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DDEL > Thermodynamics > Flashcards

Thermodynamics Flashcards

1
Q

IDEAL GASES

A

PV = nRT

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2
Q

Gas constant (R)

A

8.3145 LkPa/Kmol

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3
Q

What does a high temp correlate to for pressure?

A

A higher temperature would increase the kinetic energy of the atoms.

Therefore the atoms would move faster and collide more (INCREASING PRESSURE)

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4
Q

What does a low temperature correlate to for pressure?

A

A low temperature would mean that the atoms have a low kinetic energy and therefore MOVE SLOWER.

Less Collisions = Lower pressure

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5
Q

1 ATM

A

101325 Pa
or
101.325 kPa

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6
Q

STP

A

Standard Temperature & Pressure.
* 0°C or 273 k
* 1 ATM

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7
Q

ΔU

A
  • ΔU = q + w
  • ΔU = q +pΔV
  • ΔU = C x ΔT
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8
Q

How would ΔU be demonstrated if the surroundings gain 10.80kJ ?

A

ΔU = - 10.8 kJ

negative value

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9
Q

How would ΔU be demonstrated if the system gains 10.80kJ ?

A

ΔU = 10.8kJ

positive value

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10
Q

First law of thermodynamics

A

ΔU = Q - W

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11
Q

Precision

A

The consistency of results with each other

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12
Q

Accuracy

A

The consistency of results with the true value

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13
Q

In regard to entropy, how does it determine the direction of a reaction?

A

A reaction will always proceed in the direction of increasing disorder .

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14
Q

TRUE OR FALSE

A reaction proceeds in the direction of increased orderliness

A

FALSE

A reaction always proceeds in the direction of increased disorder.

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15
Q

Define…

Entropy

A

The degree of measure of disorder in a system.

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16
Q

TRUE OR FALSE

Generally, in high temperatures there is a higher level of disorder

A

TRUE

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17
Q

Second law of thermodynamics

A

The change in entropy of a system must be greater than 0 for a spontaneous change to occur.

  • ΔS_tot = ΔS_sys + ΔS_sur < 0: non-spontaneous
  • ΔS_tot = ΔS_sys + ΔS_sur > 0 : spontaneous
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18
Q

TRUE OR FALSE

During a spontaneous change in an isolated system, the entropy decreases.

A

FALSE

For isolated systems, the entropy always increases during a spontaneous change. ΔS_tot > 0

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19
Q

Change in entropy [ΔS]

A
  • ΔS = q_rev / T
  • ΔS = ΔH / T
20
Q

TRUE OR FALSE

There is NO DISORDER at 0 kelvin

A

TRUE

21
Q

Third law of thermodynamics

A

There is no entropy at absolute zero.

22
Q

Formula

Gibbs free energy

A
  • G = H - TS
  • ΔG = ΔH - TΔS
23
Q

Criterion of spontaneity

A

ΔS
* ΔS > 0 : Spontaneous
* ΔS < 0 Non-spontaneous

ΔG
* ΔG < 0 : Spontaneous
* ΔG > 0 : Non-spontaneous

24
Q

Coupled reactions

A

Reactions that are energetically unfavourable can be ‘coupled’ with favourable reactions.

This can be achieved when the overall change in standard gibbs free energy is negative (therefore spontaneous/favourable)

25
Q

Δr_G°

A

Δr_G° = -RT lnK

R (universal constant) = 8.31 J/Kmol

26
Q

TRUE OR FALSE

At equilibrium ΔrG = 0

A

TRUE

27
Q

Δr_G

A

Δr_G = Δr_G° + RT lnK

28
Q

Equilibrium constant [K]

A

K = ( C ^c ) ( D ^d )/ (A ^a) ( B ^b)

29
Q

Molar gibbs energy

A

Gm = G/n

  • n = number of moles
  • G = Gibbs free energy
30
Q

Formulas…

Enthalpy

A
  • H = U + PV
  • H =
31
Q

Triple point

A

The point in which the substance exists in all three phases at the same time in equilibrium.

32
Q

Critical point

A

The temperature and pressure point on a phase diagram where the LIQUID and GASEOUS phases of a substance merge together into one substance called the supercritical fluid

33
Q

Gibbs phase rule

A

The number of intensive variables that must be defined to determine the state of a system.

F = C - P + 2

34
Q

Intensive variable

A

A variable that is NOT dependent on the quantity of the system (e.g. water)

E.g. : Pressure, Density, Temperature

35
Q

Extensive variable

A

A variable that is dependent on the quantity of the system

E.g. : Volume, Mass, number of moles

36
Q

TRUE OR FALSE

Determining a state requires all the variables of a system

A

TRUE

37
Q

Gibbs phase rule formula

A

F = C - P +2

  • F = # of intensive variables
  • C = # of components
  • P = # of phases
38
Q

Clausius-Clapeyron equation

A

Δln p / ΔT = Δ_evap_ H / RT^2

39
Q

chemical potential

A

μ_A = μ°_A + RT lnX_A

40
Q

How can you determine the gibbs free energy of a reaction?

A

G = (n_A)(μ_A ) + (n_B)(μ_B)

41
Q

TRUE OR FALSE

Raising the temperature on an exothermic reaction will shift the equilibrium to the right

A

FALSE

There will be more heat on the product side so the equilibrium will counter by shifting to the reactants / left

42
Q

Van’t Hoffs equation

Normal

A

ln(K2/K1) = ΔH/R (T2-T1/T2T1)

43
Q

Van’t Hoff equation

In respect to ΔH

A

ΔH = R ln(K2/K1) (t2t1/t2-t1)

44
Q

Clausius-clapeyron equation

A

Ln(P2/P1)= ΔH/R (T2-T1/ T2T1)
* P = vapor pressure

45
Q

TRUE OR FALSE

Increasing the temp for an Endothermic reaction shifts to the right

A

TRUE

46
Q

TRUE OR FALSE

The reaction shifting to the reactants means the reactants decrease

A

FALSE

The reactants will increase if the reaction shifts towards them.

47
Q

Le chatelier’s principle

A

Endothermic reaction
* Increase temp = more products
* Decrease temp = more reactants

Exothermic reaction
* Increase temp = more reactants
* Decrease temp = more products

DDEL (4 decks)

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