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CHEM > Thermodynamics > Flashcards

Thermodynamics Flashcards

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1
Q

What is THERMODYNAMICS

A

Study of energy changes in relation with physical or chemical processes

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2
Q

2 main terms in THERMODYNAMICS

A

System & Surroundings

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3
Q

A system can either be….

A

a chemical reaction or physical process

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4
Q

Intensive vs Extensive Property

A

I: does not depend on amount of substance
E: depends on amount of substance

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5
Q

What is Energy?

A

Capacity to do work or transfer heat

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6
Q

1 cal is = to?

A

4.184 J

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7
Q

3 types of Systems

A

Open - exchange of heat and matter thru system
Closed - exchange of only heat thru system
Isolated - does not allow exchange of anything

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8
Q

What is Internal Energy

A
  • sum of energies of all the particles in a system
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9
Q

Formula for Internal Energy (3)

A

E or U = PE + KE
ΔE = E final- E initial
ΔE = q + w

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10
Q

Potential Energy VS Kinetic Energy

A

PE: from interactions between particles
KE: types of motion

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11
Q

3 types of KE

A
  1. Rotational
  2. Translational
  3. Vibrational
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12
Q

Endothermic vs Exothermic

A

Endo = + value / gaining of heat
Exo = - value / releasing of heat

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13
Q

What do the positive and negative values of q and w meaning?

A

q + = system gained heat
q - = system lost heat

w + = work done ON the system
w - = work done BY the system

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14
Q

What is PV work?

Formula

A

Work done by an EXPANDING gas

w = -PΔV

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15
Q

How many Joules is 1 L-atm?

A

101.3 J

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16
Q

1st Law of Thermodynamics (2)

A

Law of Conservation of energy

“The total energy in the universe is constant”

+ Change in ENTHALPY

17
Q

ΔE universe is = to?

A

ΔE system + ΔE surroundings = 0

18
Q

What is ENTHALPY?

unit?

formulas (2)?

A

Total heat content of a system

ΔH

ΔH = ΔE system + PV
ΔH = H products - H reactants

19
Q

Is HEAT an extensive or intensive property

A

extensive

20
Q

Where is heat in the equation of:

  • Endothermic Rxns
  • Exothermic Rxns
A

ENDO = reactants
EXO = products

21
Q

Identify if EXO or ENDO:

S -> L -> G
G -> L -> S

+ which has highest and lowest energy state?

A
  1. ENDO
  2. EXO

GAS = highest energy state kasi requires the highest amount of heat to retain that phase

22
Q

MANIPULATING THERMOCHEMICAL EQUATIONS

If:
1. Equation is reversed, what happens to ΔH?
2. Equation is multiplied by n, what happens to ΔH?

A
  1. ΔH changes signs (either becomes negative or positive)
  2. ΔH also gets multiplied by n
23
Q

Who authorized the LAW OF HEAT SUMMATION?

A

Germain Henri Hess

24
Q

What does the LAW OF HEAT SUMMATION state?

A

the enthalpy (heat) change of an overall process is the sum of all heat changes of its individual steps

25
Q

2nd Law of Thermodynamics (2)

A

Law of Entropy

“In any spontaneous change, there is always an increase in entropy (disorder)”

+ Change in ENTROPY

26
Q

Entropy Formula

A

ΔS = S final - S initial

27
Q

MEANING:

+ΔS
-ΔS
ΔS = 0

A

spontaneous
non-spontaneous
at equilibrium

28
Q

Gibbs Free Energy Formula

A

ΔG = ΔH - TΔS

29
Q

MEANING:

-ΔG
+ΔG
ΔG = 0
ΔG°

A

Exergonic (loss of free energy) + spontaneous
Endergonic (gain of free energy) + nonspontaneous
Equilibrium
STANDARD free energy change (1 atm and 25 °C)

30
Q

What does GIBBS FREE ENERGY state? (2)

A
  • determines whether a reaction can happen spontaneously
  • a state function that depends on the initial and final equilibrium states, not the path taken to get there
31
Q

Is T in GIBBS FREE ENERGY formula in Celsius or Kelvin

A

Kelvin

32
Q

What types of phase changes are considered endothermic and what are considered exothermic?

A

ENDO = melting (fus), vaporization (vap), sublimation (sub)

EXO = freezing (freez), condensation (con), deposition (dep)

33
Q

KE and PE behaviour in CC and HC

A

CC Horizontal line (Phase Change)
- KE constant
- PE decreases

CC diagonal line (no phase change)
- KE decreases
- PE constant

HC is opposite of KE so increase

34
Q

HEAT CAPACITY vs SPECIFIC HEAT CAPACITY

A

HC (Extensive) (C) - q/delta T

SHC (Intensive) (Cp) - C/g

35
Q

FORMULA FOR:

  • no phase change
  • w phase change
A

q = m Cp ΔT
q = m ΔH

wherein ΔH = J/g

CHEM (27 decks)

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