Liquids and Solids Exam 1

Question 1

Surface tension

Answer 1

(greek letter looking like y); resistance for the surface of the liquid to an external force because of the attractive forces between molecules. Decreases with increasing T (higher T = higher KE); decreases with lower attractive forces

Question 2

Cohesive forces

Answer 2

forces between like molecules (ex: droplets on waxed car(stays on top as a bead))

Question 3

Adhesive forces

Answer 3

forces between unlike molecules (droplet spreads out over surface)

Question 4

capillary action

Answer 4

ex of adhesive force; used in blood tests and in paper chromatography to draw liquid up a tube.

Question 5

viscosity

Answer 5

resistance to flow of a liquid and is a result of cohesive forces. As T increases, Viscosity decreases (higher KE)

Question 6

Vapor Pressure

Answer 6

partial pressure of a gas located directly above a liquid.

Energy of evaporation is measured as delta Hvap, enthalpy of vaporization. No T change in this process; it is endothermic (heat enters system)

Question 7

Boiling point

Answer 7

When the temperature increases along with the vapor pressure, and the vapor pressure equals the atmospheric pressure, the liquid will begin to boil.

Question 8

Critical point

Answer 8

when the density of the liquid equals that of the gas and the surface tension equals 0, then the substance has reached its critical temperature and critical pressure.

Question 9

network covalent solids

Answer 9

solid composed of covalent bonds. ex: graphite, diamond, nanotubes; mostly nonconductors

Question 10

metallic

Answer 10

(cations, delocalized e-); range of mp; malleable; insoluble; ductile; good conductors

Question 11

ionic

Answer 11

(cations, anions);(electrostatics); regularity; high mp; at least slightly soluble; aqueous conductor; solid nonconductor; hard

Question 12

nonpolar molecular

Answer 12

(atoms or nonpolar molecules); (dispersion forces); soft, low mp, some sublime, some are soluble

Question 13

polar molecular

Answer 13

dipole-dipole; low mp; some are soluble

Question 14

h-bonded molecular

Answer 14

(h-bonds); low mp; some are soluble

Question 15

Delta H fusion

Answer 15

enthalpy of melting

Question 16

sublimation

Answer 16

solid to gas

Question 17

deposition

Answer 17

gas to solid

Question 18

solid to liquid

Answer 18

melting (+) (endothermic)

Question 19

liquid to solid

Answer 19

freezing (-) (exothermic)

Question 20

vaporization

Answer 20

liquid to gas (+) (endothermic)

Question 21

condensation

Answer 21

gas to liquid (-) (exothermic)

Question 22

supercooled liquid

Answer 22

a cooled liquid that has no place for crystals to form

Question 23

superheated liquid

Answer 23

a heated liquid that has no place for bubbles to form

Question 24

isobar

Answer 24

line at constant pressure

Question 25

isotherm

Answer 25

line at constant temperature

Question 26

intermolecular forces

Answer 26

when two molecules come into proximity of each other, they exert intermolecular forces of each other. (ex: h-bonding, dipole-dipole, london dispersion)

Question 27

intramolecular forces

Answer 27

forces within bonds (ex: ionic, covalent, metallic)

Question 28

Van der Waal

Answer 28

forces that are both london and dipole

Question 29

instantaneous dipoles

Answer 29

temporary dipole created in the molecule with a partially negative and partially positive charge. the dipole is drawn (e- go to one side)

Question 30

polarizability

Answer 30

ability for an atom or molecule to form instantaneous dipoles, and it increases as volume occupied by electrons (i.e. size) increases.

Question 31

H-bonding

Answer 31

occurs when an H atom is directly bonded to an electronegative element (N O F) forming a very strong dipole. (occurs between H of one molecule and electronegative of other)

Question 32

If the force is high...

Answer 32

viscosity is high, surface tension is high, bp is high, vp is low