Change in States of Matter &Energy

Question 1

Phase

Answer 1

part of a system that has uniform composition and properties (solid, liquid, gas)

Question 2

Condensation

Answer 2

gas changes to a liquid

Question 3

Vapor

Answer 3

a gas in contact with its liquid or solid phase

Question 4

Equilibrium

Answer 4

a condition by which two opposing charges occur at equal rates in a closed system

Question 5

(in a closed system) Equilibrium occurs when..

Answer 5

the rate of condensation is the same as the rate of evaporation

Question 6

Equilibrium of Vapor Pressure is affected by:

Answer 6

1. Concentration
2. Temperature
3. Pressure

Question 7

Equilibrium Vapor Pressure of a Liquid:

Answer 7

the pressure exerted by a vapor in equilibrium with its liquid at a given temp

Question 8

Vapor Pressure is measured using…

Answer 8

a mercury manometer

Question 9

Because the forces of attraction are diff for diff liquids:

Answer 9

the quilibrium vapor pressure is specific for each liquid at a given temp

Question 10

Volatile Liquids:

Answer 10

liquids that evaporate easily due to very weak forces of attraction

Question 11

Nonvolatile Liquids:

Answer 11

liquids that do not evaporate easily - strong forces of attraction

Question 12

Energy is always involved when:

Answer 12

physical or chemical change occurs

Question 13

Energy can be in forms of:

Answer 13

heat and ligt

Question 14

Law of Conservation of Energy:

Answer 14

energy can be absorbed or released in a change, but never destroyed or created

Question 15

Vaporization:

Answer 15

the process by which a liquid changes to a gas

Question 16

Two Types of Vaporization:

Answer 16

Evaporation and Boiling

Question 17

Evaporation:

Answer 17

at the liquids surface

Question 18

Boiling:

Answer 18

the change of a liquid to a gas within the liquid and at its surface

Question 19

Boiling Point:

Answer 19

the temp at which the equilibrium vapor pressure of the liquid = the atmospheric pressure (surroundings)

Question 20

Lower atmospheric pressure =

Answer 20

lower boiling point

Question 21

Normal Boiling Point (n.b.p):

Answer 21

the boiling point of a liquid at standard atmospheric pressure (1atm, 760torr, or 101.3 kPa)

Question 22

n.b.p of water:

Answer 22

100 C

Question 23

n.b.p. for ethyl alcohol

Answer 23

100 C

Question 24

Boiling & Evaporation are _________- physical change processes

Answer 24

endothermic

Question 25

Endothermic:

Answer 25

energy must be added in order for the change to take place

Question 26

Liquid + energy ->

Answer 26

gas

Question 27

Condensation Is a _______ physical change process

Answer 27

exothermic

Question 28

Exothermic:

Answer 28

energy must be removed in order for the change to take place

Question 29

gas -> liquid + ______

Answer 29

energy

Question 30

Heat of Vaporization:

Answer 30

the amnt of heat energy needed to boil 1 gram of liquid at the substance's boiling point

Question 31

Heat of Vaporization for Water:

Answer 31

2260 J/g

Question 32

Heat of vaporization formula:

Answer 32

q = mHvap q= energy (J) m= mass Hvap= heat of vaporization 8

Question 33

Freezing:

Answer 33

physical change from a liquid to a solid

Question 34

Energy:

Answer 34

Freezing involves loss of energy

Question 35

The normal freezing point (n.f.p):

Answer 35

the temp at which the solid and liquid are in equilibrium at standard atmospheric pressure

Question 36

At equilibrium, melting and freezing occur...

Answer 36

at equal rates

Question 37

Melting is an ________ physical change process

Answer 37

endothermic

Question 38

Freezing is an _______ physical change

Answer 38

Exothermic

Question 39

solid + ____ -> liquid

Answer 39

energy

Question 40

Heat of fusion:

Answer 40

the amnt of heat energy required to melt 1 gram of solid at the substance's melting point

Question 41

Heat of Fusion for water:

Answer 41

334 J/g

Question 42

Heat of Fusion formula :

Answer 42

q = mHfus

Question 43

In low temp and low pressure conditions a liquid...

Answer 43

cannot exist

Question 44

In low temp and low pressure conditions a solid....

Answer 44

exists at equilibrium with it vapor ---instead of its liquid

Question 45

SUblimation:

Answer 45

the change of state from a solid directly to a gas

Question 46

Deposition:

Answer 46

(the reverse process) the change of state from a gas directly to a solid

Question 47

Triple Point:

Answer 47

point at which all three states of matter are in equilibrium - exist at same time

Question 48

Critical point:

Answer 48

the critical pressure & temp of a substance

Question 49

Critical Temp:

Answer 49

The temp above which the substance cannot exist as a liquid

Question 50

Critical pressure:

Answer 50

the lowest pressure at which the substance, at critical temp, can exist as a liquid