Thermochemistry

Question 1

What are isolated systems?

Answer 1

they exchange neither matter nor energy with the environment.

Question 2

What are closed systems?

Answer 2

They exchange energy, but not matter with the environment.

Question 3

What are open systems?

Answer 3

they exchange both energy and matter with the environment.

Question 4

What are Isothermal processes?

Answer 4

They are processes that occur at a constant temperature

Question 5

What are adiabatic processes?

Answer 5

exchange no heat with the environment.

Question 6

What are Isobaric processes?

Answer 6

occur at a constant

Question 7

What are isovolumetric (isochoric) processes?

Answer 7

occur at a constant volume

Question 8

What are state functions?

Answer 8

describe the physical properties of an equilibrium state; they are a pathway independent and include pressure, density, temperature, volume, enthalpy, internal energy, Gibbs free energy, and entropy.

Question 9

What are standard conditions?

Answer 9

defined as 298K, 1 atm, and 11 M concentrations. Used for kinetics, equilibrium, and thermodynamics. Do not confuse with (STP) standard temperature and pressure for gas laws.

Question 10

What is the standard state of an element?

Answer 10

it is the most prevalent form under standard conditions; standard enthalpy, standard entropy, and standard free energy

Question 11

What is fusion (melting) and freezing (crystallization or solidification)?

Answer 11

A phase change that occurs at the boundary between the solid and the liquid phases.

Question 12

What is vaporization (boiling or evaporation)?

Answer 12

occurs at the boundary between the liquid and the gas phases

Question 13

What is sublimation and deposition?

Answer 13

occurs at the boundary between the solid and gas phases

Question 14

What is the critical point?

Answer 14

a temp past this, the liquid and gas phases are indistinguishable.

Question 15

What is the triple point?

Answer 15

at this point all three phases of matter exist in equilibrium

Question 16

What is a phase diagram?

Answer 16

fro a system graphs the phases and phase equilibria as a function of temperature and pressure.

Question 17

What is temperature?

Answer 17

scaled measure of the average kinetic energy of a substance.

Question 18

What is heat?

Answer 18

The transfer of energy that results form difference of temperature between two substances.

Question 19

What is Enthalpy?

Answer 19

it is the measure of the potential energy of a system found in the intermolecular attractions and chemical bonds

Question 20

What is Hess’s law?

Answer 20

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

Question 21

How can enthalpy be calculated?

Answer 21

using heat formations, heats of combustion, or bond association.

Question 22

What is entropy?

Answer 22

while often thought of as disorder, is a measure of the degree to which energy has been spread throughout a system or between a system and its surroundings. Entropy is a ratio of heat transferred per mole per unit kelvin. Entropy is maximized at equilibrium.

Question 23

What is Gibbs free energy?

Answer 23

it is derived from both enthalpy and entropy values for a given system. The change in Gibbs free energy determines whether a process is spontaneous or not.

Question 24

What is Gibbs free energy dependent on?

Answer 24

temperature; temp dependent processes, change between spontaneous and non-spontaneous, depending on the temperature.

Question 25

First law of thermodynamics equation

Answer 25

ΔU= Q-W . U is the change in internal energy, Q is heat added, and W is work done by system.

Question 26

Heat transfer (no change) eq

Answer 26

q = mcΔT m is mass, c is specific heat, and T is change in temp. when thinking of heat think which one is receiving heat and losing heat.

Question 27

heat transfer (during phase change)

Answer 27

q=mL . m is mass L is latent heat, a general term for the enthalpy of a isothermal process .

Question 28

Generalized enthalpy of reaction

Answer 28

ΔHrxn = H products - H reactants

Question 29

standard enthalpy of a reaction

Answer 29

ΔH'rxn = ΣΔH'f products - ΣΔH'f, reactants

Question 30

Bond enthalpy

Answer 30

ΔH'rxn = ΣΔH bonds broken- ΣΔH bonds formed

Question 31

Entropy

Answer 31

ΔS = Qrev/T . Qrev is the heat that is gained or lost in a reversible process

Question 32

Second law of thermodynamics

Answer 32

ΔS universe = ΔSsystem + ΔSsurroundings >0

Question 33

Gibbs free energy

Answer 33

ΔG=ΔH- TΔS

Question 34

Standard Gibbs free energy

Answer 34

ΔG'rxn =ΣΔG'f,products - ΣΔG'f,reactants

Question 35

Standard Gibbs free energy from equilibrium constant

Answer 35

ΔG'rxn = -RTln Keq

Question 36

Gibbs free energy from reaction quotient

Answer 36

ΔGrxn= ΔG'rxn +RT ln Q= RT ln Q/Keq

Question 37

Temp and internal energy are..?

Answer 37

directly proportional .

Question 38

PV=

Answer 38

nRT

Question 39

How can energy be supplied to a non-spontaneous reaction?

Answer 39

by coupling non-spontaneous reaction to spontaneous ones.

Question 40

What is calorimetry?

Answer 40

The process of measuring transferred heat .

Question 41

What is the zeroth law of thermodynamics?

Answer 41

objects that are in thermal equilibrium only when their temperatures are equal.

Question 42

Specific heat is what?

Answer 42

defined as the amount of energy required to raise the temperature of one gram of a substance by 1 kelvin or degree Celsius.

Question 43

heat capacity

Answer 43

=mc

Question 44

Calorimeter equation

Answer 44

q system= -q surroundings mct system= mct surrounding

Question 45

Calculating the the phase changes of ice to gas

Answer 45

calculate the heat transfer and the phase changing steps, each step will give a certain amount of energy and the add them all together. Use 1= mcT and q=mL

Question 46

What is bond dissociation energy?

Answer 46

the average energy that is required to break a particular type of bond between atoms in the gas phase, and is an endothermic process.

Question 47

What are some combustion reactions?

Answer 47

with oxygen, diatomic fluoride, and Hydrogen.

Question 48

How does ΔS and ΔH affect ΔG?

Answer 48

ΔG= ΔH-TΔS if both are positive G is spont at high temp . if H is positive and S is neg than it is nonspont at all T If H is negative and S is positive it is spont at all T If H is negative and S is negative is spont at low temp .

Question 49

Rate of reaction depends on...

Answer 49

Ea (activation energy), not G