OIA1008 ELECTRICAL PROPERTIES & EDL

What are electrolytic solutions?

Solutions that conduct electricity due to the presence of free-moving ions.

Example of an electrolytic solution in medicine?

0.9% NaCl (saline) used for intravenous hydration.

What does ionization mean in electrolytes?

The process of a substance breaking into ions in a solution, enabling conductivity.

Difference between strong and weak electrolytes?

Strong electrolytes completely ionize in water; weak electrolytes only partially ionize.

Give one example of a strong electrolyte.

HCl (hydrochloric acid).

Give one example of a weak electrolyte

Acetic acid (CH₃COOH).

What kind of electrolyte is used in oral rehydration salts (ORS)?

Strong electrolytes like Na⁺ and K⁺ salts.

Define electrical conductance (G).

The ability of a solution to conduct electricity; G = 1/R.

What is specific conductance (κ)?

Conductance of 1 cm³ of a solution between electrodes 1 cm apart.

Unit of specific conductance?

S·cm⁻¹ (Siemens per cm).

What is molar conductance (Λm)?

Conductance of all ions produced by one mole of electrolyte in solution.

Formula for molar conductance?

Λm = κ / C, where C is concentration in mol·L⁻¹.

State Kohlrausch’s Law.

At infinite dilution, each ion contributes independently to the total molar conductance.

Why is Kohlrausch’s Law useful?

Helps calculate the limiting molar conductance of weak electrolytes.

How is Λm∞ used in practical settings?

Determines ion concentrations in blood and urine tests.

What does Ostwald’s dilution law explain?

The degree of dissociation (α) of weak electrolytes increases with dilution.

Formula linking Ka to α and C?

Ka = α²C / (1 − α)

How does temperature affect conductance?

Increases ion mobility and thus conductance.

How does concentration affect conductance?

Decreasing concentration usually increases molar conductance.

Why does conductance decrease at high concentrations?

Ion-ion interactions reduce mobility.

What is a colloid?

A heterogeneous mixture with dispersed particles (1–1000 nm) in a continuous medium.

Define a sol.

A colloid where solid particles are dispersed in a liquid.

Example of a medical sol?

Silver sol used as antiseptic in wound dressings.

Why do colloids exhibit electrical properties?

Due to the presence of electric charges on colloidal particles.

What is electrophoresis?

Movement of colloidal particles under an electric field.

Medical application of electrophoresis?

Used in protein or DNA separation in diagnostics (e.g., hemoglobin electrophoresis).

What is electro-osmosis?

Movement of the dispersion medium under an electric field, while particles remain stationary.

What causes charge on colloidal particles?

Adsorption of ions from the medium.

What is the electrical double layer?

Layers of charged ions surrounding a colloidal particle, stabilizing it.

What is coagulation of colloids?

The process by which colloidal particles aggregate and settle.

How is coagulation induced?

By adding electrolytes or changing pH.

Application of coagulation in medicine?

Blood coagulation involving fibrin network formation.

What is Hardy-Schulze rule?

Greater valency of oppositely charged ion = higher coagulating power.

What is conductometric titration?

Titration method that measures conductivity to find the equivalence point.

Which acid-base titration can be monitored via conductometry?

HCl vs NaOH.

What happens to conductivity during strong acid-strong base titration?

Decreases at first (H⁺ replaced by Na⁺), then increases after equivalence (excess OH⁻).

Unit of molar conductance (Λm)?

S·cm²·mol⁻¹

What is the conductance of pure water?

Very low; ~5.5 × 10⁻⁶ S·cm⁻¹

Why are electrolyte tests important in medicine?

Help diagnose dehydration, kidney function, acid-base balance.

How does IV fluid composition affect electrical properties in the body?

Alters blood ionic balance, pH, and conductance—key in emergencies.