Thermodynamics

Question 1

What is THERMODYNAMICS

Answer 1

Study of energy changes in relation with physical or chemical processes

Question 2

2 main terms in THERMODYNAMICS

Answer 2

System & Surroundings

Question 3

A system can either be….

Answer 3

a chemical reaction or physical process

Question 4

Intensive vs Extensive Property

Answer 4

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

Question 5

What is Energy?

Answer 5

Capacity to do work or transfer heat

Question 6

1 cal is = to?

Answer 6

4.184 J

Question 7

3 types of Systems

Answer 7

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

Question 8

What is Internal Energy

Answer 8

• sum of energies of all the particles in a system

Question 9

Formula for Internal Energy (3)

Answer 9

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

Question 10

Potential Energy VS Kinetic Energy

Answer 10

PE: from interactions between particles
KE: types of motion

Question 11

3 types of KE

Answer 11

1. Rotational
2. Translational
3. Vibrational

Question 12

Endothermic vs Exothermic

Answer 12

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

Question 13

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

Answer 13

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

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

Question 14

What is PV work?

Formula

Answer 14

Work done by an EXPANDING gas

w = -PΔV

Question 15

How many Joules is 1 L-atm?

Answer 15

101.3 J

Question 16

1st Law of Thermodynamics (2)

Answer 16

Law of Conservation of energy

“The total energy in the universe is constant”

+ Change in ENTHALPY

Question 17

ΔE universe is = to?

Answer 17

ΔE system + ΔE surroundings = 0

Question 18

What is ENTHALPY?

unit?

formulas (2)?

Answer 18

Total heat content of a system

ΔH

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

Question 19

Is HEAT an extensive or intensive property

Answer 19

extensive

Question 20

Where is heat in the equation of:

• Endothermic Rxns
• Exothermic Rxns

Answer 20

ENDO = reactants
EXO = products

Question 21

Identify if EXO or ENDO:

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

+ which has highest and lowest energy state?

Answer 21

1. ENDO
2. EXO

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

Question 22

MANIPULATING THERMOCHEMICAL EQUATIONS

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

Answer 22

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

Question 23

Who authorized the LAW OF HEAT SUMMATION?

Answer 23

Germain Henri Hess

Question 24

What does the LAW OF HEAT SUMMATION state?

Answer 24

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

Question 25

2nd Law of Thermodynamics (2)

Answer 25

Law of Entropy

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

+ Change in ENTROPY

Question 26

Entropy Formula

Answer 26

ΔS = S final - S initial

Question 27

MEANING:

+ΔS
-ΔS
ΔS = 0

Answer 27

spontaneous
non-spontaneous
at equilibrium

Question 28

Gibbs Free Energy Formula

Answer 28

ΔG = ΔH - TΔS

Question 29

MEANING:

+ΔG
-ΔG
ΔG = 0
ΔG°

Answer 29

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

Question 30

What does GIBBS FREE ENERGY state? (2)

Answer 30

• 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

Question 31

Is T in GIBBS FREE ENERGY formula in Celsius or Kelvin

Answer 31

Kelvin

Question 32

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

Answer 32

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

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