Chapter 12

Question 0

Surface tension

Answer 0

The forces that tends to pull a liquid surface inward, creating the smallest possible surface area.

Question 1

Properties of liquids. (3)

Answer 1

Density: more dense than gases; could be more/less dense than solids
Compressibility: not compressible; already tightly packed
Diffusion: slow because particles are closer; random motion; attractive forces; faster temp = faster diffusion because of average kinetic energy

Question 2

Cohesion

Adhesion

Answer 2

Attractive forces between like forces

Attractive forces between different particles

Question 3

Capillary action

Answer 3

A liquid is drawn into a thin space due to adhesive property.

Question 4

Vaporization
Vapor
Gas

Answer 4

Process of turing into a gas.
Gas phase of a substance normally (at room temperature) a solid/ liquid.
Normally a gas a room temperature.

Question 5

Liquid to gas
Evaporation
Boiling

Answer 5

Process by which particles escape from the surface of a nonboiling liquid and enter the gas state. Slower; occurs at the surface; occurs at any temperature.
Conversion of s liquid to a vapor within the liquid as well as at its surface. Of course when the equilibrium spot pressure of the liquid equals the atmospheric pressure. Faster; occurs from within; occurs at some specific temperature.

Both forms of vaporization

Question 6

Evaporation (5)

Answer 6

Liquid particles must gain energy.
Only the ones on the surface go.
Cooling process.
If energy is removes, particles slow down and solidify.
Occurs b/c of different kinetic energies: higher=faster; higher than average can overcome intermolecular forces and escape

Question 7

Melting point

Freezing point

Answer 7

Temperature at which solid turns to liquid.
Temperature at which liquid turns to solid.

Both happening at the same time.
Both: same temperature.

Question 8

Crystalline solids

Answer 8

Repeating geometric pattern to molecules.

Question 9

Amorphous solids (4)

Answer 9

No particular pattern to molecules.

• melting range: candle wax, silly putty, window glass, plastic
• “pseudo solids”: “super cooled liquids”
• high density
• low diffusion

Question 10

Ionic crystals (5)

Answer 10

• consist of positive and negative particles.
• elements form groups 1 and 2 with groups 6 and 7.
• strong bonds: high melting points; good insulators of electricity; hard and brittle.

Question 11

Covalent network crystals (4)

Answer 11

• single atoms of the same element which covalently bond to identical atoms nearby: Diamond
• very hard and very brittle
• very high melting points (strong bonds)
• nonconductors or semiconductors

Question 12

Metallic Crystals (7)

Answer 12

• Electrons overlapping with 8-12 other metal atoms. “Sea of electrons” “delocalized electrons”
• high conductivity (of electricity)
• malleable: can be dented/flattened
• ductile: can be drawn into him wire

Question 13

Colvalent molecular crystals (6)

Answer 13

• molecules held together by intermolecular forces.
• fairly weak attractions
• low melting point
• low boiling point
• fairly soft: not hard/brittle
• good insulators

Question 14

Equilibrium

Answer 14

(Dynamic condition)2 opposing processes occur at the same rate.
Rate of evaporation=rate of condensation
Liquid+energy yields (both ways) gas

Question 15

Lechatelier’s Principal

Answer 15

If a system at equilibrium is subjected to a stress the equilibrium will shift to release the stress.
Liquid+energy yields (both ways) vapor

Question 16

Equilibrium vapor pressure

Answer 16

Pressure in a gas due to the vapors of s substance in equilibrium with its liquid at that temperature.

Question 17

Volatile liquids

Answer 17

Evaporate easily: high vapor pressure; low/weak attractions between particles

Question 18

Boiling

Normal boiling point

Answer 18

What occurs when the vapor pressure of the liquid equals the atmospheric pressure above it.
Temperature at which equilibrium of the liquid equals standard temperature.

Question 19

Normal freezing point

Answer 19

Temperature at which a solid and a liquid are in equilibrium.

Question 20

Molar heat of fusion

Answer 20

Amount of heat needed to melt 1 mole of a substance at its melting temperature.

Question 21

Molar heat of fusion and vaporization of water.

Answer 21

Hf: 6.009 kJ/mol
Hv: 40.79 kJ/mol

Question 22

Molar heat of vaporization

Answer 22

Amount of energy needed to vaporize 1 mile of a substance at its boiling temperature.

Question 23

Sublimation

Answer 23

Solid changes directly to a gas.

Dry ice co2 and I2

Question 24

Deposition

Answer 24

Gas to solid.

Question 25

Triple point

Answer 25

Temperature and pressure combo at which solid/liquid/gas are in equilibrium. (.006 atm and .01 degrees Celsius)

Question 26

Critical temperature

Answer 26

Max. Temperature a liquid will exist at any pressure. | For H2O 647 K=374 degrees Celsius

Question 27

Critical pressure

Answer 27

Pressure needed to liquify a substance at critical temperature. For H2O 218 atm Lowest pressure a substance can exist as a liquid at the critical temperature.

Question 28

Water is most sense at 4 degrees Celsius.

Answer 28

Hydrogen bonding: causes particles to move apart creating less density.

Question 29

Liquid

Answer 29

Matter that has a definite volume and takes the shape of its container.

Question 30

Meniscus

Answer 30

Concave liquid surface

Question 31

Vaporization

Answer 31

Process by which liquid or solid changes to a gas.

Question 32

Freezing or solidification

Answer 32

Physical change of a liquid to a solid by removal of heat.

Question 33

Properties of solids (7)

Answer 33

- stronger intermolecular forces (packed closer) - vibrate around each other, fixed in place - definite shape and volume - definite melting point (exc. amorphous) - high density, particles are packed closer - incompressible: pores filled with air, intense pressure=pores compress not the solid - low diffusion, strong attraction

Question 34

Crystalline solids Crystal Amorphous solid

Answer 34

Consist of crystals Substance in which the particles are arranged in an orderly,geometric, repeating pattern Particles are arranged randomly (Greek: without shape)

Question 35

Melting Melting point Supercooled liquids

Answer 35

Physical change of a solid to a liquid by the addition of heat. Temperature at which a solid becomes a liquid. Substance that retain certain liquid properties even at temperature at which they appear to be solid

Question 36

Crystal structure

Answer 36

The total 3-D arrangement of particles of a crystal.

Question 37

Unit cell

Answer 37

The smallest portion of a crystal lattice that shows the 3-D pattern of the entire lattice.

Question 38

Phase.

Answer 38

Any pet if a system that has uniform composition and properties.

Question 39

Condensation

Answer 39

Process by which a gas changes to a liquid.

Question 40

Boiling point

Answer 40

Of a liquid: temperature at which the equilibrium vapor pressure of the liquid equals the atmospheric pressure.

Question 41

Normal freezing point

Answer 41

Temperature at which the solid and liquid are in equilibrium at 1 atm.

Question 42

Phase diagram

Answer 42

Graph of pressure versus temperature that shows the conditions under which the phases of a substance exist.

Question 43

Critical point

Answer 43

Indicates the critical temperature and critical pressure.

Question 44

Water

Answer 44

- temp (kinetic energy) increases, hydrogen bonding difficult. 4-8 molecules per liquid H2O - empty spaces in ice b/w molecules= low density