Solutions, Colloids, Crystalloids, Surface tension, Dialysis

SOLUTIONS, COLLOIDS,
SURFACE TENSION,
DIALYSIS
Dr. Subir
Kumar
Mandal

INTRODUCTION
 Solution is a homogenous mixture of two or
more substances (solid, liquid or gases)
distributed uniformly among each other.
 Solvent is the component of a solution which
forms larger portion of that solution e.g. water.
 Solute is the component of a solution which
form minor portion of that solution e.g. sugar.
13-Feb-18 SOLUTIONS- DR. SUBIR KUMAR 2

INTRODUCTION
 Example: 0.9% NaCl solution. Here water is
solvent (represent major portion) & NaCl is
solute (represent minor portion of solution).
 Homogenous mixture is the mixture of two or
more substances of same composition.
 Heterogeneous mixture is the mixture of two
or more substances of different composition in
different parts of the total mixture.

INTRODUCTION
 True solution is a homogenous mixture of
solute and solvent. Here solutes are crystalloid
and exist in the solution as molecules or ions.
 Molar/Molal solution is the solution
containing 1 mole of solute per liter solution/
per kg solvent.
 Normal solution (1 Eq/L) is the solution
containing 1 Eq of solute per liter solution.
 Osmolar/Osmolal solution is the solution
containing 1 osmole of solute per liter
solution/per kg solvent.13-Feb-18 SOLUTIONS- DR. SUBIR KUMAR 4

INTRODUCTION
 Saturated solution is the solution containing
the maximum concentration of solute.
Additional solute will not dissolve in a saturated
solution.
 Supersaturated solution is a solution that has
more solute than it can dissolve at a given
temperature e.g. when salt is added to water
until the rock salt is formed in water.
 Unsaturated solution is the solution which
can dissolve more solute at a given
temperature.13-Feb-18 SOLUTIONS- DR. SUBIR KUMAR 5

a) Unsaturated
soln.
b) Saturated soln.
c) Supersaturated
soln.
 Solution of
Sodium
Acetate.

INTRODUCTION
 Standard solution is the solution that contain
a known and accurate amount (i.e.
concentration) of a substance or element. These
solutions are commonly used to help identify
and determine the concentration of a substance
whose concentration is unknown.
 Percent solution is the solution expressed in
the unit %. It may be percentage by weight-
w/w; percentage by volume- w/v, v/v and
molar concentration.13-Feb-18 SOLUTIONS- DR. SUBIR KUMAR 7

INTRODUCTION
 Tonicity: It’s the net osmolar gradient across
the cell membrane that drives osmosis (water
movement).
 Solutions having tonicity same that of plasma,
are known as Isotonic solutions e.g. 0.9% NaCl
solution, 5% DA (dextrose in aqua), 3.8%
sodium citrate solution etc.
 Solutions having tonicity less than that of
plasma, are called Hypotonic solutions e.g.
Distilled water, 0.45% NaCl solution etc.13-Feb-18 SOLUTIONS- DR. SUBIR KUMAR 8

INTRODUCTION
 Solutions having tonicity more than that of
plasma, are called Hypertonic solutions e.g.
1.5% NaCl solution, 3% NaCl solution etc.
 Normal saline is 0.9% NaCl solution [0.9 g
NaCl in 100 ml solution]. It has osmolarity same
as that of plasma, so it’s isotonic to plasma. It’s
called saline due to presence of NaCl.

CHANGES OF RBC IN
DIFFERENT SOLUTIONS
a) RBC in Hypertonic solution:
 Hypertonic solution has a greater tonicity
than RBC. So, solution will attract more water
from RBC. So, water comes out from RBC, that
will cause shrinkage of RBC.
b) RBC in Hypotonic solution:
 Hypotonic solution has lower tonicity than
RBC. So, more water will move from solution to
RBC & RBC will swell and ultimately blast.

CHANGES OF
RBC IN
DIFFERENT
SOLUTIONS

UNITS OF MEASUREMENT
1) Percentage by weight (w/w): It’s the gram of
solute/100 g solution e.g. 5% dextrose (w/w)
means, 5 g dextrose present in 100 g
solution.
2) Percentage by volume (w/v or v/v): It’s the
gram of solute/100 ml solution (w/v) or the
ml of solute/100 ml solution (v/v) e.g. 5%
dextrose (w/v) means, 5 g dextrose present
in 100 ml solution & 5% alcohol (v/v) means,
5 ml alcohol present in 100 ml solution.13-Feb-18 SOLUTIONS- DR. SUBIR KUMAR 12

3) Molarity: Is the number of mole of solute per
liter solution e.g. 5 molar glucose solution
means, 5 moles glucose present in 1L
solution.
4) Molality: Is the number of mole of solute per
kg solvent e.g. 5 molal glucose solution
means, 5 moles glucose present in 1kg
solvent.
5) Normality: Is the number of equivalent of
solute per liter solution e.g. 2 N HCL means 2
Eq HCL present in 1L solution.13-Feb-18 SOLUTIONS- DR. SUBIR KUMAR 13

6) Osmolarity: Is the number of osmole of solute
per liter solution e.g. 3 osmolar glucose
solution means, 3 osmole glucose present in
1L solution.
7) Osmolality: Is the number of osmole of solute
per kg solvent e.g. 3 osmolal glucose solution
means, 3 osmole glucose present in 1kg
solvent.

SURFACE TENSION Dr. Subir Kumar
Mandal

SURFACE TENSION
 Surface tension is the force with which the
molecules on the surface are held together. It’s
expressed as dynes/cm.
 Surface tension decreases with increasing
temperature i.e. Surface tension 1/α
Temperature.
 Surface tension keeps the liquid surface in a
state of tension and allows the liquid droplets
to contract to the smallest possible area with13-Feb-18 SOLUTIONS- DR. SUBIR KUMAR 16

SURFACE TENSION

SURFACE TENSION
 Application of surface tension:
 Fat digestion- Bile salts decrease the surface
tension of fat and emulsify big fat globules into
minute particles for effective digestion.
 Surfactant & Lung function- Surfactant
decreases surface tension of alveoli and keeps
the alveoli in expand state for efficient
exchange of gases in lungs.

Surfactant &
Lung function

COLLOID &
CRYSTALLOID
DR. SUBIR KUMAR
MANDAL

COLLOIDS
 Thomas Graham (1861),
regarded as the 'father of
colloidal chemistry',
divided substances into
two classes-Crystalloids
and Colloids.
 Colloids (Greek : glue-like)
are the substances with
size 1-100 nm which can’t
pass through the
semipermeable membrane
e.g. protein, glycogen,13-Feb-18 SOLUTIONS- DR. SUBIR KUMAR 21

CRYSTALLOIDS
 Crystalloids are
substances with size less
than 1 nm which can pass
through semipermeable
membrane e.g.
electrolytes, glucose,
amino acid etc.

CLASSIFICATION OF
COLLOIDS
1) Hydrophilic or Lyophilic Colloid:
 Practically all colloids of living cells are
hydrophilic. These are solvent loving and have
affinity to water.
 Therefore, hydrophilic colloids are also called
protective colloid e.g. bile salts keeps
cholesterol & unconjugated bilirubin in
solution. Protein, polysaccharide, gelatin are
common hydrophilic colloids.

CLASSIFICATION OF
COLLOIDS
2) Hydrophobic or Lyophobic Colloid:
 These are solvent hating and have no affinity
to water. They are kept in solution by
hydrophilic colloid adsorbed around them e.g.
colloidal gold, silver.

PROPERTIES OF COLLOIDS
Brownian
movement.
Tyndall
phenomenon.
Electrical
phenomenon.
Surface
phenomenon.

1) Brownian movement:
 Random movement of microscopic particles
suspended in a fluid, caused by collision with
molecules of the surrounding medium. Robert
Brown first observed in 1827, it provided strong
evidence in support of the kinetic theory of
molecules.

2) Tyndall Phenomenon:
 The visibility of floating particles in gases or
liquids when illuminated by a ray of sunlight
and viewed at right angles to the illuminating
ray.
 The scattering of a beam of light when
passed through a medium containing small
suspended particles (as smoky or mist-laden air
or colloidal solutions) — called also Tyndall
phenomenon.13-Feb-18 SOLUTIONS- DR. SUBIR KUMAR 27

SUSPENSION & EMULSION
 Suspension is a heterogeneous mixture of
non-soluble solute with water, where solute
size is more than 1μm e.g. antacid suspension,
RBC in plasma, sand in water, dust in air,
droplets of oil in air. Solutes are visible under a
microscope and can often be seen with the
naked eye.
 Emulsion is a special type of mixture made by
combining two liquids that normally don't mix
(solute size 100-1000 nm). The word emulsion
comes from the Latin word meaning "to milk"

SUSPENSION

SUSPENSION & EMULSION
 The process of turning a liquid mixture into
an emulsion by using emulsifier, is called
emulsification.
 Examples of emulsion: 1) Oil and water
mixtures are emulsions when shaken together.
The oil will form drops and disperse throughout
the water; 2) Egg yolk is an emulsion containing
the emulsifying agent lecithin; 3) Crema on
espresso is an emulsion consisting of water and
coffee oil; 4) Butter is an emulsion of water in
fat; 5) Mayonnaise is an oil in water emulsion
that is stabilized by the lecithin in egg yolk.13-Feb-18 SOLUTIONS- DR. SUBIR KUMAR 31

EMULSION & EMULSIFIER

DIALYSIS
 Dialysis comes from Greek word ‘dialusis’
means dissolution. It is the process of
separation of colloids and crystalloids from
their mixture through a semi-permeable
membrane.
 Dialysis is a process for removing waste and
excess water from the blood. Used as artificial
replacement for lost kidney function.

DIALYSIS
 Principle of dialysis: Crystalloid substances in
solution can pass through semipermeable
membrane while colloid particles cannot. In
dialysis, semipermeable membrane is called
dialyzing membrane or dialyzer, usually in the
form of an elongated tube or of a bag.
 The goal of dialysis is to remove accumulated
fluid and toxins [by diffusive transport (based
on countercurrent flow of blood and dialysate)
& convective transport (solvent drag with
ultrafiltration)] to maintain their concentrations
below the levels at which they produce uremic13-Feb-18 SOLUTIONS- DR. SUBIR KUMAR 34

MODALITIES OF DIALYSIS
1) Peritoneal dialysis
2) Intermittent hemodialysis
3) Hemofiltration
4) Continuous renal replacement therapy
 Decision of modality determined by catabolic
rate, hemodynamic stability, and whether
primary goal is fluid or solute removal.

DIALYZER

HOW DOES DIALYZER CLEAN
BLOOD?
 The dialyzer, or filter, has two parts— one
part for blood and the other part for a washing
fluid called dialysate. A thin membrane
separates these two sides.
 Blood cells, protein and other important
things remain in blood because they are too big
to pass through the membrane. Smaller waste
products such as urea, creatinine and extra
fluid pass through the membrane and are
removed. Dialysis fluid is changed either
periodically or continuously as the crystalloids
diffuse out from interior into dialysis fluid.13-Feb-18 SOLUTIONS- DR. SUBIR KUMAR 38

GIBBS-DONNAN EQUILIBRIUM
 When membrane is freely permeable to ions
(Na+, Cl-) and if the concentration of ions on
both the sides is different, the ions freely
diffuse to attain equal concentration.
 Gibbs-Donnan observed that the presence of
a non-diffusible ion on one side of the
membrane alters the diffusion of diffusible
ions.

 When a semipermeable membrane separates a
solution of non-diffusible ions from another
solution of diffusible ions, equilibrium is
attained with unequal distribution (due to
presence of protein) of diffusible ions across
the semipermeable membrane and at
equilibrium, the product of molar concentration
of diffusible ions on either side of membrane
will be same maintaining the electrical
neutrality on both sides of the membrane.13-Feb-18 SOLUTIONS- DR. SUBIR KUMAR 40

GIBBS-DONNAN EFFECT
 This is the behavior of charged particles in
solutions separated by a semipermeable
membrane, which doesn’t allow some of the
particles to pass. The equilibrium that results is
a balance between the electrostatic forces and
the osmotic forces affecting these ions.
 It’s the effect on the distribution of diffusible
ions between two sides of a semi-permeable
membrane due to the presence of non-
diffusible ions on one side of the membrane.

GIBBS-DONNAN EFFECT
 The Gibbs–Donnan effect is a name for the
behavior of charged particles near a semi-
permeable membrane that sometimes fail to
distribute evenly across the two sides of the
membrane. The usual cause is the presence of a
different charged substance that is unable to
pass through the membrane and thus creates
an uneven electrical charge.

Salient features of Donnan membrane
equilibrium
 The presence of a non-diffusible ion influences the concentration of
diffusibleions across the membrane.
 The concentration of oppositely charged ions (Na+), is greater on the side of
membrane containing non-diffusibleions (Pr-).
 The concentration of similarly charged ions (Cl-) is higher on the side of the
membrane not containing non-diffusible ions (Pr-).
 The net concentration of total ions will be grater on the side of the
membrane containing non-diffusible ions. This leads to a difference in the
osmotic pressure on either side of the membrane.13-Feb-18 SOLUTIONS- DR. SUBIR KUMAR 44

LAW OF MASS ACTION
 Rate of any chemical reaction at any instant, at
a given temperature is directly proportional to
the product of molar concentrations of
reactants. It’s the mathematical expression of
the law of chemical equilibrium.
 At equilibrium macroscopic observables have
stopped changing. The forward and reverse
reaction rates are equal.

LAW OF MASS ACTION
V1
A+B C+D
V2
V1 α [A] [B]
» V1= K1[A] [B] At equilibrium V1=V2
V2 α [C] [D] » K1 [A] [B]= K2 [C] [D]
»V2= K2[C] [D] » [C] [D] / [A] [B]= K1/K2= K

ADSORPTION
 Adsorption is a surface phenomenon. It is the
process of accumulation of a substance
(adsorbate) on the surface of another substance
(adsorbent).
 Adhesion of atoms, ions, or molecules from a
gas, liquid, or dissolved solid to a surface, is
adsorption.
 Adsorbate is the substance which is adsorbed
on the surface.13-Feb-18 SOLUTIONS- DR. SUBIR KUMAR 47

ADSORPTION
 Adsorbent is the substance on which surface
the adsorbate is adsorbed.
 The surface of a liquid or solid is in a state of
strain or unsaturation which results in
unbalanced residual force at the surface These
unbalanced residual forces results in higher
surface energy. Consequently, the surface of
liquids/ solids always have a tendency to attract
and retain the molecular species with which it
comes in contact. This tendency is responsible
for the phenomenon of Adsorption.

TYPES OF ADSORBENTS
1) Oxygen Containing Compounds: Typically
Hydrophilic & Polar e.g. Silica Gel & Zeolites.
2) Carbon Based Compounds: Typically
Hydrophobic & Non Polar e.g. Activated
Carbon & Graphite.
3) Polymer Based Compounds: Polar or Non
polar functional groups in a porous polymer
matrix e.g. Polymers & Resins.

COMMERCIAL ABSORBENTS
 SILICA GEL: Drying of refrigerants , organic
solvents, transformer oils, Desiccants in packing &
double glazing, Dew Point Control of natural Gas.
 ACTIVATED ALUMINA: Drying of gases, organic
solvents, transformer oils, Removal of HCl from
Hydrogen, Removal of fluorine in Alkylation
process.
 ACTIVATED CARBON: Removal of odors from
gases, Recovery of solvent vapors, Nitrogen from
air, Water purification.

COMMERCIAL ABSORBENTS
 POLYMERS & RESINS: Water Purification,
Recovery & purification of steroids & amino
acids, Separation of fatty acids from water &
toluene, Recovery of proteins & enzymes.
 Clay: Treatment of edible oils, Removal of
organic pigments, Refining of mineral oils.

APPLICATIONS OF
ADSORPTION
I. Separation and purification of liquid and gas
mixtures, bulk chemicals, isomers and air.
II. Drying gases and liquids before loading them
in industrial systems.
III. Removal of impurities from liquid and gas
media.
IV.Recovery of chemicals from industrial and
vent gases.

Solutions, Colloids, Crystalloids, Surface tension, Dialysis

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