Chapter 7- Thermodynamics

Question 1

Three types of systems

Answer 1

Isolated- no matter or energy exchanged

Closed- exchanges only energy

Open- exhanges both matter and energy

Question 2

Isothermal vs Adiabatic vs Isobaric vs Isovolumetric

Answer 2

Isothermal- constant temperature
Adiabatic- exchange no heat with environment
Isobaric- constant pressure
Isovolumetric (isochoric) constant volume

Question 3

State functions and examples

Answer 3

Describe physical properties of an equilibrium state, pathway dependent

Pressure, Density, Temperature, Volume, Enthalpy (H), internal energy (U), Gibbs free energy, Entropy (S)

Question 4

Standard conditions

When do you use it?

Answer 4

Temperature: 298 K
Pressure: 1 atm
Concentration: 1M

When measuring Enthalpy Entropy Gibbs free energy (prime)

Question 5

STP

When do you use it?

Answer 5

Standard temperature and pressure

T- 0 C, 273 K

P- 1 atm

Ideal gas problems

Question 6

Triple point

Answer 6

All three phases exist in equilibrium

Question 7

Critical point

Answer 7

When liquid and gas phases are indistinguishable

Question 8

Sublimation

Answer 8

Solid to gas

Question 9

Deposition

Answer 9

Gas to solid

Question 10

Condensation

Answer 10

Gas to liquid

Question 11

Vaporization

Answer 11

Liquid to gas

Question 12

Temperature vs heat

Answer 12

Temperature: average kinetic energy of a substance

Heat: transfer of energy results in difference in temperature

Question 13

Enthalpy

Answer 13

Measure of potential energy of a system found in intermolecular attractions and chemical bonds

Question 14

Hess’s Law

Answer 14

The total change in potential energy in system is equal to the changes of potential energies of the individual steps of the process.

Question 15

q=mc🔺t

mass in grams/moles?

Answer 15

Used in between phase changes

Mass in grams

Question 16

q=ml

Mass in grams or moles?

Answer 16

Used when temperature is constant

Mass in mol

Question 17

q=ml units

Answer 17

M= mass in mol

L= latent heat kj/mol (heat of fusion, heat of vaporization)

Question 18

q=mc🔺t units

Answer 18

m= mass in grams
c= specific heat J/g x K
T=K

Question 19

Specific heat of water

Answer 19

1 cal/g x K

Question 20

How to calculate the enthalpy change of a reaction?

Answer 20

🔺Hrxn = H products - H reactions

Question 21

Endothermic vs Exothermic 🔺H

Answer 21

endothermic positive delta H

exothermic negative delta H

Question 22

Bond breaking absorbs or releases energy

Answer 22

Absorbs (endothermic)

Question 23

Bond making absorbs or releases energy

Answer 23

Releases energy (exothermic)

Question 24

Second law of thermodynamics

Answer 24

Energy spontaneously disperses from being localized to becoming spread out if it is not hindered from doing so. 

Question 25

Entropy

Answer 25

Measure of spontaneous dispersal of energy at a specific temperature.

Question 26

Calculating change in entropy

Answer 26

S=Qrev/T
🔺S change in entropy
Qrev= heat gained or lost in a reversible process
T temperature Kelvin

Question 27

Unit for entropy

Answer 27

J/mol/K

Question 28

increasing/decreasing entropy and energy distribution

Answer 28

Entropy increases: Energy distributed into a system

Entropy decreased: Energy distributed out of a system

Question 29

Rank the phases of matter from lowest to greatest entropies

Answer 29

Solid > Liquid > Gas

Question 30

Exergonic rxn vs endergonic

Answer 30

Exergonic system releases energy spontaneous

Endergonic system absorbs energy nonspontaneous

Question 31

+/- 🔺G

Answer 31

Negative spon

Positive nonspon

Question 32

If delta g is = 0

What does that mean for H and S?

Answer 32

🔺H= T🔺S