(Chem 210) Chap. 11- Liquids, Solids, And Intermolecular Forces

Front 1

Mater exists primarily in 3 phases:

Back 1

- solids
- liquids
- gas

Front 2

Intermolecular Forces:

Back 2

[attractive forces that exist between all molecules & atoms]

- forces that hold many liquids & solids

- responsible for the very existence of the condensed phases.

Front 3

Thermal Energy:

Back 3

the energy associated with the random motion of matter.

Front 4

Table 11.1: Shows the density & molar vol. of water in its 3 different phases, along with molecular representation of each phase

Back 4

Front 5

Table 11.2: Properties of the Phases of Matter

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Front 6

In what two orders can a solid be?

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1- Crystalline

2- Amorphous

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Crystalline:

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The atoms or molecules that compose them are arranged in a well-ordered 3D array

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Amorphous:

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the atoms or molecules that compose them have no long-range order.

Front 9

Shows the 3 states of matter and the changes in conditions that commonly induce transitions between them

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Shows the 3 states of matter and the changes in conditions that commonly induce transitions between them

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Front 11

Gases are Compressible

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Front 12

Conceptual Connection 11.1: Phase Changes

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(A) When water boils, it simply changes phases from liquid to gas. Water molecules do not decompose during boiling.

Front 13

Intermolecular forces are the result of:

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Smaller charges interacting at greater distances

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Dispersion Force (AKA London Force)

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- present in all molecules & atoms

- result of fluctuations in the e- distribution w/ in molecules or atoms.

Front 15

Instantaneous Dipole/ Temporary Dipole:

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at an instant, one side of the atom will be slightly (-) while other side w/ no e-s will be slightly (+).

will induce an instantaneous dipole on its neighboring atom b/c the (+) end of the instantaneous dipole attracts e-s in the neighboring atoms.

(cont. from atom to atom... creating the dispersion force)

Front 16

What does the magnitude of the dispersion force depend on?

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- how easily the e-s in the atom/ molecule can move or polarize in response to an instantaneous dipole.

--------> depends on the size (vol) of the e- cloud

Front 17

Why do larger molecules have greater dispersion force?

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because they have larger e- clouds

e- are held less tightly by the nucleus & can therefore polarize easier.

Front 18

How to determine whether a molecule is polar:

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1) determine whether the molecule contains polar bonds

2) determine whether the polar bonds add together to form a net dipole moment.

Front 19

Characteristics of polar molecules:

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- high melting pts.

- high boiling pts.

- dispersion forces

- dipole-dipole forces

Front 20

The relationship between dipole moment and boiling pt.

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Front 21

Miscibility:

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the ability to mix without separating into two phases - of liquid.

"like dissolves like"

Front 22

In what elements does h-bonding occur?

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- Fluorine (F)
- Oxygen (O)
- Nitrogen (N)

Front 23

Hydrogen bond:

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a strong attraction between the hydrogen in each molecule & the F,O,N on its neighbors.

Front 24

graph showing relation of H-bond and other molecules with their molecular mass and boiling pt.

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Front 25

Ion-dipole force:

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- occurs when an ionic compound is mixed w/ a polar compound

- is especially important in aqueous solutions of ionic compounds.

Front 26

Types of Intermolecular Forces:

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Front 27

surface tension of a liquid:

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the energy required to increase the surface area by a unit amount.

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If intermolecular forces decrease, surface tension will?

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decrease

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Viscosity:

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the resistance of a liquid to flow

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as intermolecular forces increase, viscosity will?

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increase

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as temperature increases, viscosity will?

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decrease

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Capillary action:

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the ability of a liquid to flow against gravity up a narrow tube.

- results from a combination of cohesive forces, and adhesive forces.

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cohesive forces:

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the attraction between molecules in a liquid

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adhesive forces:

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the attraction between theses molecules and the surface of the tube

Front 35

Vaporization:

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the process by which thermal energy can overcome intermolecular forces & produce a phase change from liquid to gas.

- the phase transition from liquid to gas

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Condensation:

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the phase transition from gas to liquid.

Front 37

as temperature increase, vaporization?

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increases

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as intermolecular forces decrease, vaporization?

Back 38

increases

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as surface area increases, vaporization?

Back 39

increases

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volatile liquids:

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vaporize easily

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nonvolatile liquids:

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do not vaporize easily

Front 42

summarizing the process of vaporization:

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- the rate of vaporization increases with increasing temperature

- the rate of vaporization increases with increasing surface area

- the rate of vaporization increases with decreasing strength of intermolecular forces.

Front 43

energy distribution curve

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Front 44

why is vaporization endothermic?

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because it take energy to vaporize the molecules in a liquid

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why is condensation exothermic?

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because heat is released when a gas condenses to liquid.

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heat of vaporization:

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- the amount of heat required to vaporize one mole of a liquid to gas

- always (+) b/c the process is endothermic

- somewhat temperature dependent.

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vapor pressure:

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pressure of a gas in dynamic equilibrium w/ its liquid.

- depends on the intermolecular forces present in the liquid & the temp.

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dynamic equilibrium

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Front 49

When the temperature of a liquid increases, what happens to the vapor pressure?

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it increases

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boiling pt. of a liquid:

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the temp @ which its vapor pressure = the external pressure

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normal boiling pt. of a liquid:

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the temp. @ which its vapor pressure = 1atm

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critical temperature:

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the temp. above which the liquid cannot exist

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critical pressure:

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the pressure required to bring about a transition to a liquid at a critical temp.

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supercritical fluid:

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when gas and liquid phase commingle

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Sublimation:

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The phase transition from solid to gas

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deposition:

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the phase transition from gas to solid

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Melting pt.:

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molecules have enough thermal energy to overcome the intermolecular forces that hold them @ their stationary pts. & solid turns into liquid.

- process is called melting

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Fusion (melting):

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the phase transition from solid to liquid

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Freezing:

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the phase transition from liquid to solid.

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Heat of fusion:

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- the amount of heat required to melt 1 mole of solid

- (+) because melting is endothermic

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example of heating curve:

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Front 62

Phase diagram:

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a map of the phase of a substance as a function of pressure (y-axis) & temperature (x-axis)

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Regions on a phase diagram:

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(s,l,g)
represents conditions where that particular phase is stable.

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Lines (curves) on the phase diagram:

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represent a set of temperatures and pressures at which the substance is equilibrium between the two phases.

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Triple point:

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represents the unique set of conditions @ which 3 phases are equally stable & in equilibrium

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critical point:

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represents the temperature and pressure above which supercritical fluid exists.

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Water properties:

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- low molar mass (18.02g/mol)

- liquid at room temperature

- high boiling point because of strong hydrogen bonds with other water molecules.

- can dissolve many other polar and ionic compounds.

- is the main solvent within living organisms, and the environment.

- expands upon freezing leading to ice being less dense than liquid water.

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cystalline solids:

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comprising a well-ordered array of atoms or molecules

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amorphous solids:

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having no long-range order

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simple cubic unit cell:

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1 atom per unit cell. (each unit cell actually contains only one-eight of each of the eight atoms at its corners.