Chapter 12 Charges Of Phase

Question 0

What is a closed system

Answer 0

One that matter cannot get into or out of.. But energy can

Question 1

Define equilibrium

Answer 1

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

Question 2

Define a theoretical construct

Answer 2

No system can be completely closed but can come close

Question 3

Define phase

Answer 3

Any part of a system with uniform composition and properties

Question 4

Give an example of a phase

Answer 4

A flash of water with a stopper in it is a liquid vapor closed system. Here two phases are liquid and vapor

Question 5

What can water molecules at the surface gain

Answer 5

Energy and escape the surface (evaporate)

Question 6

What are h2o molecules below the surface held in place by

Answer 6

Surrounding molecules

Question 7

Why do surface molecules evaporate easily

Answer 7

Because they are not held at the surface

Question 8

What will some of the molecules do that escaped?

Answer 8

They will lose energy and return to the surface of the liquid (condense)

Question 9

What happens if temperature remains constant

Answer 9

There will be a point where the amount evaporating will equal amounts condensing. Equilibrium will be established

Question 10

What happens at equilibrium

Answer 10

The relative amounts of liquid and vapor will be constant not necessarily equal

Question 11

Give two equilibrium expressions

Answer 11

Liquid + heat energy -> vapor (evap)
Vapor -> liquid + energy (condensation)
liquid+ heat vapor

Question 12

What is Le Chatlier’s principle

Answer 12

When a system at equilibrium is disturbed by a stress, a new equilibrium point will be established that will minimize the stress
-for Le Chatlier’s, stress is a charge in pressure, temperature or volume of a container

Question 13

What happens when you have more liquid at new equilibrium point

Answer 13

Add energy and reaction is pushed in reverse (right to left so more liquid at new equilibrium point; also less vapor)

Question 14

What happens when pressure increases

Answer 14

Will push reaction equilibrium to the left

Question 15

What happens when pressure decreases

Answer 15

Will push reaction equilibrium to the right

Question 16

What happens when volume of the system increases

Answer 16

Pressure decreases

Question 17

What happens when a volume of the system is decreased

Answer 17

Pressure increases

Question 18

Define EVP

Answer 18

The pressure exerted by a vapor that is at equilibrium with its liquid temperature dependent

Question 19

What happens if the temperature of the liquid is increased

Answer 19

More liquid molecules will gain enough KE to escape from the surface of the liquid

Question 20

If the temperature of the liquid is increased what does it cause the vapor pressure to do

Answer 20

To increase, exerting a higher EVP, a new equilibrium point will be established with more vapor and use less liquid. Therefore EVP changes with temperature

Question 21

Define volatile liquids

Give three examples

Answer 21

Evaporate quickly cause of weak attraction between molecules
Ether, ammonia, perfume

Question 22

Define nonvolatile liquids

Give two examples

Answer 22

Evaporate slowly cause of strong attractions between molecules
Water, oil

Question 23

Define boiling

Answer 23

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

Question 24

When does boiling occur

Answer 24

When EVP equals atmospheric pressure at certain place and time

Question 25

Define boiling point

Answer 25

It is temperature at which EVP of a specific liquid equals atmospheric pressure (which changes..)

Question 26

What happens at low altitudes

Answer 26

Boiling point is low

Question 27

What happens at high altitudes

Answer 27

Boiling point is high

Question 28

What is constant at boiling point? Why?

Answer 28

Temperature is constant at boiling point, continued addition of heat provides energy to evaporate the liquid but temperature will not get higher

Question 29

When will water boil faster but not hotter

Answer 29

Adding salt

Question 30

To keep a liquid boiling what do you do

Answer 30

Continue to add heat

Question 31

Define molar heat of evaporation

Answer 31

Amount of energy needed to vaporize one mole of a liquid at it’s boiling point

Question 32

What kind of attraction do molecules have at high values & low values

Answer 32

Strong attraction ; weak attractions

Question 33

When do freezing and melting occur

Answer 33

At same temperature for specific substances

Question 34

What must a solid gain to become a liquid

Answer 34

Energy

Question 35

What must a liquid lose to become a solid

Answer 35

Energy