Intermolecular forces: Solids, Liquids, and Solutions

Question 1

Polarizability

What is Polarizability?

Answer 1

• Ability to induce another nonpolar molecule to have a momentary dipole between instantaneuous and indused dipole
• Happens with Covalent Compounds

Question 2

IMF Trends

LDF Trends

Answer 2

• Increased = Increased size
• Increased = Increased polarizability
• Increased = Greater Charge Separation

Question 3

Dipole-Dipole forces

What are they?

Answer 3

• Polar molecules with positive “end” and negative “end” which have a permanent dipole which attracts other dipoles when closer
• Stronger than LDF

Question 4

Important Note!

What to do with LDF on Test

Answer 4

• Write full form: London Dispersion Forces

Question 5

Hydrogen bonds

Conditions

Answer 5

1. H has to be attached to F,O,N
2. Other end is also F,O,N with/without H

Question 6

Hydrogen bonds

What are they?

Answer 6

• Strong and special d-d
• Have to write both d-d + h-b
• bet H proton and negative side of F,O,N

Question 7

Surface Tension

Definition

Answer 7

• Amount of energy required to stretch
• Increased surface of liquid by 1 unit area
• Higher IMFs = Higher ST

Question 8

Surface Tension

Adhesion

Answer 8

IMFs between unlike molecules

Question 9

Surface Tension

Cohesion

Answer 9

IMFs between like molecules

Question 10

Viscocity

Definition

Answer 10

• Measure of a fluid’s resistance to flow
• Increased T = Decreased V
• Increased V = Increased IMFs
• Tangling ==> Increased V

Question 11

H2O

Properties

Answer 11

• Excellent Solvent
• High Specific heat
• Ice Density is less than Water because struct for spread out

Question 12

Liquid-Vapor Equilibrium

Vapor Pressure

Answer 12

• Partial pressure of liquids once equilbrium is established between gases and liquids
• Book Definition: Gaseous molecules pressure form evap. liquid

Question 13

Liquid-Vapor Equilibrium

Dynamic Equilbrium

Answer 13

• Rate of forward process(l–>g) = Rate of backward process(g–>l)
• Constant Pressure

Question 14

Liquid-Vapor Equilibrium

When is Boiling Point?

Answer 14

• When Vapor Pressure is equal to External pressure

Question 15

Phase Changes

Critical Point

Answer 15

• Temperature that gas cant become a liquid no matter the pressure

Question 16

IMF Trends

How are physical characteristics affected by IMFs?(only writing abt. high)

BP, VP, Viscocity, ST, Cohesive Forces

Answer 16

• Higher BP
• Lower VP
• Higher viscocity
• Higher ST
• High Cohesive Forces

Question 17

Hydrogen Bonding

Salicylic Acid

Answer 17

• H-Bonding within molecule

Question 18

Chromatography Lab

Rf

Answer 18

solute Distance/ Solvent Distance

Question 19

VP Curves

Equation

Answer 19

• ln(Pvap1, T1/Pvap2, T2)=(∆Hvap/R)((1/T2)-(1/T1))

Question 20

Alloys

Definition

Answer 20

• Solid Soln consisting of 2+ metals or metals with 1 + nm

Question 21

Covalent Network Solids

Definition

Answer 21

• Network of covalently-bonded atoms into 2D and 3D network, holding it firmly together

Question 22

Covalent Network Solids

Allotropes

Answer 22

• Elements exist in 2 diff formes in same physical state
• Ex) diamond and graphite for carbon

Question 23

Semiconductors

Definitions

Answer 23

• Elements that are normally not conductors but are at high Temperatures or when coombined with other elements

Question 24

Semicoductors

N-type

Answer 24

• Have an extra electron from bonding which can be used to create a voltage
• Donor Impurities

Question 25

Semiconductors

P-type

Answer 25

• Have 1 less electron which creates “positive holes” that constatnly shift and allow current to flow through holes
• Acceptor Impurities

Question 26

Physical Properties of Solns

Solvents

Answer 26

• determine soln’s state of matter
• usually majority component

Question 27

Physical Properties of Solns

Solutes

Answer 27

• Substance dissolbed/dispersed in the solvent

Question 28

Physical Properties of Solns

Solution Concentration

Answer 28

• Amnt of solute/ amount of solvent/soln

Question 29

Physical Properties of Solns

Molality(m)

Answer 29

• moles of solute/ kg of solvent
• varies with mass of solvent and is independent of temperature

Question 30

Physical Properties of Solns

Enthalpy of Soln

Answer 30

• Combination of Heat required breaking IMFs of solute and solvent plus the heat released for letting them mix

Question 31

Physical Property of Solutions

Non-Ideal Solutions

Answer 31

• Not additive solutions(adding two solutions doesn’t result in a solutions with both that is not equal than combined amount: Ex) 50mL +50mL≠100mL)
• Happens due to unequal IMFS
• example of Ideal Mixture = Benzene and Methylbenzene

Question 32

Physical Properties of Solutions

How Heat of Solution impacts ideality

Answer 32

• If = 0, Ideal
• If < 0, stronger solute-solvent forces; exothermic
• If > 0, weaker solute-solvent forces; endothermic

Question 33

Formation of a Saturated Solution

What is a Saturated Solution

Answer 33

• Maximum amount of solid or gas allowed in a liquid with constant Temperature

Question 34

Formation of Saturated Solution

How temperature affects saturation

Answer 34

• Increased ==> Increased in solids
• Opposite in gases

Question 35

Formation of Saturated Solution

Henry’s Law

Answer 35

• Increased Solubility = Increased Pressure
• s = P * k

Question 36

Formation of Saturated Solution

K in Henry’s Law

Answer 36

• Units: mg[gas]/100g[H2O]/atm

Question 37

Colligative vs Noncolligative Properties

What are Colligative Properties?

Answer 37

• Physical Properties that depends only on concentration of solute particles, not their identity
• Decreased solvent vapor pressure, Freezing Point Depression, Boiling Point Elevation

Question 38

Colligative vs Noncolligative Properties

Examples of Noncolligative Properties

Answer 38

• Color, odor, etc.

Question 39

Volatile Solvents

What if solute is non-volatile?

Answer 39

• Lower solvent volatility because less on surface
• Raoult’s Law: Vapor Psolv = Xsolv ·P°solv

Question 40

Volatile Solvents

What if solute is volatile?

Answer 40

• Have to consider both Vapor Pressures
• Pressure[Tot] = P[solvent A] + P[solvent B]
  = (XsolvA · P°solvA) + (XsolvB · P°solvB)

Question 41

Fractional Distillation

How does Fractional Distillation work?

Answer 41

1. Boil 2 liquids
2. Lower Boiling Point will boil out
3. Rise to the condenser
4. distillate
   * Example: Water(50mL) + Ethanol(50mL) = mixture (< 100mL)
   
   • Distillation = 50 mL each again