Conductance of Electrolytic Solutions
1. Introduction:
Electrolytic solutions conduct electricity due to the presence of dissolved ions. The conductance of thes
2. Conductance and Conductivity:
Conductance (G) is the ability of an electrolyte to conduct electricity and is the reciprocal of resistance (
G = 1/R (Siemens, S)
Conductivity (k) is the conductance of a solution per unit length and cross-sectional area:
k = G × (l/A)
where:
- G = Conductance (Siemens, S)
- l = Distance between electrodes (cm)
- A = Cross-sectional area of the solution (cm²)
3. Molar and Equivalent Conductivity:
Molar Conductivity (L_m) is the conductivity per unit concentration:
L_m = κ / C
Equivalent Conductivity (L_eq) is the conductivity per equivalent concentration:
L_eq = κ / N
where:
- C = Molar concentration (mol/L)
- N = Normality (equivalents/L)
4. Factors Affecting Conductivity:
Several factors influence the conductivity of electrolytic solutions:
- Nature of Electrolyte: Strong electrolytes fully dissociate, while weak electrolytes partially dissociate.
- Concentration: Conductivity (κ) decreases with dilution, but molar conductivity (Λ_m) increases.
- Temperature: Conductivity increases with temperature due to increased ion mobility.
- Viscosity of Solvent: Higher viscosity reduces ion movement and lowers conductivity.
5. Kohlrausch's Law:
Kohlrausch's law states that the molar conductivity at infinite dilution (L_m°) is the sum of the individual
L_m° = λ■ + λ■
where λ■ and λ■ are the limiting molar conductivities of the cation and anion, respectively.
6. Applications of Conductance Measurements:
Conductance measurements are widely used in electrochemistry:
1. Introduction:
Electrolytic solutions conduct electricity due to the presence of dissolved ions. The conductance of thes
2. Conductance and Conductivity:
Conductance (G) is the ability of an electrolyte to conduct electricity and is the reciprocal of resistance (
G = 1/R (Siemens, S)
Conductivity (k) is the conductance of a solution per unit length and cross-sectional area:
k = G × (l/A)
where:
- G = Conductance (Siemens, S)
- l = Distance between electrodes (cm)
- A = Cross-sectional area of the solution (cm²)
3. Molar and Equivalent Conductivity:
Molar Conductivity (L_m) is the conductivity per unit concentration:
L_m = κ / C
Equivalent Conductivity (L_eq) is the conductivity per equivalent concentration:
L_eq = κ / N
where:
- C = Molar concentration (mol/L)
- N = Normality (equivalents/L)
4. Factors Affecting Conductivity:
Several factors influence the conductivity of electrolytic solutions:
- Nature of Electrolyte: Strong electrolytes fully dissociate, while weak electrolytes partially dissociate.
- Concentration: Conductivity (κ) decreases with dilution, but molar conductivity (Λ_m) increases.
- Temperature: Conductivity increases with temperature due to increased ion mobility.
- Viscosity of Solvent: Higher viscosity reduces ion movement and lowers conductivity.
5. Kohlrausch's Law:
Kohlrausch's law states that the molar conductivity at infinite dilution (L_m°) is the sum of the individual
L_m° = λ■ + λ■
where λ■ and λ■ are the limiting molar conductivities of the cation and anion, respectively.
6. Applications of Conductance Measurements:
Conductance measurements are widely used in electrochemistry:
