity = specific conductivity x volume of

solution containing one molecular weight of the electrolyte

__Measurement
of Conductivity __

• Conductivity may be measured by applying an alternating

electrical current (I) to two electrodes immersed in a solution and measuring

the resulting voltage (V)

• Cations migrate to the negative electrode, the anions to

the positive electrode and the solution acts as an electrical conductor