Lecture 17

Question 1

The amount of heat needed to melt one mole of a solid is called

Answer 1

the heat of fusion (ΔHfus)

Question 2

Crystallization amount of energy process

Answer 2

ΔHcrystal = -ΔHfus

Question 3

Vaporization amount of energy compared to fusion

Answer 3

ΔHvap > ΔHfus

Question 4

Heat of fusion of water plus melting point

Answer 4

H20-melting point:( 0C ), heat of fusion: 6.02 kJ/Mol

Question 5

Heat of fusion of isopropyl alcohol

Answer 5

C3H7OH- melting point: ( -89.5 ), heat of fusion: 5.37

Question 6

heat of fusion of acetone

Answer 6

C3H6O -melting point (-94.8 ), heat of fusion: 5.69

Question 7

Heat of fusion of Diethyl ether

Answer 7

C3H10O melting point: (- 116.9 ), heat of fusion: 7.27

Question 8

Stronger intermolecular forces =

Answer 8

higher boiling points, melting points, and heat of vaporization; they also have lower vapor pressures.

Question 9

Miscible

Answer 9

Liquids that do not separate, no matter what the proportions.

Question 10

Dispersion forces

Answer 10

London forces or instantaneous dipoles.
Caused by distortions in the electron cloud of one molecule inducing distortion in the electron cloud on another.

The temporary dipoles lead to attractions between molecules

Question 11

Strength of dispersion force compared to size of molecule

Answer 11

Strength of the dispersion force gets larger with larger molecules

Question 12

size of molecule (Mm vs. boiling point)

Answer 12

smaller the gas, the lower the boiling point

Question 13

Polar molecules

Answer 13

oppositely charged atoms (h20)

Question 14

Non polar molecules

Answer 14

Equally charged, generally dissolved in non polar. CO2.

Question 15

covalent bond

Answer 15

2 non metals bonded, electron sharing

Question 16

Ionic

Answer 16

Electron transfer. Metal + non metal. Cations plus anions. Metal + polyatomic compound.

Question 17

Dipole to dipole attraction

Answer 17

Polar molecules have permanent dipole (a+ end and a- end and + end always attaches to - end of another)

Question 18

Polarity and dipole to dipole attraction

Answer 18

The bigger the dipole size, the higher the boiling point. Polar molecules

Question 19

Immiscible liquids

Answer 19

DO NOT mix because they are more attracted to their own kind than the other (oil and water example-polar and non polar)

Question 20

Hydrogen bonding (HF, OH, NH groups) bond strength and other features

Answer 20

STRONG bonds. High boiling, melting, and solubility in water. NOT a chemical bond.

Question 21

In order of strongest to weakest bonds (forces)

Answer 21

Hydrogen bonds> Dipole to Dipole force > Dispersion force (all have dispersion force)

Question 22

Molecular solids (crystalline solids)

Answer 22

Composite units are molecules. Low melting

Question 23

Ionic solids

Answer 23

Composite units are formula units (cations and anions). High melting. (NACL)

Question 24

Atomic solids

Answer 24

Composite units are atoms. Variable melting.

Question 25

Metallic bonds

Answer 25

varied melting and boiling points.

Question 26

What does luster, malleability, ductility, electrical, and thermal conductivity depend on what?

Answer 26

Mobility of electrons in the solid.