Chapter 12: Changes Of Phase

Question 0

Describe a closed system

Answer 0

One that matter can’t enter or escape but NRG can; but theoretically no system can be completely closed

Question 1

Define equilibrium

Answer 1

The dynamic condition in which 2 opposing changes occur at equal rates in the same closed system

Question 2

Why is the closed system a theoretical construct?

Answer 2

Bc no system can be completely closed

Question 3

Defoe a phase and give and example

Answer 3

Any part of a system with uniform composition and properties

Ex: flask of eyed with a stopper in it is a liquid/vapor closed system. Liquid and vapor being the phases

Question 4

What can wayer molecules at the surface do ?

Answer 4

Gain NRG and escape the surface(evaporate)

Question 5

Why can water molecules at the surface evaporate easier?

Answer 5

These molecules at the surface are not held in place by surrounding molecules

Question 6

When will an equilibrium be established?

Answer 6

If temperature remains constant there is a point where the amount of evaporation will equal the amount of condensation

Question 7

At equilibrium what happens tithe relative amounts of liquid and vapor?

Answer 7

Remain constant but not necessarily equal

Question 8

What is the equilibrium expression

Answer 8

Liquid + heat vapor

Question 9

What happens when a system at equilibrium experiences stress? Le Chaltiers theory of stress.

Answer 9

A new equilibrium will be established that will minimize stress

Question 10

State the equation for the effects of temperature

Answer 10

Liquid + NRG vapor

Question 11

What is the result when NRG is adde to a system at equilibrium and vice versa

Answer 11

The rxn is pushed forward
The rxn is pushed into reverse
Both forming new equilibrium a

Question 12

State the equation for the effects of p

Answer 12

Liq + NRG vapor

Question 13

Which state of matter responds from a change in p

Answer 13

Gases

Question 14

Explain how an increase in P will effect the system and decrease

Answer 14

Pushes equilibrium to the left and decreasing to the right

Question 15

What other stress has the same effect as V

Answer 15

P

Question 16

What happens when a volume of gas decreases and vice versa

Answer 16

P increases

Decreases ( think Boyles law)

Question 17

Define EVP

Answer 17

The P exerted by a vapor that is at equil. With it’s liquid

Question 18

When will wayer molecules gain enough KE to move to the surface

Answer 18

When T increases

Question 19

What causes P of vapor to increase?

Answer 19

Increase in temperature

Question 20

Define volatile liquid and give an example

Answer 20

Evap. quickly Bc weak attraction between molecules

Ammonia gas

Question 21

Define nonvolatile liquids

Answer 21

Don’t evaporate fast Bc strong attraction between molecules

Water oil

Question 22

Define booling point

Answer 22

The change of a liq to a vapor within the liquid as well as the surface

Question 23

When does booling occur

Answer 23

when EVP = ATM P at a certain place and time

Question 24

How does boiling point vary with P

Answer 24

Directly

Question 25

How does altitude affect booling point

Answer 25

At high P booling point is slightly lower and vice versa

Question 26

What happens to the temp at booling point

Answer 26

Constant

Question 27

At what T is boiling point at SP

Answer 27

100C

Question 28

How can you boil water faster

Answer 28

Above SP

Question 29

Define molar heat of vaporization

Answer 29

Amount if NRG needed to vaporize 1 mil of a liquid at it’s boiling point

Question 30

When is there a strong attractive force between molecules

Answer 30

When the molar heat of vaporization is high

Question 31

Compare freezing and melting points for specific substances

Answer 31

Occur at the same temperature

Question 32

Wrote te equation of freezing and melting

Answer 32

Solid + NRG liq

Question 33

How will a solid become a liq and vice versa

Answer 33

Gaining or losing NRG

Question 34

Define te molar heat f fusion

Answer 34

Amount of heat to melt 1 mil of a solid @ it’s melting point

Question 35

What does the molar heat of fusion depend on

Answer 35

The attractive forces between molecules in the substance

Question 36

Define sublimation and deposition and give examples of each

Answer 36

@ very low Temp liquids can’t exist and so a vapor will exist at equilibrium with its solid
Sub. Dry ice snow moth balls
Dep. snow

Question 37

What is the phase change diagram

Answer 37

a P vs V graph showing the conditions at which the phases of a diff. Substance exist

Question 38

Define triple point

Answer 38

T and P at which all 3 phases co- exist

Question 39

Define critical T

Answer 39

Above this temp substance cannot exist as a liq. Regaurdless of P

Question 40

Define critical P

Answer 40

Lowest P at which a substance can exist as a liq. While at its critic T

Question 41

Describe a water molecule and it’s bond angle

Answer 41

Polar covalent bonded molecules formed by 105 Degree bond angles

Question 42

Define hydrogen bond a

Answer 42

Weak bonds between H and a very electronegative element (N F O) bond is fluid and changeable

Question 43

Described H bonds in liquid form

Answer 43

Fluid an transient

Question 44

Describe the H bonds in ice

Answer 44

Rigid unchangimg framework that traps pockets of air

Question 45

When does te maximum density of water occur

Answer 45

4C

Question 46

Name four properties of water

Answer 46

Transparent
Odorless
Tasteless
Colorless