Topic 10 - the concept of specific and equivalent conductivity, their correlations with the dissociation Flashcards
Comparison of electronic (metallic) and ionic (electrolytic) conductors
What is resistance?
The property that measures the obstruction to the flow of current
What is resistance?
R = ρ x (l/a)
where ρ (rho) is a constant of proportionality and is called specific resistance or resistivity. Its unit is Ohm (Ω).
What is specific resistance?
the resistance between opposite faces of a one-centimetre- edge cube of the conductor
The formula for Conductivity (C). Give the formula
The reciprocal of resistance (R).
Its unit is Siemens (S); 1 S = 1/ Ω
What is Specific conductance? Give the formula
It is the conductance of a cube whose edges are 1 cm long.
Specific conductance (κ, kappa) is the reciprocal of specific resistance (ρ)
What is Specific conductance? Give the formula
Specific conductance (κ, kappa) is the reciprocal of specific resistance (ρ)
5 factors influencing the specific conductance (κ)
- Concentration of ions
- Charge of ions
- Mobility of ions (size and hydrate coat)
- Nature and viscosity of the solvent
- Temperature
What is equivalent conductance?
The conductance of all ions produced by 1 mol (or 1 gram-equivalent) solute placed between two electrodes spaced 1 cm apart
→ denoted by the symbol Λ (lambda)
What is the formula of equivalent conductance?
Λ = κ x volume in ml containing 1 mol (1 g-equivalent) solute
Λ is the symbol for equivalent conductance
What is the dissociation degree for weak electrolytes
The ratio of molar (equivalent) conductance at a given concentration to molar (equivalent) conductance at invite dilution (near zero concentration)
