topic 5 Flashcards
Microheterogeneous systems, colloidal state, colloidal size.
1.s refer to mixtures or solutions where microscopic regions or domains differ in composition, structure, or properties/exhibit variations at a scale smaller than what can be resolved with conventional optical microscopy./ ex: emulsions (oil-in-water or water-in-oil), micelles (aggregates of surfactant molecules)/ fog - intermediate particles , visisble & stay suspended
2.Colloidal state: dispersion system where one substance (the dispersed phase) is finely dispersed in another substance (the dispersion medium)
3.Colloidal size:range in size from 1 nanometer (nm) to 1 micrometer (µm)./ undergo Brownian motion due to collisions with molecules of the dispersion medium./ influences the stability
Tyndal effect
- phenomenon where light is scattered or dispersed by colloidal particles or particles that are larger than the wavelength of visible ligh
- scattered light makes the path of the light beam visible, appearing as a visible cone or beam of light passing through the medium.
- ## effect is used to distinguish between true solutions (where particles are very small and do not scatter light) and colloids or suspensions (where particles are larger and scatter light, making the beam visible).
Types of Colloids
can be classified based on their interaction with water:
1.Hydrophobic Colloids: Insoluble or poorly soluble in water.
Tend to aggregate and form clusters.
Example: Oil droplets in water.
2.Hydrophilic Colloids: Soluble or readily dispersible in water.
Interact well with water molecules.
Example: Sugar or salt dissolved in water.
3.Dispersed or Sol Colloids: Solid particles dispersed in a liquid medium (usually water).
Remain suspended due to Brownian motion and repulsive forces.
Example: Milk, ink, clay in water.
4.Macromolecular Colloids: Dispersed phase consists of large molecules or macromolecules.
Stable dispersions due to high molecular weight.
Example: Starch or cellulose in water.
5.Association Colloids (Micelles):
Formed by aggregation of surfactant molecules or amphiphilic compounds.
Have hydrophobic cores and hydrophilic shells.
Example: Soap micelles in water.
Homogeneous systems: solutions. Saturated and unsaturated solutions.
-A solution is a homogeneous mixture composed of a solute dissolved in a solvent.uniformly distributed at a molecular level.
1.Saturated: solution that contains the maximum
amount of solute that can dissolve at a given temperature and pressure. Any additional solute added
will not dissolve and will remain as undissolved solid.
An unsaturated solution, on the other hand, can
dissolve more solute if added.
Solubility and the
molecular structure.
The solubility of a solute in a solvent depends on the nature of the
solute and solvent and the intermolecular forces between them. Like dissolves like is a general rule that suggests substances with similar polarities and intermolecular forces tend to be more soluble in
each other. Polar solutes dissolve in polar solvents, while nonpolar solutes dissolve in nonpolar
solvents.
Effects of Temperature and Pressure on Gas Solubility:
The solubility of gases in liquids is influenced
by temperature and pressure. As temperature increases, the solubility of gases generally decreases,
and as temperature decreases, solubility increases. Pressure has a direct effect on the solubility of
gases in liquids, with higher pressures leading to higher gas solubility.
Concentration of Solutions
The concentration of a solution refers to the amount of solute present in a
given amount of solvent or solution.
It can be expressed in various ways, including:
* Mass Percent: The mass of solute divided by the total mass of the solution, multiplied by 100.
- Molarity,M: The number of moles of solute per liter of solution.
- Molality, m: The number of moles of solute per kilogram of solvent.
- Volume Percent: The volume of solute divided by the total volume of the solution, multiplied
by 100.
Osmosis and its Biological Importance
-Osmosis is the movement of solvent molecules (usually water) across a semipermeable membrane from a region of lower solute concentration to a region of higher solute concentration, to equalize concentrations.
-Biological Importance:
Cell Function: Essential for maintaining proper cell turgor pressure and preventing excessive water loss or gain.
Plant Cells: Helps in uptake of water and nutrients from the soil through roots.
Animal Cells: Controls water balance and prevents cells from bursting or shrinking due to osmotic pressure.
Kidney Function: Critical for urine formation and regulation of body fluid levels by controlling water reabsorption.
Biotechnological Applications: Used in processes like dialysis to filter waste products from blood.
ex:Red blood cells in hypotonic solution swell and may burst (hemolysis).
