Physical Chemistry and Material Science Flashcards
System that allows exchange of both matter and energy
Open System
System that allows exchange of energy and not matter
Closed System
System that does not allow exchange of both matter and energy
Isolated System
PV=k
Boyle’s Law or Mariotte’s Law
V/T=k
Charles’ Law
P/T=k
Gay-Lussac’s law
Achieved at high temperature and low pressure
Ideal Gases
Where intermolecular forces (IMFA) are significant
Real Gases
What is the significance of Modified Equations of State?
accounts for pressure and volume changes due to IMFA
For a real gas, what causes the deviation from the ideal pressure at a molecular level?
Intermolecular forces of attraction of the molecules with one another
When gas molecules collide, they experience _____ collision.
Perfectly elastic
0th Law of Thermodynamics
(Proponent, Definition)
Ralph Howard Fowler
If TA=TB and TB=TC, then TA=TC
1st Law of Thermodynamics
(Proponent, Definition)
Rudolf Julius Emanuel Clausius
-Law of Conservation of Energy
-Energy can’t be created/destroyed, only transformed
-Energy of universe is constant
-The total energy of any system and its surroundings is conserved.
2nd Law of Thermo (Clausius Statement)
(Proponent, Definition)
A device that solely transfers heat from low to high temperature is impossible. Work is required.
2nd Law of Thermo (Kelvin-Planck Statement)
A) Impossible for device to completely convert heat to work (n < 1, and n < n,Carnot), effect to surroundings always exist.
B) Impossible for any device operating on a cycle to receive heat from a SINGLE RESERVOIR ONLY and produce a net amount of work. A hot and cold reservoir are required.
3rd Law of Thermodynamics
Walther Hermann Nernst
- S=0 at absolute zero (especially perfect crystals), then S>0 for everything else
Carnot Theorem
Nicolas Sadi Carnot
-n,Carnot = n,max (No engine is more efficient than Carnot engine)
- Any reversible engine between two heat reservoirs is a Carnot Engine
For Carnot engines:
Its efficiency depends only on _____ and not the working substance of the engine.
temperature levels (Tc and Th)
Which of the following is not conserved in any process?
a. Mass
b. Energy
c. Momentum
d. Entropy
Entropy
Increasing the temperature of the cold reservoir _____ the Carnot efficiency
Decreases
If the entropy of a system decreases, the entropy of its surroundings
Must always increase
(Since dS,univ > 0)
Defines entropy in terms of the number of ways that the molecules can be arranged amongst the energy states, subject to the arrangements having the same overall energy.
Boltzmann formula
What does Clausius Inequality say?
- Entropy increases for spontaneous processes
- dS > 0 indicated spontaneity
What does Nernst Heat Theorem say?
Related to Third Law
Entropy change approaches zero as the temperature approaches zero:
* ΔS → 0 as T → 0
* Provided all substances are perfectly ordered.
Conditions wherein the difference between gas and liquid starts to disappear
Critical Parameters
Father of Thermochemistry
Germain Henri Hess
The amount of heat absorbed when CO2 gas reacts with a solid CaO to form solid CaCO3 is measured in a bomb calorimeter. The data obtained give a direct measure of:
ΔU
AKA Constant Volume Calorimeter
Bomb Calorimeter
AKA Constant Pressure Calorimeter
Adiabatic Flame Calorimeter
The energy required to completely separate one mole of a solid ionic compound into gaseous ions
Lattice energy
The equilibrium intensive state of a system is described by specifying the temperature, pressure, and:
Mole fractions
Determine whether the changes in entropy (ΔS) and enthalpy (ΔH) are positive, negative, or near zero.
1. Ethyl alcohol evaporating from glass container
2. A diatomic molecule dissociates into atoms
3. Charcoal is burned to form CO2
and water
- ΔH>0, ΔS>0;
- ΔH>0, ΔS>0;
- ΔH>0, ΔS>0
It is the property of a fluid that is caused by shearing effect of a fluid layer moving past another layer.
Viscosity
Is Van der Waals EoS independent of critical parameters?
No
State the Principle of Corresponding States
Substances with equal Pr, Tr and Vr have the same properties
Temperature at which property of real gas becomes ideal
Boyle Temperature
The tendency of gas to flee or escape
Fugacity Coefficient
Gas behavior if fugacity coef is:
*>1
*=1
*<1
*>1: Repulsive
*=1: Ideal
*<1: Attractive
Indicates a temperature change upon isenthalpic gas expansion
Joule-Thomson Coefficient
Most gases cools down during isenthalpic processes except __
Hydrogen and helium
Temperature at which Joule-Thomson Coefficient shifts sign
Inversion Temperature
Gas behavior if Joule-Thomson Coefficient is:
*>0
*=0
*<0
*>0: Attractive
*=0: Ideal
*<0: Repulsive
Most compact physical state having the strongest interaction between particles
Solids
Solids with fixed geometric pattern and melting points
Crystalline solids
Solids with irregular geometric pattern and melting points.
Amorphous solids
Differentiate Types of Solids (based on composition, melt point, thermal and electric conductivity):
Ionic
Molecular
Polymeric
Network Covalent
Metallic
Amorphous
Ionic: crystals made of ions (NaCl salt)
High melt pt, low electric and thermal conductivity
Molecular: crystals made of molecules (ice)
Low melt pt, low electric and thermal conductivity
Polymeric: giant molecules; may be crystalline, amorphous or semicrystalline (rubber, plastics, proteins), low electric and thermal conductivity
Network Covalent: large number of covalent bonds (diamond and quartz)
High melt pt, low electric and thermal conductivity
Metallic: held together by metallic bonds (gold)
Varying melt pt, high electric and thermal conductivity
Amorphous: randomly arranged molecules. No melting point (soot, tar, glass)
Solids characterized by an array of positive ions immersed in a sea of valance electrons
Metallic
Solids that lack a regular three-dimensional arrangement of atoms
Amorphous Solids
Solids joined by van der Waals, hydrogen bonds or Dipole-dipoles
Molecular Solids
Solids that cannot be melted
Covalent Solids
Reason for good electric and thermal conductivity of Metallic solids
mobility of the delocalized electrons
The best electrical conductor
Silver
Other term for Solidification
Crystallization
Optically transparent fusion product of inorganic materials that has cooled to a rigid state without crystallizing
Glass
Common form of elemental Carbon
- Diamond
- Graphite
- Buckyballs
- Nanotubes
- Soot
The only Network Covalent solid with good thermal conductivity
Diamond
Covalent solid with good electric conductivity
Graphite
Types of Crystal Lattice
Simple Cubic
-# atoms: 1
-Coordination Number: 6
-Packing Efficiency: 52%
Body Centered Cubic
-# atoms: 2
-Coordination Number: 8
-Packing Efficiency: 68%
Face-Centered Cubic
-# atoms: 4
-Coordination Number: 12
-Packing Efficiency: 74%
Branch of chemistry that qualitatively and quantitatively describes the energy changes that occur during chemical reactions
Thermochemistry
Reactions that take place in a single phase (i.e., liquid, gas, or solid)
homogeneous reactions
Reactions that occur at surfaces between phases
heterogeneous reactions
When does a crystal get hydrated?
When H2O becomes an integral part of the crystal lattice
Property most often used as measure of thermodynamic potential
Gibbs Free Energy
Basis of Phase Diagrams of single component systems
Clapeyron Equation
dP/dT = dS/dV,m
Describe Trouton’s Rule
Molar entropies of vaporization of all substances are equal IF IMFA is not significant
dS,vap = 88 J/mol*K (nasa HB)
Trouton’s rule fails for ___ hence it is frequently used for ___
Highly polar liquids
frequently used for Hydrocarbons
The unit-lateral deformation of a body under stress divided by the unit longitudinal deformation is known as
Poisson’s ratio
The ability of a solid substance to resist abrasion and surface deformation.
hardness
The measure of a material’s resistance to localized plastic deformation.
hardness
The maximum stress that can be sustained by a structure in tension
tensile strength
The capacity of a material to absorb energy when it is deformed elastically and then, upon unloading, to have this energy recovered.
resilience
The property that is indicative of a material’s resistance to fracture when a crack is present.
toughness
What is the ability to return to the original shape after being deformed called?
elasticity
It is the ability to be shaped
malleability
It is a measure of the degree of plastic deformation that has been sustained at fracture.
ductility
A material that experiences very little or no plastic deformation upon fracture
brittle
What does the Clapeyron Equation tell us?
T and P change to keep their chemical potentials equal
Assumption in Clapeyron Equation
Molar volume of liquid negligible
Vapor obeys ideal gas laws
Describe Gibbs Phase Rule
F = 2 + C - P - R
*Used to determine degrees of freedom of a system.
*number of intensive variables required to describe and entire system
What does the Gibbs-Duhem equation calculate?
G = uAnA + uBnB + ……
Gibbs-Duhem equation relates COMPOSITION in liquid phase and the:
-fugacity
-partial pressure
-activity co-efficient
at constant temperature & pressure.
For miscible systems, the boiling point of the solution is
Between the boiling points of the two liquids
Describe colligative property
Property that depend on the quantity of solutes and nature of solvents, and NOT the nature of solutes
When BPE and FPD happens?
BPE - at high T, solute causes increased IMFA hence higher energy required to boil
FPD - at low T, solute causes decreased IMFA hence solvent freezes at lower T
Determination of Molecular Mass via:
1. Freezing pt
2. Boiling pt
3. Osmotic pressure
- Freezing pt:
Cryoscopy - Boiling pt:
Ebullioscopy - Osmotic pressure:
Osmometry
In colligative props, presence of solute causes ____
- decrease in chemical potential
- increase in entropy
In osmosis, at equilibrium, chemical potential of the pure solvent side should be _____ chemical potential of the side with solute.
equal to
Rank in terms of vapor pressure lowering and ions made?
a. sucrose, C12H22O11
b. Aluminum chloride, AlCl3
c. Table salt, NaCl
d. Sodium sulfate, Na2SO4
a. sucrose, i=1
b. AlCl3, i=4
c. NaCl, i=2
d. Na2SO4, i=2
Which of the following is not conserved in any
process?
a. Mass
b. Energy
c. Momentum
d. Entropy
Entropy
The equilibrium intensive state of a system is described by specifying the temperature, pressure, and _____
Mole fractions
____ is a state function that determines whether a physical change or chemical reaction can occur simultaneously in a closed system
entropy
(spontaneously dapat)
Describe Gibbs-Duhem Theorem
Describes relationship between chemical potential of a system and its composition while maintaining equilibrium
Differentiate Henry’s Law and Raoult’s Law
Define Ideal Solution and Non-ideal Solutions
- Raoult’s Law (Pa=x*Pt) for ideal solutions
- Henry’s Law (Pa=H*xa) for non-ideal dilute solutions
- Ideal solution: negligible molecule size difference and intermolecular interactions.
- Non-Ideal solution: heightened interactions
Henry’s law states that ____
Pa = H*xa
At constant temperature, amount of gas dissolved in liquid is directly proportional to the partial pressure of that gas in equilibrium with that liquid.
Differentiate Positive and Negative Deviating Systems (Henry’s Law) in terms of:
Positively-Deviating System
*Vapor pressure: > P,ideal
*Polarity: Different (polar and nonpolar)
* Behavior: Endothermic Expansion
*Example: Ethanol-Hexane
Negatively-Deviating System
*Vapor pressure: < P,ideal
*Polarity: Similar (both polar/ nonpolar)
* Behavior: Exothermic Contraction
* Example: Acetone-water
Maximum amount of the solid that will dissolve in a given amount of a particular solvent at a given temperature.
Solubility
Explain “like dissolved like”
polar dissolved polar
nonpolar dissolved nonpolar
Effect on temperature on solubility of solids, liquid and gasses in liquid
Increased solid and liquid solubility
Decrease gas solubility
Define Colloids (and physical characteristics)
Dispersion of NANOSCALE (1nm to 1000nm) particles throughout the continuous phase.
* scatter light (Tyndall effect)
* form stable dispersions not easily settleable
Way to crystallize the excess solute is to add a crystal of the solute
seeding
Happens when elevated temperature affects aquatic life. What do we call this phenomena?
thermal pollution
Effect on PRESSURE on solubility of solids, liquid and gasses in liquid
Negligible increase in solid and liquid solubility
Substantial increase gas solubility (carbonated softdrinks)
Why a bottle of beer or a carbonated beverage foams when it is opened?
Henry’s Law: Pa=Pa,sat*xa
Lower external pressure Pa, Lower solubility of gas
Differentiate Solutions, Colloids and Suspension
Colloids: nanoscale size particles (1nm to 1000nm)
Solutions: smaller than nano
Suspensions: larger than nano. Separates in standing
The scattering of light by colloidal-size particles
Tyndall effect
Liquid droplets or solid particles dispersed throughout a gas
aerosols
Liquid droplets dispersed throughout another liquid.
emulsion
Solid particles dispersed in a liquid.
sol
Colloidal-sized particle formed in water by the association of molecules or ions that each have a hydrophobic end and a hydrophilic end.
micelle
Solution wherein no additional solute can be dissolved
Saturated solution
Solution wherein additional solute can still be dissolved
Undersaturated solution
Heat change that results when 1 mole of the compound is formed from its elements at a pressure of 1 atm.
Standard heat of formation
What is the standard heat of formation of elements in their most stable form? Why?
- zero
- used as reference point such that Standard heat of formation of COMPOUNDS is the summation of heats from its elements.
Explain Hess’s law
“When reactants are converted to products, the change in enthalpy is the same whether the
reaction takes place in one step or in a series of steps.”
* Enthalpy involved in a process can be broken down into steps
* dH = sum(vH,p) - sum(vH,r)
Direct Method to determine Heat of Reaction
*If substance easily formed
e.g. C (graphite) + O2 –> CO2
change from a gas to a liquid
Condensation
change from a liquid to a solid
solidification
Why enthalpy of formation for an element in its elemental state or naturally occurring state is always equal to ZERO?
- Naturally occuring = most stable
- It takes no energy to form a naturally occurring compound.
Why is it when diluting, the acid is added to water and not the other way around?
Heat of Dilution
- Dilution of acid with water is highly exothermic. The more water is added to acid, the more heat it releases to surroundings causing it to boil.
Explain Excess properties
M,xss = M,actual - M,ideal
Difference between the actual property solution and its value if it were to be an ideal solution at the same T and P and composition is called
Describe Helmholtz Free Energy
(Proponent, Equation, Definition)
- Hermann Ludwig Ferdinand von Helmholtz
- A=U-TS
- Maximum work by system at T=k
- The energy that can be transformed into uniform motion (U is total energy, TS is disordered motion, their difference is uniform motion)
Describe Gibbs Free Energy
(Proponent, Equation, Definition)
Josiah Willard Gibbs
G=H-TS
Maximum (non-expansion) work by system at P&T=k
Frequently used to determine system’s chemical potential (chem pot = G/n)
Criteria for Equilibrium for:
Entropy
Gibbs Free Energy
Helmholtz Free Energy
LAHAT dS = dG,T,P = dA,T,V = 0
Criteria for Spontaneity for:
Entropy
Gibbs Free Energy
Helmholtz Free Energy
For Gibbs and Helmholt: dG < 0 & dA < 0
For Entropy: dS > 0
What does Clapeyron calculate?
slope of a phase boundary.
Basis for phase diagrams
Clapeyron equation
What does Clausius Clapeyron equation calculate?
Boundary between a liquid phase and its vapor phase.
Describe Azeotropes and their Boiling points
- When liquid-vapor system, with constant boiling point because their liquid and vapor composition is equal
- Hard to distill, requires additional mass transfer agent
- Boiling point between the more and less volatile component
Pick out the system with maximum boiling azeotrope at 1 atm.
A. Acetone chloroform
B. Ethyl alcohol-water
C. Benzene-ethyl alcohol
D. None of these
Acetone chloroform
Pick out the system with minimum boiling azeotrope at 1 atm.
A. Benzene-toluene
B. Ethyl alcohol-water
C. Hydrochloric acid-water
D. All of the above
Ethyl alcohol-water
A minimum boiling azeotrope is exemplified by
A. Toluene-benzene
B. Acetone-carbon disulphide
C. Water-isobutyl alcohol
D. None of these
Acetone-carbon disulphide
Which of the following binary systems is an example of a maximum boiling azeotrope?
A. Water-hydrochloric acid
B. Acetone-carbon disulphide
C. Water-ethyl alcohol
D. N-heptane-n-octane
Water-hydrochloric acid
With increase in temperature, the solubility of gases in liquids, at fixed pressure ___
Decreases
__________ is the temperature at which a gas-vapor mixture becomes saturated, when cooled at constant total pressure out of contact with a liquid.
Dew point
Branch of chemistry that deals with the interconversion of electrical energy and chemical energy
Electrochemistry
Experimental apparatus for generating electricity through the use of a spontaneous reaction
galvanic cell or voltaic cell
Electrode in galvanic cell at which oxidation and reduction occurs, RESPECTIVELY
RedCath, AnOx
Anode: Oxidation
Cathode: Reduction
Conducting medium through which the cations and anions can move from one electrode compartment to the other.
salt bridge
What happens without the salt bridge?
There will be buildup of positive charge in anode compartment, and negative on cathode compartment.
PREVENTS GALVANIC CELL FROM WORKING
The voltage across the electrodes of a galvanic cell
Cell potential or Electromotive force (emf)
Voltage associated with a reduction reaction at an electrode when all solutes are 1M and all gases are at 1 atm
standard reduction potential
The more negative the standard electrode potential is, the more likely the reaction is to proceed from ___ to ___
right to left
Recall: negative E and positive dG is nonspontaneous
The more positive the standard reduction potential, the greater the electrode’s tendency to be _____ and the higher its strength as an _____ agent
the greater the electrode’s tendency to be REDUCED and the higher its strength as an OXIDIZING AGENT
Strongest oxidizing agent
F2
Has highest reduction potential
Weakest oxidizing agent
Li+
Has lowest reduction potential
Why does changing the stoichiometric coefficients of a half-cell reaction does not affect the value of standard reduction potentials?
Because electrode potentials are intensive properties
Weakest oxidizing agent
Li+
Has lowest reduction potential
Maximum work a cell can achieve
Equal to electromotive force and Gibbs free energy
w,max = dG = w,ele = -nFE,cell
Quantity of electricity carried by 1 mole of electrons
Faraday’s constant
96,500 C / mole e-
Gives the relationship between the cell emf and the concentrations of the reactants and products under non-standard-state conditions.
Nernst equation
If the entropy of a system decreases, the entropy of its surroundings ____
Must always increase
For a particular chemical reaction, ΔH˚ is positive and ΔS˚ is negative. Which of the ff statements is TRUE?
A. The reaction will be spontaneous only if the magnitude of ΔH˚ is large enough to cover the unfavorable entropy change.
B. The reaction will be spontaneous only if the magnitude of ΔS˚ is large enough to overcome the unfavorable enthalpy change.
C. The reaction will be spontaneous regardless of the magnitudes of ΔH˚ and ΔS˚.
D. The reaction cannot be spontaneous.
dG=dH-TdS
D. The reaction cannot be spontaneous.
In which of the following cases does entropy decreases?
A: Polymerization of Styrene and Butyl Acrylate
B: Dissolving Mohr’s salt in water
C: Expansion of high purity hydrogen gas
D: Melting silver ingots
A: Polymerization of Styrene and Butyl Acrylate
When steam condenses into water at 90 deg C, the entropy of the system decreases. Which of ff is true?
A: Entropy of the universe also decreases
B: Entropy of the surrounding increases to the same extent to which entropy of the system decreases
C: Entropy of the surrounding also decreases
D: Entropy of the surrounding increases to a greater extent than the decrease in the entropy of the system
D: Entropy of the surrounding increases to a greater extent than the decrease in the entropy of the system
For the following process occurring at 100 deg C and 1 atm:
H2O (l) —–> H2O (g)
Which among the following statements is correct?
A: delta S_system > 0 & delta S_surrounding > 0
B: delta S_system < 0 & delta S_surrounding > 0
C: delta S_system < 0 & delta S_surrounding < 0
D: delta S_system > 0 & delta S_surrounding < 0
D: delta S_system > 0 & delta S_surrounding < 0
Common formes of elemental Carbon
- Diamond
- Graphite
- Buckyballs
- Nanotubes
- Soot
