Chapter 8 & 10 Flashcards Preview

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Flashcards in Chapter 8 & 10 Deck (41):
1

Evaporation

-liquid --> gas
-heat/ energy is required to overcome strong forces in liquid (therefore endothermic)

2

heat of vaporization/ enthalpy of vaporization

energy required to vaporize 1 mole of liquid at 1 atm of pressure

3

heat vaporization for water

2260 joules per gram

4

condensation

gas --> liquid

5

equilibrium vapour pressure

pressure of vapour present at equilibrium

6

sublimes

solid --> gas

7

heat curve

plot of temperature versus time for a process where energy is added at a constant rate

8

heating curve for water

-energy is added
-vibrations of water molecules increase as temperature rises
-molecules break loose from position
-goes from solid to liquid (plateau at 0 degrees) (all energy is used to disrupt the ice structure by breaking hydrogen bonds) (melting point)
-becomes completely liquid
-boiling point (100 degrees)
-energy added to vaporize liquid, temperature remains constant (100 degrees)
-liquid completely vapour
-temperature rises again

9

melting point

the temperature where a solid and liquid have the same vapour pressure where the total pressure is 1 atm

10

boiling point

-temperature at which the vapour pressure of liquid is exactly 1 atm
-100 degrees

11

phase diagram

represents the phases of a substance as a function of temperature and pressure

12

triple point

-all three states of water are present
-solid and liquid water have identical vapour pressures

13

critical temperature

the temperature above which vapour cannot be liquidated no matter what pressure is applied

14

critical pressure

the pressure required to product liquefaction at the critical temperature

15

critical point

-critical temperature + critical pressure
-water = 374 degree at 218 atm
-for water it is liquid/vapour line

16

phase diagram for water

-melting point of ice decreases at external pressure increases (this happened because density of ice is less than that of liquid water at melting point)
-the solid/liquid boundary has a negative slope
-if pressure is increased and temperature is constant the ice will melt (increased pressure causes matter to reduce its volume) (ice has a larger volume than the same mass of liquid water)

17

phase diagram for water in ice skating

pressure from skate causes it to melt

18

phase diagram for water in lakes and rivers and stuff...

lower density of ice means that ice formed on rivers will float, giving a layer of insulation below

19

phase diagram for water in boiling water

-liquid boils where vapour pressure equals external pressure (depends on external pressure)
-at different elevations, water boils at different temperatures

20

phase diagram for carbon dioxide

-solid/liquid line is positive (solid carbon dioxide is more dense than liquid carbon dioxide)
-triple point: 5.1 atm, -56.6 degrees
-critical point: 72.8 atm and 31 degrees
-sublimes: -78 degrees

21

calorimeter

device used to determine the heat associated with a chemical reaction

22

calorimetry

-science of measuring heat
-based on observing the temperature change when a body absorbs or discharges energy as heat
-the amount of energy required depends on amount of substance present

23

molar heat capacity

-heat capacity per mole
-J/Celsius or J/K * mol

24

endothermic reaction

-absorbs heat from surroundings
-vaporization and fusion are some examples
decreased for surroundings (T is negative)(negative quantity)
-system has positive quantity
-enthalpy change is always POSITIVE

25

exothermic reaction

-releases heat to surroundings
-heat released results in a temperature increase for surrounds (T is positive)(positive quantity)
-heat released by system must have reverse sign (negative quanitity)
-enthanpy change is always NEGATIVE

26

heat of fusion

amount of heat that must be abosrbed to melt a speciic quantity of solid

27

heat content/ enthalpy

-stored energy
-the amount of heat transferred in a process depends on the difference in the energy stored in each substance

28

enthalpy change

the heat change that occurs at constant pressure

29

qp

-amount of heat transferred
-it depends on mass (m), heat (s), and temperature change (T)

30

specific heat of a substance

-it reflects its ability to absorb heat energy
-defined as the amount of heat needed to raise the temperature of one gram by one degree

31

specific heat of water

4.18 J/gC

32

temperature change (T)

equal to difference between final temperature and initial temperature

33

s

specific heat

34

normal boiling point

temperature at which the vapour pressure of the liquid is exactly 1 atm

35

melting

solid to liquid

36

evaporation

liquid to gas

37

freezing

liquid to solid

38

condensation (dew)

gas to liquid

39

sublimation

solid to gas

40

deposition

gas to solid

41

desntiy of liquid in dry ice

-there is a positive slope
-therefore the solid is denser than the liquid