physical chemistry

1. Physical Chemistry
Dr Eman Badr
Professor of Medical Biochemistry and
Molecular Biology
Faculty of Medicine- Menoufia University
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2. What is the Matter
• Matter is any substance that has mass and takes up
space by having volume.
•
• Classification of Matter
•
• Any matter can exist in one of 3 States
(a) Gas (b) Liquid (c) Solid
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3. Classification of Matter
1. Solid matter is composed of tightly
packed particles. A solid will retain its
shape; the particles are not free to move
around.
2. Liquid matter is made of more loosely
packed particles. It will take the shape of
its container. Particles can move about
within a liquid, but they are packed
densely enough that volume is
maintained.
3. Gaseous matter is composed of
particles packed so loosely that it has
neither a defined shape nor a defined
volume. A gas can be compressed.

4. Types of Matters
• A pure substance is a single kind of matter that cannot be
separated into other kinds of matter by any physical means.
• A mixture (not pure substance) is a material made up of two
or more different chemical substances which are not
chemically bonded. can usually be separated back into its
original components.

5. Matter Flowchart
MATTER
Can it be physically
separated?
Homogeneous
Mixture
(true solution)
Heterogeneous
Mixture Compound Element
MIXTURE PURE SUBSTANCE
yes no
Can it be chemically
decomposed?
no
yes
Is the composition
uniform?
no
yes
Colloids Suspensions
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6. Solutions
Solutions, in chemistry, are homogeneous
mixtures of two or more substances.
The substance present in largest quantity usually
is called the solvent.
The substance that is present in smallest quantity
is said to be dissolved and is called the solute.
The solute can be either a gas, a liquid, or a
solid.

7. Solution
• a mixture of two or more substances that is
composed of solutes and solvents
the substance in the smallest
amount and the one that
dissolves in the solvent
the substance in the larger
amount that dissolves the
solute
(solute) Water
(solvent)
(solution)
Salt water is
considered a
solution. How
can it be
physically
separated?

8. Expression of concentration of
solutions
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9. MOLAR VS MOLAL
• One mole of a solute (MW) dissolved
and made up in 1 liter of solvent
(1000ml) is a 1M (one molar solution)
• One mole of a solute (MW) dissolved
in 1 kilogram of solvent (1000g) is a
1m (one molal solution)

10. Normal solutions (N)
• These are solutions containing one gram
equivalent (g Eq) of the substance per
liter. One gram equivalent is the equivalent
weight of the substance expressed in
grams.

11. Types of solutions
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12. 1-True Solutions(crystalloids)
• Very small particle size: .01 nm-1 nm
• Do not separate upon standing
• Are transparent
• Cannot be separated by filtration
• Particles do not display the Tyndall Effect:
the particles are too small to scatter light

13. 2- Colloidal soultions
• A heterogeneous mixture
• May or may not be transparent
• Medium particle size: 1 nm -200 nm
• Do not separate upon standing
• Cannot be separated by filtration
• Particles display the Tyndall Effect: the particles
are large enough to scatter light

14. Examples of Colloids
• Gelatin in H2O
• Milk
• Clouds

15. 3- Suspensions
• A heterogeneous mixture
• Are not transparent
• Large particle size: over 200 nm
• Particles settle out
• Can be separated by filtration
• May or may not display the Tyndall Effect

16. Examples of Suspensions
• Clay in H2O
• Cooking oil in H2O
• Spoiled milk

17. 17
Hydrophilic and Hydrophobic Colloids
Hydrophilic: water-loving
(emulsoids)
Hydrophobic: water-fearing
(suspensoids)
Stabilization of a hydrophobic colloid

18. Types of colloids
Emulsoids Suspensoids
Lyophilic (solvent loving). Lyophobic (solvent fearing).
Stabilized by the presence of
charges and a film of solvent
around solute particles.
Stabilized by the presence of charges
around solute particles only.
Thus precipitation is difficult. Easily precipitated.
Can be redissolved by adding
excess solvent.
If precipitated, they cannot be
redissolved.
Have higher viscosity and lower
surface tension than their solvent.
Have the same viscosity and surface
tension as their solvent.
Some emulsions form gels. Cannot form gels.
Ex; starch and protein in water. Ex; gold and ferric hydroxide in water.

19. Properties of Colloids
1-Tyndall effect
– when a strong beam of light is
passed through a colloidal
sol, the path of light is
illuminated (a visible cone
formed).
- This phenomenon resulting
from the scattering of light by
the colloidal particles.

20. Properties of Colloids
2-Brownian motion
- The zig-zag movement of colloidal particles
continuously and randomly.
• This brownian motion arises due to the
uneven distribution of the collisions
between colloid particle and the solvent
molecules.
- Brownian movement was more rapid for
smaller particles.
- It decrease with increase the viscosity of
the medium.

21. 3- Dialysis:
- Semipermeable cellophane
membrane prevent the
passage of colloidal particles,
yet allow the passage of
small molecules or electrolytes.

22. 4-ULTRACENTRIFUGATION
Involves the use of
the centrifugal force.
More dense
components migrate
away. Solid particles
remain on the bottom.

23. 5-Precipitation of colloids
• This is obtained by:
1- Addition of concentrated electrolytes
- The precipitation power is directly related to the hydration of
the ion and its ability to separate water molecules from
colloidal particles
2- addition of Alcohol + diluted electrolytes

24. .
6-ADSORPTION and Elution
Adsorption is the process in which matter is
extracted from one phase and
concentrated at the surface of a second
phase. (Interface accumulation).
elution is the process of extracting one
material from another by washing with a
solvent; as in washing of loaded ion-
exchange resins to remove captured ions

25. Adsorption Mechanism
– 2) Chemical adsorption
• Results from a chemical interaction between the
adsorbate and adsorbent. Therefore formed bond
is much stronger than that for physical adsorption
• Heat liberated during chemisorption is in the range
of 20-400 kj/g mole
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26. 7- Gelation
• Emulsoids can form gels (change from
liquid state to semisolid state) by
• Lowering the temperature.
• Increasing the concentration.
• Changing the PH.