Thermochemistry

Question 1

Isolated System

Answer 1

Exchange neither matter nor energy with the environment.

Question 2

Closed System

Answer 2

Can exchange energy but not matter with the environment.

Question 3

Open System

Answer 3

Can exchange both energy and matter with the environment.

Question 4

Isothermal Process

Answer 4

Constant temperature

Question 5

Adiabatic Process

Answer 5

Exchange no heat with the environment

Question 6

Isobaric Process

Answer 6

Constant pressure

Question 7

Isovolumetric

Answer 7

Constant volume

Question 8

State Functions

Answer 8

Describe the physical properties of an equilibrium state. Are pathway independent. Pressure, density, temp, volume, enthalpy, internal energy, Gibbs free energy, and entropy.

Question 9

Standard State Conditions

Answer 9

298 K, 1 atm, 1 M

Standard temp and pressure is 0 degrees Celsius, and 1 atm.

Question 10

Fusion

Answer 10

Solid –> Liquid

Question 11

Freezing

Answer 11

Liquid –> Solid

Question 12

Vaporization

Answer 12

Liquid –> Gas

Question 13

Sublimation

Answer 13

Solid –> Gas

Question 14

Deposition

Answer 14

Gas –> Solid

Question 15

Triple Point

Answer 15

Point in phase diagram where all three phases exist

Question 16

Supercritical Fluid

Answer 16

Density of gas = density of liquid, no distinction between those two phases.

Question 17

Temperature (T)

Answer 17

Scaled measure of average kinetic energy of a substance

Question 17

Temperature (T)

Answer 17

Scaled measure of average kinetic energy of a substance

Question 18

Celsius vs Fahrenheit

Answer 18

0 degrees C = 32 degrees F (Freezing point of H2O)
25 degrees C = 75 degrees F (Room temp)
37 degrees C = 98.6 degrees F (Body temp)
F = (9/5 C) + 32

Question 19

Heat (q)

Answer 19

The transfer of energy that results from differences of temperature. Hot transfers to cold.

Question 20

Enthalpy (H)

Answer 20

A measure of the potential energy of a system found in intermolecular attractions and chemical bonds.

Question 21

Is Solid –> Liquid –> Gas endothermic or exothermic?

Answer 21

Endothermic since gases have more heat energy than liquids and liquids have more heat energy than solids.

Question 22

Hess’s Law

Answer 22

Enthalpy changes are additive.

Question 23

Delta Hrxn from heat of formations

Answer 23

Delta Hrxn = Delta Hproducts - Delta Hreactants

Question 24

Delta Hrxn from bond dissociation energies

Answer 24

Delta Hrxn = Delta Hreactants - Delta Hproducts

Question 25

Entropy (S)

Answer 25

A measure of the degree to which energy has been spread throughout a system or between a system and its surroundings. Delta S = qrev / T

Question 26

Standard entropy of reaction

Answer 26

Delta Srxn = Delta Sfproducts - Delta Sfreactants

Question 27

Gibbs Free Energy (G)

Answer 27

Derived from enthalpy and entropy.

Delta G = Delta H - T Delta S

Question 28

Standard Gibbs free energy of reaction

Answer 28

Delta Grxn = Delta Gfproducts - Delta Gfreactants

Question 29

Gibbs free energy from equilibrium constant Keq

Answer 29

Delta Grxn = -RT ln (Keq)

Question 30

Gibbs free energy from reaction quotient Q

Answer 30

Delta Grxn = RT ln (Q/Keq)

Delta Grxn = Delta Grxn + RT ln (Q)

Question 31

When Delta G < 0, the reaction is…

Answer 31

Spontaneous

Question 32

When Delta G = 0, the reaction is…

Answer 32

at equilibrium

Question 33

When delta G > 0, the reaction is

Answer 33

non-spontaneous

Question 34

When Delta H and Delta S are positive, the reaction is…

Answer 34

spontaneous at high temps

Question 35

When Delta H is positive and Delta S is negative, the reaction is…

Answer 35

non-spontaneous at all temps

Question 36

When Delta H is negative and Delta S is positive, the reaction is

Answer 36

spontaneous at all temps

Question 37

When delta H and delta S are negative, the reaction is

Answer 37

spontaneous at low temps