Thermodynamics (Dr.Miles TAMU)

Question 1

Isolated systems

Answer 1

No exchange of energy or matter (thermos)

Question 2

Closed system

Answer 2

Only energy allowed to exchange (unopened soda)
- Matter inside system will always stay
- If System is heated then gaining energy, if cooled then losing energy

Question 3

Open system

Answer 3

Both energy and matter allowed to exchange. (humans, cell)
- all living things are open systems

Question 4

How to change internal energy for a closed system

Answer 4

Heat or work

Question 5

If any energy is added or lost it comes from and goes to

Answer 5

The surroundings and the amount of energy in the universe is constant (1st law of thermodynamics)

Question 6

+q vs -q

Answer 6

positive means heat is being added to the system from surroundings and negative means system is losing energy to the surroundings

Question 7

+w vs -w

Answer 7

positive work is done by the system(loses energy) on the surrounding and negative work means that the surrounding is doing work on the system (gains energy)

Question 8

State functions

Answer 8

Energy = state of system and the pathway the system took took t reach the state
- E is independent of the path
- Always represented by a capital number

Question 9

Non state functions

Answer 9

Dependent n the pathway used to go from initial to final state
- Will always be represented by lower case letter

Question 10

Enthalpy

Answer 10

defined as: H = E + PV
- q put in doesn’t remain as heat but can be work passed into the surroundings
- ΔH = ΔE + ΔPV

Question 11

If ΔH is more than 0(positive)

Answer 11

then heat energy is being put into the system. Such a condition is termed endothermic

Question 12

If (Δ)H is less than 0(negative)

Answer 12

then heat energy is given off by the system. Such a condition is termed exothermic

Question 13

entropy

Answer 13

Increase in Randomness and disorder

Question 14

2nd Law of Thermodynamic

Answer 14

All spontaneous processes proceed from an ordered to disordered state. All spontaneous processes increase the entropy of the universe. All spontaneous reactions will proceed till equilibrium is reached.

Question 15

The sign of (Δ)G determines _____and the magnitude of ΔG indicates_____

Answer 15

Direction, how far the process proceeds to equilibrium

Question 16

Equilibrium

Answer 16

Is a state of minimum potential energy
- any process with a nonzero ΔG will spontaneously proceed to equilibrium

Question 17

if the process A to B is associated with free energy, then how will the reaction proceed in ΔG is positive? Negative?

Answer 17

• If ΔG is positive then the process will proceed in the reverse direction. i.e. B to A
• If ΔG is negative then the process will proceed as written. i.e. A to B

Question 18

All living things are entropy ____ at the expense of universe and/or surroundings. Living organism are always battling ____

Answer 18

catalyst(speed up), entropy

Question 19

Gibbs free energy equation

Answer 19

ΔG=ΔH-TΔS

Question 20

When the reaction has a negative ΔH and a Positive ΔS, what is the reaction type? is it endergonic or exergonic at T? is it always spontaneous?

Answer 20

G<0
~ This is an exothermic reaction because G<0
~ process is exergonic at all temperatures
~ spontaneous all temperatures
~ and is at equilibrium when G=0

Question 21

When the reaction has a negative ΔH and a negative ΔS, what is the reaction type? is it endergonic or exergonic at T? is it always spontaneous? what are the opposed and driven

Answer 21

~ This is an exothermic reaction
~ when T>H/S its endergonic
~ when T<H/S its exergonic
~ Spontaneous as some temperatures
~ Entropically opposed, enthalpically driven

Question 22

When the reaction has a positive ΔH and a positive ΔS, what is the reaction type? is it endergonic or exergonic at T? is it always spontaneous? What are the opposed and driven

Answer 22

~ This is an endothermic reaction
~ when T<H/S is it Endergonic
~ when T>H/S it is exergonic
~ Spontaneous at some temps
~ Entropically driven, enthalpically opposed

Question 23

When the reaction has a positive ΔH and a negative ΔS, what is the reaction type? is it endergonic or exergonic at T? is it always spontaneous

Answer 23

G>0
~ The reactions is endothermic because G>0
~ process is endergonic is at all temperatures
~ nonspontaneous at all temperatures
~ is at equilibrium when G=0

Question 24

R gas constant =

Answer 24

8.3145 J/mol*K

Question 25

equilibrium constant formula given ΔG0

Answer 25

ΔG=-RTln(Keq)