Presentation on theme: "SOLUTION AND COLLOID SPECIFIC LEARNING OBJECTIVE At the end of the session the student should be able to explain: -Definitions of Solution and Colloids."— Presentation transcript:
SOLUTION AND COLLOID SPECIFIC LEARNING OBJECTIVE At the end of the session the student should be able to explain: -Definitions of Solution and Colloids -System of Solutions and Colloids -Type of Solutions and Colloids
HOMOGENEOUS MIXTURE Homogenous mixtures called solutions And Their distant relatives, colloidal suspensions
Solutions Solutions are homogeneous mixtures of two or more substances in which the components are present as atoms, molecules, or ions These uniformly distributed particles are too small to reflect light, and as a result solutions are transparent (clear) – light passes through them
SUBSTANCES OF SOLUTIONS Solutions SoluteSolvent The substance is dissolved in a solvent is called solute The most abundant substance in a solution is called solvent
SOLUTE Solute Electrolyte A solute that when dissolved in water forms a solution that conducts electricity. Nonelectrolyte A solute that when dissolved in water forms a solution that does not conduct electricity.
HEATS OF SOLUTION Heat is usually absorbed or released when a solute dissolves in a solvent. 1.The process is endothermic, if heat is absorbed, and solution becomes cooler. 2.The process is exothermic, if heat is released, and solution temperature increases. Endothermic : Solute + Solvent + Heat Solution (NH 4 NO 3 in water) Exothermic : Solute + Solvent Solution + Heat (NaOH in water)
SOLUTION Types of solution Medical termChemical term No. 2 Unsaturated Saturated Super saturated Hypotonic Isotonic Hypertonic
Classification of Solubility Three classify of solubility of a compound 1. Soluble 2. slightly soluble 3. insoluble SOLUBILITY Chemical term
Soluble substances dissolve completely in the solvent and form solution Insoluble substances do not dissolve in the solvent The term immiscible is used to describe a liquid solute that does not dissolve in a liquid solvent
Depend on the Polarity Three type of polarity of a compound : 1. Polar 2. Semipolar 3. Nonpolar 1. Soluble SOLUBILITY 2. slightly soluble 3. insoluble
UNSATURATED, SATURATED AND SUPERSATURATED SOLUTIONS Saturated solution, is a solution that contains the maximum amount of a solute in a given solvent, at a specific temperature. Unsaturated solution, is a solution that contains less solute that it has the capacity to dissolve. Supersaturated solution, contains more solute than is present in a saturated solution SOLUBILITY
SUPERSATURATED SOLUTIONS Supersaturated solutions are usually prepared by forming a nearly saturated solution at a high temperature and then slowly cooling the solution to a lower temperature at which the solubility is lower. Such solutions are not stable. The addition of small amount of solid solute (or even a dust particle) will usually cause the excess solute to crystallize out of solution until the solution becomes saturated.
CRYSTALLIZATION CONVERTS A SUPERSATURATED SOLUTION TO A SATURATED SOLUTION A supersaturated Seed crystal is added After excess solute is solution and induces rapid crystallized, the crystallization remaining solution is saturated
SOLUTION Types of solution Medical termChemical term No. 2 Unsaturated Saturated Super saturated Hypotonic Isotonic Hypertonic
Hypotonic, Isotonic and Hypertonic solutions Hypotonic solutions : the solution with the lower concentration of solute If the concentration of water in the medium surrounding a cell is greater than that of the cytosol. Water enters the cell by osmosis Isotonic solutions : the solution being compared have equal concentration of solutes. When red blood cells are placed in a 0.9% salt solution, they neither gain nor lose water by osmosis Hypertonic solutions : The solution with the higher concentration of solutes. If red cells are placed in sea water (about 3% salt), they lose water by osmosis and the cells shrivel up. Medical term
Red blood cells in the Hypotonic, Isotonic and Hypertonic solutions Red blood cells with hypotonic solution Red blood cells with isotonic solution Red blood cells with hypertonic solution
SOLUTION Concentration No. 3 Molarity (M)Percent (%) Percent : a solution concentration that expresses the amount of solute in 100 parts of solution. Molarity (M) : a solution concentration that is expressed in term of the number of moles of solute contained in a liter of solution. continued to next slide
SOLUTION Concentration No. 3 Molality (m)Normality (N) Normality (N) : a solution concentration that is expresses in term of the number of gram equivalent of solute contained in a liter of solvent. Molality (m) : a solution concentration that is expressed in term of the number of moles of solute contained in a kilogram of solvent. continued to next slide
Continuation : Weight/weight percent : a concentration that expresses the mass of solute contained in 100 mass units of solution. Weight/volume percent : a concentration that expresses the grams of solute contained in 100 ml of solution. Volume/volume percent : a concentration that expresses the volume of liquid solute contained in 100 volume of solution.
DILUTION The volumetric scales of concentration are those, like molar concentration and normality, in which the concentration is expressed on a volumetric scale, the amount of solute per fixed volume of solution, when the concentration is expressed on a volumetric scale, the amount of solute contained in a given volume of solution is equal to the product of the volume and the concentration: Amount of solute = volume x concentration continued
If a solution is diluted, the volume is increased and the concentration is decreased, but the total amount of solute is constant. Hence, two solutions of different concentrations but containing the same amounts of solute will be related to each other as follows: Volume 1 x concentration 1 = Volume 2 x concentration 2
If any three terms in the above equation are known, the fourth can be calculated. The quantities on both sides of the equation must be expressed in the same units continued
SOLUTION Colligative properties ( continued to next slide) No. 4 SOLUTION PROPERTIES Electrical conductivity and colligative properties
COLLIGATIVE PROPERTIES The properties that depend only on the concentration of solute particles present and not on the actual identity of the solute. Three closely related colligative properties are 1. Vapor pressure 2. Boiling point 3. Freezing point 4. Osmotic pressure
The equation for calculated the boiling point or freezing point difference between pure solvent and solution Δ t b = nK b m Δ t f = nK f m Δ t is the boiling point or freezing point difference between pure solvent and solution. K b and K f are constants characteristic of the solvent used in the solution.
for example : Calculate the boiling and freezing points of the following solutions 171.0 g of sugar (C 12 H 22 O 11 ) is dissolved in 1.00 kg of water, Kb = 0.52 0 C/m and Kf = 1.86 0 C/m Answer : a. To fine the boiling point, calculate solution molality : 171.0 g (C 12 H 22 O 11 ) 1 mol C 12 H 22 O 11 = 342.0 g C 12 H 22 O 11 = 0.50 mol C 12 H 22 O 11 m = moles of solute/1 kg of solvent = 0.50 mol/1.0 kg = 0.50 mol/kg continued to next slide x
Continuation: b. Determine n : because sugar does not dissociate upon dissolving, n = 1. c. Δ t b = nK b m = (1)(0.52 0 C/m)(0.50m) = 0,26 0 C d. Δ t f = nK f m = (1)(1.86 0 C/m)(0.50m) = 0,93 0 C
OSMOTIC PRESSURE Is the hydrostatic pressure required to prevent the net flow of solvent through a semipermeable membrane into a solution. Osmotic pressure ( ) = nMRT (van’t Hoff equation) T = temperature in Kelvins R = the ideal gas constant (0.82 L-atmosphere/degree.mole) M = the solution molarity
OSMOSIS The process in which solvent flows through a semipermeable membrane into a solution.
SOLUTION Dialysis No. 5 Earlier we discussed semipermeable membranes that selectively allow solvent to pass but retain dissolved solutes during osmosis. Dialysis, another membrane process, is also important in living organisms.
Continuation Dialyzing membranes : A semipermeable membranes with pores large enough to allow solvent molecules, other small molecules, and hydrat ions to pass through (are semipermeable membranes with larger pores than osmotic membranes).
Continuation Dialysis : A process in which solvent molecules, other small molecules, and hydrat ions pass from a solution through a membrane (is the passage of ions and small molecules through such membranes).
DIALYSIS. This is one method of dialysis used to purify proteins
Application of Dialysis Scheme of dialysis process Dialysis tubing Dialysate + waste product Fresh dialysate
A similar technique is used to clean the blood of people suffering kidney mal function The blood is pumped through tubing made of a dialyzing membrane. The tubing passes through a bath in which impurities collect after passing out of the blood. Blood proteins and other important large molecules remain in the blood.
HEMODIALYSIS Scheme of hemodialysis process dialysat blood
Continuation Dialysis is most commonly used to remove salts and other small molecules from solutions of macromolecules. During the separation and purification of biomolecules, small molecules are added to selectively precipitate or dissolve the desire molecule.
Continuation Dialysis is also useful for removing small ions and molecules that are weakly bound to biomolecules. Protein cofactors such as NAD, FAD, and metal ions can be dissociated by dialysis. The removal of metal ions is facilitated by the addition of a chelating agent (EDTA) to the dialysate. Minerals are bound by EDTA, these are: Ca, Fe, etc.
colloids (or colloidal suspensions) are homogeneous mixture of two or more components in which there is more of one component than of the others. Definition In solutions the terms solvent and solute are used for the components, but in colloids the terms dispersing medium (for solvent) and dispersed phase (for solute) are used.
DIAMETERS OF THE DISPERSED PHASE The dispersed phase of colloids is made up of much larger particles (very large molecules or small pieces of matter) with diameters: 10ˉ 7 to 10 ˉ 5 cm (10 – 1000 A˚)
TYPES OF COLLOID Type Name Examples Aerosol Foam Emulsion Sol Solid foam Fog, aerosol sprays, some air pollutants Smoke, some air pollutants Whipped cream, shaving cream Milk, mayonnaise Paint, ink, gelatin dessert Marshmallow, pumice stone, foam rubber Butter, cheese Pearls, opals, colored glass, some metal alloys Dispersing medium Dispersed phase Gas Liquid Solid Liquid Solid Gas Liquid Solid Gas Liquid Solid
LYOPHOBIC AND LYOPHILIC SYSTEM Colloidal solutions with a liquid as Dispersion medium can be divided roughly into two Categories : 1.Lyophilic Sols 2.Lyophobic Sols
DIFFERENCES BETWEEN THE TWO TYPES 1.SURFACE TENSION SIMILAR TO THAT OF DISPERSION MEDIUM. 2.VISCOSITY SIMILAR TO THAT OF MEDIUM. 3.SMALL QUANTITIES OF ELECTROLYTES CAUSE PRECIPITATION. 4.THE PARTICLES ARE EASILY DETECTED IN THE ULTRAMICROSCOPE. 5.THE PARTICLES MIGRATE IN ONE DIRECTION IN AN ELECTRIC FIELD. 1.SURFACE TENSION OFTEN LOWER THAN THAT OF DISPERSION MEDIUM. 2.VISCOSITY MUCH HIGHER THAN THAT OF MEDIUM. 3.SMALL QUANTITIES OF ELECTROLYTES HAVE LITTLE EFFECT, BUT LARGE AMOUNTS MAY CAUSE SALTING OUT. 4.THE PARTICLES CANNOT BE READILY DETECTED IN THE ULTRAMICROSCOPE. 5.THE PARTICLES MAY MIGRATE IN EITHER DIRECTION OR NOT AT ALL IN ELECTRICAL FIELD.
COLLOID Colloid properties No.3 TYNDALL EFFECT BROWNIAN MOVEMENT COLLOID DESTRUCTION COLLOID FORMATION EMULSIFYING AGENTS OR STABILIZING AGENTS
TYNDALL EFFECT When a beam of light passes through them, they will be scattered the light, and the path of the light becomes visible. And hence it is generally called the Tyndall effect.
The light beam passes from left to right through a purple gold sol (a colloid), a blue copper sulfate solution, and colloidal iron (III) hydroxide. The light path can be seen in both colloids, but not in the copper sulfate solution. source colloidCuSO 4 Fe(OH) 3
BROWNIAN MOVEMENT As is to be expected, because of their small size, colloidal particles are seen in the ultramicroscope to display vigorous Brownian movement.
COLLOID FORMATION AND DESTRUCTION Much of the interest in colloids is related to their formation or destruction. Colloid particles tend to attract and absorb ions that are present in the dispersing medium. The charge (+ or -) of the adsorbed ions depends on the nature of the colloid, but all colloid particles within a particular system will attract only one charge or the other. This repulsion help prevent the particles from coalescing into aggregates large enough to settle out.
Emulsifying agents is substances that stabilize the colloids (prevented from coalescing) For examples : 1. Egg : the compound in the egg yolk acting as the emulsifying agents 2. Soaps and detergents 3. Etc (CMC = carboxyl methyl cellulose ) EMULSIFYING AGENTS OR STABILIZING AGENTS
Summary Reference: Mushtaq Ahmad, Essentials of Medical Biochemistry 6 th Edition, Vol.1-2, Merit Publisher, Multan, 1999