ch.11 - liquids, solids & intermolecular...

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CHEMISTRY - CLUTCH

CH.11 - LIQUIDS, SOLIDS & INTERMOLECULAR FORCES

CONCEPT: POLARITY

Molecules that have _______________ sharing of electrons contain a molecular polarity.

• For these molecules, both _________________ and _________________ determine the molecular polarity. POLARITY RULES TO BEING NON-POLAR:

1) If central element has NO lone pair(s): a. Central element must be connected to the ___________ elements.

b. Central element must be ______________ electronegative than the surrounding elements.

PRACTICE 1: Determine if carbon dioxide, CO2, is polar or nonpolar.

2) If central element has lone pair(s): a. Central element must be connected to the ___________ elements. b. Central element must be ______________ electronegative than the surrounding elements. c. Use dipole arrows to point to the ________ electronegative element. These dipole arrows must cancel out. d. Dipole arrows extend _____________________ lone pairs. These lone pair dipole arrows must cancel out.

PRACTICE 2: Determine if xenon tetrafluoride, XeF4, is polar or nonpolar.

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CONCEPT: POLARITY PT.2

Molecules that have unequal sharing of electrons contain a molecular polarity.

• Some molecular shapes are seen as perfect and will always lead to a non-polar molecule overall. POLARITY RULES TO BEING NON-POLAR:

1) A perfect shape will be non-polar as long as: a. The central element is connected to the same elements.

b. The central element is less electronegative than the surrounding elements.

O C O H C N

3 Groups2 Groups F

BF F

SnF F

AX3 - Trigonal Planar AX2E1 - Bent, Angular or V-ShapedAX2 - Linear

4 Groups NH

HHC

Cl

ClClCl H

OH

AX4 - Tetrahedral AX2E2 - Bent, Angular or V-ShapedAX3E1 - Trigonal Pyramidal

5 Groups

Xe FF

AX5 - Trigonal Bipyramidal

ClP

ClCl

Cl Cl

F Cl F

FAX4E1 - Seesaw AX2E3 - Linear

FS FF

F

AX3E2 - T-Shaped

6 Groups ClSCl Cl

Cl ClClXe

H

H

H

HAX6 - Octahedral AX4E2 - Square Planar

F

SFF F

F

AX5E1 - Square Pyramidal

EXAMPLE 1: Determine if silicon tetrachloride, SiCl4, is polar or nonpolar. EXAMPLE 2: Determine if phosphorus trihydride, PH3, is polar or nonpolar.

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PRACTICE: POLARITY PRACTICE 1: Determine if the following compound is polar or nonpolar.

a. SiBr42- PRACTICE 2: Determine if the following compound is polar or nonpolar.

a. H2S PRACTICE 3: Determine if the following compound is polar or nonpolar.

a. PCl2F3 PRACTICE 4: Determine if the following compound is polar or nonpolar.

a. IF2 –

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CONCEPT: INTERMOLECULAR FORCES

When looking at a molecular substance such as H2O you will discover two types of electrostatic forces at work:

______________ forces exist within a molecule and influences the _____________ properties of the substance.

______________ forces exist between molecules and influence the _____________ properties of the substance.

___________________ is the force that exists between an ion and a polar compound. (Strongest)

Ex:

___________________ is the force that exists when H is directly connected F, O, N. (2nd Strongest)

Ex:

____________________ is the force that exists when two polar covalent compounds interact. (3rd Strongest)

Ex:

____________________is the force that exists when a nonpolar covalent compound interacts with a polar

covalent compound. (4th Strongest)

Ex:

____________________ is the force that exists when two nonpolar covalent compounds interact. (Weakest)

Ex:

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PRACTICE: INTERMOLECULAR FORCES

EXAMPLE: Based on the given compounds, answer each of the following questions:

a. CH3CH3 b. KBr c. C6H5OH d. CaS e. Ne

a) Which compound will have the lowest boiling point?

b) Which compound will have the highest surface tension.

c) Which compound will have the highest vapor pressure.

PRACTICE 1: The predominant intermolecular force in C6H5NH2 is:

a. London Dispersion b. Hydrogen Bonding c. Ion-Dipole d. Dipole-Dipole e. Dipole-induced Dipole

PRACTICE 2: The predominant intermolecular force in HBr is:


PRACTICE 3: The predominant intermolecular force in ZnBr2 with H2O is:


PRACTICE 4: The predominant intermolecular force in Ne with H2O is:


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CONCEPT: SOLUBILITY

According to the theory of __________ dissolves ____________ compounds with the same intermolecular

force or polarity will dissolve into each other.

EXAMPLE: Identify the intermolecular forces present in both the solute and the solvent, and predict whether a solution will

form between the two.

a. CCl4 and P4

b. CH3OH and C6H6

c. C6H5CH2NH2 and HF

d. IF4 – and NH3

PRACTICE: Which of the following statements is/are true?

a. Methane will dissolve completely in acetone, CH3COCH3.

b. Hydrofluoric acid (HF) will form a heterogeneous mixture with tetrachloride, CCl4.

c. Pentane will form a homogeneous mixture with CBr4.

d. Methanethiol (CH3SH) is miscible in fluoromethane (CH3F).

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CONCEPT: PHASE DIAGRAMS

Under appropriate conditions of pressure and temperature, most substances can exist in 3 states of matter: ___________,

_______________ and ________________.

Microscopic Explanation for the Behavior of Gases, Liquids and Solids

Gas Liquid Solid

Assumes the

___________ and ___________

of its container.

Assumes the __________ of the

portion of its container it occupies,

but not the __________ .

Maintains a fixed

___________ and ___________

___________________ compressible

Viscosity Viscosity Viscosity

____________________ Viscous

___________________ compressible ___________________ compressible

____________________ Viscous ____________________ Viscous

Now, a convenient way to show the effect that temperature and pressure has on a pure substance in a closed system

without any air is to use a phase diagram.

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PRACTICE: PHASE DIAGRAMS

a) At what temperature can we no longer tell the difference between the liquid and the gas? _____________

b) Which point represents an equilibrium between the solid, liquid and gas phase? _____________

c) Which line segment represents an equilibrium between fusion and freezing? _____________

d) Which line segment represents an equilibrium between sublimation and deposition? _____________

e) Which line segment represents an equilibrium between condensation and vaporization? _____________

f) What is the normal freezing point of this unknown substance? _____________

g) What is the normal boiling point of this unknown substance? _____________

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CONCEPT: HEATING & COOLING CURVES

In heating and cooling curves we have the representation of the amount of heat absorbed or released during phase changes.

Time

Tem

pera

ture

(oC

)

Heating Curve

Time

Tem

pera

ture

(oC

)

Cooling Curve

Specific Heat of Ice 2.09 Jg ⋅ oC

ΔHFusion 334 Jg

Specific Heat of Water 4.184 Jg ⋅ oC

ΔHVaporization 2260 Jg

Specific Heat of Steam 1.84 Jg ⋅ oC

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PRACTICE: HEATING & COOLING CURVE CALCULATIONS 1

EXAMPLE: How much energy (kJ) is required to convert a 76.4 g acetone (molar mass = 58.08 g/mol) as a liquid at -30 oC

to a solid at -115.0 oC?

Specific Heat of Solid 1.65 Jg ⋅ oC

ΔHFusion 7.27 kJmol

Specific Heat of Liquid 2.16 Jg ⋅ oC

Specific Heat of Gas 1.29 Jg ⋅ oC

TMelting − 95.0 oC

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PRACTICE: HEATING & COOLING CURVE CALCULATIONS 2

PRACTICE: If 53.2kJ of heat are added to a 15.5g ice cube at - 5.00 oC, what will be the resulting state and temperature of the substance?

Specific Heat of Ice 2.09 Jg ⋅ oC

ΔHFusion 334 Jg

Specific Heat of Water 4.184 Jg ⋅ oC

ΔHVaporization 2260 Jg

Specific Heat of Steam 1.84 Jg ⋅ oC

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CONCEPT: SOLID STATE STRUCTURAL FEATURES Solids are grouped into two broad categories based on the organization of their particles and shapes:

_______________________ solids.

• Tend to have well-established shapes because their particles occur in an organized pattern.

_______________________ solids.

• Tend to have poor-established shapes because their particles lack an overall organized pattern.

When examining the particles within a crystal you may observe them tightly packed in an organized pattern.

• The ____________________ point represents the area within the crystal that has identical surroundings all around.

• The ____________________ represents the smallest portion of the crystal that, if reproduced in all three directions, would give the crystal.

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CONCEPT: THE SIMPLE CUBIC UNIT CELL

There are ______ crystal systems and ______ types of unit cells that naturally occur, but we will only focus on those that follow cubic lattice system.

The simple cubic unit cell is made of a cube with one atom at each corner.

• The edge length is twice the radius of the atoms so ____________________.

• Then unit cell does not contain 8 atoms, but actually only ___________ atom because

each corner atom is shared by eight other unit cells.

• The packing efficiency is equal to ___________________________.

• The coordination number is equal to _______________________.

Unit Cell Diagram

Lattice Diagram

Space Filling Unit Cell Diagram

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CONCEPT: THE BODY-CENTERED CUBIC UNIT CELL

The body-centered cubic unit cell is made of a cube with one atom at each corner and one atom of the same kind in the center of the cube.

• The edge length is equal to _________________________ .



Unit Cell Diagram

Lattice Diagram


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CONCEPT: THE FACE-CENTERED CUBIC UNIT CELL

The face-centered cubic unit cell is made of a cube with one atom at each corner and one atom of the same kind in the center of each cube face.

• The edge length is equal to _________________________.



Unit Cell Diagram

Lattice Diagram


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PRACTICE: THE CUBIC UNIT CELL (CALCULATIONS 1) EXAMPLE 1: An element crystallizes in a face-centered cubic lattice and it possesses a density of 2.03 g/cm3. The edge of its unit cell is 4.11 x 10-8 cm. How many atoms are in each unit cell?

EXAMPLE 2: Based on Example 1, what is the volume of a unit cell?

EXAMPLE 3: Based on Example 1, what is the mass a unit cell?

EXAMPLE 4: Based on Example 1, calculate the approximate atomic mass of the element.

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PRACTICE: THE CUBIC UNIT CELL (CALCULATIONS 2) EXAMPLE 1: KF has the same type of crystal structure as NaCl. The unit cell of KF has an edge length of 5.39 angstroms. Find the density of KF.

EXAMPLE 2: Which one of the following is not a general property of ionic solids?

a) Hard and brittle b) Good electrical conductors in the solid state c) Relatively high melting points d) Strongest interparticle attractions are electrostatic e) Positions of ions define the unit cell (lattice)

EXAMPLE 3: Lead crystallizes in a face-centered cubic structure. What is the edge length of the unit cell if the atomic radius of gold is 180 pm?

a) 185 pm

b) 288 pm

c) 360 pm

d) 509 pm

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PRACTICE: THE CUBIC UNIT CELL (CALCULATIONS 3)

EXAMPLE 1: Chromium metal crystallizes in a body-centered cubic structure with a unit cell edge length of 2.89 angstroms. The radius of a chromium atom is __________ angstroms.

a) 0.91

b) 3.90

c) 2.25

d) 1.25

e) 1.57

EXAMPLE 2: A solid has a very high melting point, great hardness, and poor electrical conduction. This is a(n) __________ solid. Example: Rubies

a) covalent network

b) metallic and covalent network

c) ionic

d) metallic

e) molecular

EXAMPLE 3: Determine the radius of an Ag atom (in pm) if the density of silver is 10.5 g/cm3. Silver crystallizes in a face

centered cubic structure with an edge length of 4r 2 .

a) 144 pm

b) 186 pm

c) 83 pm

d) 303 pm

e) 127 pm

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CONCEPT: CLASIUS-CLAPEYRON EQUATION

By using the Clasius-Clapeyron equation a quantitative relationship between _____________________ and _____________________ can be established.

ln P2P1= −

ΔHvap

R1T2−1T1

#

$%

&

'(

`

EXAMPLE : The heat of vaporization (∆Hvap) of water is 40.3 kJ/mol at its normal boiling point at 100oC. What is the vapor pressure (in mmHg) of water at 60oC?

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ch.11 - liquids, solids & intermolecular...

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