Thermodynamics

Question 1

What is a thermodynamic system?

Answer 1

It is a system that is a part of the universe under consideration

Question 2

What is an isolated system?

Answer 2

Not exchanging heat, matter or work with their environment

Question 3

What is a closed system?

Answer 3

Exchanging energy but not matter with their environment

Question 4

Adiabatic boundary

Answer 4

Not allowing heat exchange

Question 5

Rigid boundary

Answer 5

Not allowing exchange of work

Question 6

Open system

Answer 6

free exchange with the environment

Question 7

Boyle, Charles and Gas Law

Answer 7

Volume is inversely proportional to pressure
Volume is directly proportional to temperature
number of moles is directly proportional to volume

Question 8

what is the ideal gas equation?

Answer 8

pV = nRT

Question 9

What are the assumptions of an ideal gas?

Answer 9

Negligible molecular volume
No intermolecular interactions
All collsions are elastic

Question 10

What is the equation that means temperature is directly proportional to the total kinetic energy?

Answer 10

1/2Mc^2 = 3/2RT

Question 11

how can you increase the speed of an atom?

Answer 11

work done
or heat supplied

Question 12

what is the first law of thermodynamics?

Answer 12

difference in internal energy is equal to the workdone + heat supplied

Question 13

Complete the blank:
In a ____ process a system changes to the arrangement with highest statistical weight

Answer 13

spontaneous

Question 14

what is temperature directly proportional to in an einstein solid?

Answer 14

energy density
number of quanta per oscillator

Question 15

what is the zeroth law of thermodynamics?

Answer 15

bodies in contact come to thermal equilibrium

Question 16

what if the formula for the total number of ways of filling up boxes? indistinguishable particles - distinguishable boxes

Answer 16

W = N^Q
n is the number of boxes
Q is the number of particles

Question 17

what about in indistinguishable particles - indistinguishable boxes?

Answer 17

W = ( Q+N -1)!/Q! (N-1)!

Question 18

how does the energy density relate to T?

Answer 18

Qe/N = KbT

Question 19

relate an equation with ni/no and T

Answer 19

ln(ni/n0) = iE/kbT

Question 20

what is the third law of thermodynamics?

Answer 20

the entropy of a perfectly crystalline substance is zero at T = 0K

Question 21

what is the entropy change equivalent to?

Answer 21

S = kb x lnW

Question 22

What is the second law of thermodynamics?

Answer 22

During a spotaneous process, the entropy of the universe increases

Question 23

What is Helmholtz Energy?

Answer 23

change in A = change in U - T x change in S

Question 24

how do you calculate total entropy?

Answer 24

total entropy = entropy of system + entropy of surroundings

Question 25

what is enthalpy change?

Answer 25

the heat required under constant pressure to transform a system between two states

Question 26

Gibbs Energy Change

Answer 26

G = H - TS when negative process is spontaneous

Question 27

What is the heat capacity of a noble gas? How does that compare to a solid?

Answer 27

Cv = 3/2R Cv = 3R

Question 28

Equipartition of energy

Answer 28

In a system in thermal equilibrium, on average, an equal amount of energy will be associated with each indepenednt energy state system of particles in equilibrium at absolute temperature will have the energy 1/2kT, where k is the boltzmann constant

Question 29

What does equipartition indicate?

Answer 29

each active degree of freedom contributes to R/2 to the heat capacity

Question 30

What happens at constant pressure to make entropy equivalent to temeprature?

Answer 30

dS = dH/T

Question 31

What do you use a bomb calorimeter for?

Answer 31

To determine the enthalpy change of a reaction

Question 32

Describe differential thermal analysis

Answer 32

furnace with refernce crucible and sample crucible graph of Temperature against Time two straight lines positive slope of furnace and reference the sample dip towards the bottom, little dip endothermic then exothermic with a peak at the top

Question 33

What are the melting points indicative iof?

Answer 33

The chemical species in the sampel

Question 34

What is a limitng factor of differential thermal anylisys?

Answer 34

Yields chemical information Does not tell anything about energy changes associated with chemical processes

Question 35

Differential scanning calorimetry - two methods

Answer 35

Power differential heats both sample crucible and reference crucible so that the heating block is the same measures the difference in power that must be supplied to meet the condition heat flow in a furnace but inseted in a calibrated metal block they will try to come to thermal equilibrium by transporting heat through the metal heat flow against time both come with a plot glass transition temperature crystallisation temperature melting temperature

Question 36

what is a glass transition temperature? what about crystallisation?

Answer 36

amorphous material, hard + brittle to soft and rubbery amorphous/semi-crystalline to a regular crystal structure

Question 37

what happens in thermal gavimetric analysis?

Answer 37

mass is also measured if mass increases a chemical reaction can be indicated

Question 38

what is the standard enthalpy change?

Answer 38

change in enthalpy for a process at that temperature in which the intial and final substances are in their standard state

Question 39

hess's law

Answer 39

heat evolved or adsorbed in a chemical process is the same as the process take place in one step or several

Question 40

how can you find delta H at a different temperature?

Answer 40

delta r H (T2) = delta r H(T1) + delta rcp x deltaT

Question 41

how can you find delta S at a different temeprature?

Answer 41

delta r S (T2) = delta r S (T1) + delta rcp x ln(t2/T1)

Question 42

what is the activity of an ion related to? what about gases?

Answer 42

activity ion = activity coefficient x concentration ion/ standard concentration activity ion = activity coefficient x pressure/standard pressure

Question 43

what is the reaction quotient?

Answer 43

activity of product/ activity of reactant

Question 44

what is the equilibrium point?

Answer 44

dG/dn = 0

Question 45

gibbs energy of a species A

Answer 45

G Am = G0am + RTlna

Question 46

what happens at equilibrium?

Answer 46

delta rG0 = -RTlnK

Question 47

What is unity?

Answer 47

The activities of solids/pure liquids are unity

Question 48

Equilibrium Constant in Gas and Solids

Answer 48

ep 1 lecture 9

Question 49

arhenius definition for acid and base

Answer 49

acid ionises in water to give h+ions base dissociates in water to yield OH- ions

Question 50

lowry bronsted definition for acid and base

Answer 50

acid is a proton donor and base is a proton acceptor

Question 51

amphoteric

Answer 51

acts both as an acid and base e.g. water

Question 52

equilibrium constant of water at 25 degrees C

Answer 52

1 x 10^-14 pH of 7

Question 53

what is the limitng factor in the standard gibbs energy?

Answer 53

only allows us to predict whether a reaction is spotaneous under standard conditions

Question 54

gibbs energy of reaction and Q

Answer 54

delta r G = delta r G0 + RTlnQ the reaction quotient

Question 55

what happens in a reversible change

Answer 55

we get the maximum amount of work from the system

Question 56

what is efficiency?

Answer 56

delta G / delta H = 1 - Tdelta S / delta H

Question 57

what is the gibbs energy change?

Answer 57

maximum non pv work available from the system non-pv work available when the system is operated reversibly

Question 58

what is the maximum efficiency of a heat enginer?

Answer 58

= T1-T2/T1

Question 59

what is the molecular partition function?

Answer 59

q = sum of e^(-ei/kT)

Question 60

the internal energy and q

Answer 60

E = -N (dlnq/db)