C2: Phases and Thermochemistry Flashcards

Class 2

1
Q

describe the phase change from:
solid to gas

A

sublimination

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2
Q

describe the phase change from:
solid to liquid

A

fusion/ melting

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3
Q

describe the phase change from:
liquid to gas

A

vaporization/ boiling/ evaporation

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4
Q

describe the phase change from:
gas to liquid

A

condensation

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5
Q

describe the phase change from:
liquid to solid

A

solidification/ freezing/ crystallization

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6
Q

describe the phase change from:
gas to solid

A

deposition

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7
Q

from solid > liquid > gas…
- heat is (absorbed/ released) ____
- temperature ____
- kinetic energy ____
- entropy ____
- intermolecular forces ____

A
  • absorbed
  • increases
  • increases
  • increases
  • decrease
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8
Q

from gas > liquid > solid …
- heat is (released/ absorbed) ____
- temperature ____
- kinetic energy ____
- entropy ____
- intermolecular forces ____

A
  • released
  • decreases
  • decreases
  • decreases
  • increase
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9
Q

in a phase transition diagram,
what is the heat of transition?
- heat of fusion?
-heat of vaporization?

A

the amount of energy required to to complete a transition
- the amount of heat that must be absorbed to change a solid into a liquid
- the energy absorbed when a liquid changes to a gas

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10
Q

what formula is used when trying to find the amount of heat within a phase transition diagram?
- if change in H and q are positive, heat is ____
- if change in H and q are negative, heat is ____

A

q= n x change in H(phase change)
where q= heat
n= # of moles of substance
- absorbed
- released

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11
Q

what is the formula for heat capacity?

A

q= mc x change in T
where q= heat
m= mass of the sample
c= specific heat of the substance

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12
Q

what is a calorie?

A

the amount of heat required to raise the temperature of 1 gram of water by 1 degree C

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13
Q

the specific heat of a substance depends upon its ____

A

phase (s, l, g)

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14
Q

what is the SI unit for energy?

A

joule

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15
Q

1 cal = ____ J

A

4.2

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16
Q

which 11 elements are gases at standard state conditions?

A

H2, N2, O2, F2, Cl2, He, Ne, Ar, Kr, Xe, Rn

17
Q

which 2 elements are liquid at standard state conditions?

A

Hg and Br2

18
Q

what are the 7 diatomic elements at standard state conditions?
- what is a good mnemonic to remember these?

A

H2, N2, O2, F2, Cl2, Br2, I2
- BrINCl HOF

19
Q

for molecular solids..
- describe their structure
- are they malleable or rigid?
- are they conductors?
- are their BPs and MPs low or high?

A
  • nonmetal atoms connected by covalent bonds, molecules have weak intermolecular forces
  • soft
  • no
  • low
20
Q

for ionic solids..
- describe their structure
- are they malleable or rigid?
- are they conductors?
- are their BPs and MPs low or high?

A
  • metal cations and nonmetal anions from a crystal lattice locked in by electrostatic interaction
  • rigid
  • no
  • high
21
Q

for metallic solids..
- describe their structure
- are they malleable or rigid?
- are they conductors?
- are their BPs and MPs low or high?

A
  • metal atoms form cations with delocalized valence electrons
  • malleable
  • yes
  • medium
22
Q

for covalent networks ..
- describe their structure
- are they malleable or rigid?
- are they conductors?
- are their BPs and MPs low or high?

A
  • carbon or metalloid atoms form an extended network of covalent bonds
  • rigid
  • mostly no
  • very high
23
Q

in a phase transition diagram..
- which is on the x and y axis?
- inclines indicate ___ changes and plateaus indicate ____ changes. can both of these happen at the same time?
- the first incline indicates a ____ state, second a ____ state, and third a ____ state
- the first plateau indicates ____ and the second indicates ____

A
  • x axis= heat (q), y axis= temperature
  • temperature; phase. cannot happen simultaneously
  • solid; liquid; gas
  • fusion; vaporization
24
Q

what is specific heat (c)?
- what does a large c mean?
- small c?

A

the amount of heat required to increase the temperature of 1 gram (or 1 mol) of a substance by by 1 degree C or 1K
- slower to heat or cool
- faster to heat or cool

25
Q

what is heat capacity (C)

A

the amount of heat required to increase any amount of a substance by 1 degree C or 1K

26
Q

in phase change diagrams…
- what goes on the x and y axis?
- what does it look like?
- what is the triple point?
- what is the critical point?
- what is supercritical fluid?

A
  • x axis= temperature, y axis= pressure
  • solid towards top left, then liquid in middle, then gas on bottom center
  • where the 3 phases coexist
  • when the phase ends
  • when you go past the critical point where the phases do not exist
27
Q

what does the phase diagram for water look like?

A

slightly negative slope

28
Q

what happens to waters melting point when external pressure decreases?

A

it increases

29
Q

the temperature of a substance is a measure of its internal ____ and is not changing

A

kinetic energy

30
Q

why does a pot of boiling waters temperature remain constant despite the addition of heat?

A

the heat is used to break hydrogen bonds rather than increase the temperature