Chapter 11 SUMMARY

Ali Barakat

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By: Ali Barakat

Word Definition

CHAPTER 11

Phase

A homogeneous part of the system in contact with other parts

of the system but separated from them by a well-defined

boundary.

Dipole-dipole

interaction

Attractive forces between polar molecules

(molecules that poses dipole moment).

H-bonding

A strong type of dipole-dipole interaction, formed between

hydrogen atom in a polar molecule and a high-electronegative

atom in another polar molecule (N, O, F).

INTRAMOLECULAR

FORCES

Attractive forces that holds the atoms together within a

molecule.

INTERMOLECULAR

FORCES

Attractive forces between molecules.

Surface tension The amount of energy required to stretch or increase the

surface of a liquid by a unit area.(J/m2)

Viscosity A measure of a fluid’s resistance to flow.

Cohesion The intermolecular attraction between like molecules.

Adhesion The intermolecular attraction between unlike molecules.

Unit cell The basic repeating structural unit of a crystalline solid.

By: Ali Barakat

Molar heat of

vaporization

The energy required to vaporize 1 mole of a liquid at its boiling

point.

Molar heat of

fusion

The energy required to melt 1 mole of a solid substance at its

freezing point.

Critical

temperature

The temperature above which the gas cannot be made to

liquefy, no matter how great the applied pressure

Critical pressure the minimum pressure that must be applied to bring about

liquefaction at the critical temperature

Surfactant A substance added to liquid which decreases its surface tension.

By: Ali Barakat

Highlights

INTRAMOLECULAR FORCES

Attractive forces that holds the

atoms together within a molecule.

Stabilize individual molecules.

Stronger.

INTERMOLECULAR FORCES

Attractive forces between molecules.

Responsible for the bulk properties of

the matter. Boiling point.

Freezing point.

DHvap

DHfus

DHsub

Weaker.

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By: Ali Barakat

By: Ali Barakat

CROSS SECTION OF METALLIC CRYSTALLE

Nucleus &

Inner shell e-

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By: Ali Barakat

T2 > T1

At the higher temperature the curve

flattens out.

The higher the temperature, the

greater the number of molecules

with high kinetic energy.

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1. The strength of ion-dipole force depends on:

Charge and size of the ion.

Size and magnitude of the dipole moment of the polar molecule.

2. Charges of cations are usually more concentrated than anions that have

the same magnitude.

Because cations are usually smaller than anions.

3. Mg2+ interacts more strongly with H2O molecules than Na2+.

Because Mg2+ has a higher charge than Na+.

Because Mg2+ has a smaller ionic radius than Na+.

Heat of hydration of Mg2+ is greater than heat of hydration of Na+.

4. If we placed an ion or a polar molecule near an atom or a nonpolar

molecule, the electron distribution of the atom (or the molecule) will

be distorted by the force exerted by the ion or the polar molecule

resulting in a kind of dipole called induced dipole

Because the separation of positive and negative ions in the atom or

the nonpolar molecule is due to the proximity of an ion or a polar

molecule.

5. Polarizability

The ease with which the electron distribution in the atom or molecule can

be distorted.

6. As electrons are in continuous motion, a nonpolar molecule could have

an instantaneous dipole.

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7. The likelihood of a dipole moment being induced depends on:-

Charge of the ion OR the strength of the dipole.

The polarizability of the atom or the nonpolar molecule.

8. Polarizability increases with:-

Greater number of electrons.

More diffuse electron cloud.

9. Dispersion force ∝ polarizability ∝ Molar mass (GR???) Molecules with larger molar mass tend to have more electrons and

dispersion forces increase in strength by increasing number of electrons.

Larger molar mass means a bigger atom whose electron distribution is more easily distributed because the outer electrons are less tightly held to the nuclei.

Dispersion force ∝ Low Temperature Dispersion force ∝ reduced atomic speed

10. Melting point increases while Molar Mass is increasing.

11. At any moment, the atom could have a dipole moment created by the specific positions of its electron, and it is called instantaneous dipole because it lasts for just a tiny fraction of second.

12. Instantaneous dipoles cancel each other.

13. Dispersion force: attractive forces that arise as a result of temporary dipoles induced in atoms and nonpolar molecules.

14. Surface tension ∝ I.M.F

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15. Polarizability enables gases containing atoms or nonpolar molecules to condense.

16. Cohesion > Adhesion (Mercury)……. Convex meniscus

17. Adhesion > Cohesion (Water)……….. Concave meniscus

18. Surfactant - substance added to liquid which decreases the surface

tension.

19. Viscosity ∝ low temperature ∝ M.M ∝ density ∝ I.M.F

20. Viscosity Units: J/m2 --------- N.s/m2……………….. Kg/(m.s)

21. Surface tension results from the net inward force experienced by the

molecules on the surface of a liquid.

22. Water has maximum density at 40C.

23. In f.c.c

√ ……. √ ..….

√ .…. ….. √

√

24. In b.c.c

√ √

√

√

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25. In s.c.c

26. The equilibrium vapor pressure is the vapor pressure measured when a

dynamic equilibrium exists between condensation and evaporation.

27. A state of dynamic equilibrium, in which the rate of a forward process is

exactly balanced by the rate of reverse process.

28. Molar heat of vaporization (DHvap): is the energy required to vaporize 1

mole of a liquid at its boiling point.

29. Clausius-Clapeyron Equation

(

).

30. Boiling point: the temperature at which the (equilibrium) vapor

pressure of a liquid is equal to the external pressure.

31. Normal boiling point: the temperature at which a liquid boils

when the external pressure is 1 atm.

32. Critical temperature (Tc): the maximum temperature at which

the gas can be made to liquefy, with no effect for raising the

pressure at any temperature above the critical temperature.

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33. The critical pressure (Pc): the minimum pressure that must be

applied to bring about liquefaction at the critical temperature.

34. The melting point of a solid or the freezing point of a liquid is

the temperature at which the solid and liquid phases coexist in

equilibrium.

35. Molar heat of fusion (DHfus): the energy required to melt 1 mole

of a solid substance at its freezing point.

36. Molar heat of sublimation (DHsub): the energy required to

sublime 1 mole of a solid.

37. Due to Hess’s Law: DHsub = DHfus + DHvap

38. A phase diagram summarizes the conditions at which a

substance exists as a solid, liquid, or gas.

39. An increase in the pressure causes the boiling point to increase

and melting point to decrease.

Because, ∝

And so an increase in the pressure of ice favors the liquid phase.

40.

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