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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
SOLUTIONConcentration
Types of solution
INTRODUCTION
Solution properties
Dialysis
No.1
No.2
No.3
No.4
No.5
SOLUTION
Definition
MATTER
INTRODUCTION
Classification
Mixture
Pure substance
No. 1
State of matter
THE STATE OF MATTER
Matter
Solid Liquid Gas
CLASSIFICATION OF MATTER
Matter
Mixture Pure substance
Homogeneous mixture
Heterogeneous mixture Element Compound
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
Solute Solvent
•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 asolute 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 (NH4NO3 in water)
Exothermic : Solute + Solvent Solution + Heat (NaOH in water)
SOLUTIONConcentration
Types of solution
INTRODUCTION
Solution properties
Dialysis
No.1
No.2
No.3
No.4
No.5
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. Polar2. Semipolar3. 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 hypotonicsolution
Red blood cells with isotonicsolution
Red blood cells with hypertonicsolution
SOLUTIONConcentration
Types of solution
INTRODUCTION
Solution properties
Dialysis
No.1
No.2
No.3
No.4
No.5
SOLUTION
ConcentrationNo. 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
ConcentrationNo. 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 avolumetric scale, the amount of solute per fixed volume of solution, when theconcentration is expressed on a volumetricscale, the amount of solute contained in agiven volume of solution is equal to the product of the volume and the concentration:
Amount of solute = volume x concentration
continued
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:
Volume1 x concentration1 = Volume2 x concentration2
If any three terms in the above equation areknown, the fourth can be calculated. The quantities on both sides of the equation mustbe expressed in the same units
continued
SOLUTIONConcentration
Types of solution
INTRODUCTION
Solution properties
Dialysis
No.1
No.2
No.3
No.4
No.5
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 tb = nKbm• Δ tf = nKfm
Δ t is the boiling point or freezing point difference between pure solvent and solution.
Kb and Kf 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 (C12H22O11) is dissolved in 1.00 kg of
water, Kb = 0.52 0C/m and Kf = 1.86 0C/m
• Answer :
a. To fine the boiling point, calculate solution
molality :
171.0 g (C12H22O11) 1 mol C12H22O11 =
342.0 g C12H22O11
= 0.50 mol C12H22O11
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 tb = nKbm = (1)(0.52 0C/m)(0.50m) = 0,26 0C
d. Δ tf = nKfm = (1)(1.86 0C/m)(0.50m) = 0,93 0C
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.
SOLUTIONConcentration
Types of solution
INTRODUCTION
Solution properties
Dialysis
No.1
No.2
No.3
No.4
No.5
SOLUTION
DialysisNo. 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
dialysat
blood
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.
EDTA : Ethylenediaminetetra-acetic acid
EDTA with Metal
Ca, Fe, etc
COLLOID
Types of colloid
Colloid properties
INTRODUCTIONNo.1
No.2
No.3
COLLOID
INTRODUCTION :° Definition° Diameter of colloid particle
No. 1
• 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:
10ˉ7 to 10 ˉ5 cm (10 – 1000 A˚)
COLLOID
Types of colloid
Colloid properties
INTRODUCTIONNo.1
No.2
No.3
COLLOID
Types of colloid
No.2
TYPES OF COLLOID
Type Name
Examples
Aerosol
FoamEmulsionSolSolid foam
Fog, aerosol sprays, some air pollutantsSmoke, some air pollutantsWhipped cream, shaving creamMilk, mayonnaisePaint, ink, gelatin dessertMarshmallow, pumice stone, foam rubberButter, cheesePearls, opals, colored glass, some metal alloys
Dispersing medium
Dispersed phase
Gas
GasLiquidLiquidLiquidSolid
SolidSolid
Liquid
SolidGasLiquidSolidGas
LiquidSolid
LYOPHOBIC AND LYOPHILIC SYSTEM
Colloidal solutions with a liquid as Dispersion medium can be dividedroughly into two Categories :1. Lyophilic Sols2. Lyophobic Sols
DIFFERENCES BETWEEN
THE TWO TYPES1. 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
Types of colloid
Colloid properties
INTRODUCTIONNo.1
No.2
No.3
COLLOID
Colloid propertiesNo.3
TYNDALL EFFECTBROWNIAN 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
colloid
CuSO4
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 6th Edition, Vol.1-2, Merit Publisher, Multan, 1999