All Units Flashcards
Molecules vs Ions
Molecules
- Covalent
- All states
- Simplest = molecules
Molecules vs Ions
Ions
- Electrostatic Forces of Attraction
- Solids with 3d crystal lattices
- No prefixes with exceptions
- can become hydrates
Types of Reactions
Decomposition
- Breaking down compound to form simpler compounds/elements
- Endothermic
Types of Rxns
Ionization
- Rxn with polar covalent ions to ions in H2O
Types of Rxns
Dissociation
- Separation of ions in H2O
Types of Rxns
Melting
- Solid ==> liquid
Solubility
Soluability Rule
- Salts with Na+, K+, NH4+, NO3-
Solubility
Insolubility Rule of Thumb
- max concentration less than .01 M, insoluable
Conduction and Electrolytes
Strong Electrolytes
- More ions = More Strength
Conduction and Electrolytes
Weak Electrolytes
- Weak acids and Bases
Conduction and Electrolytes
Non-Electrolytes
- nonpolar componds/ org compounds except carboxylic acids and amines
Thermodynamics Introduction
Heat
- speed or Energy of particles
Thermodynamics Introduction
Energy
Capacity to do work
Thermodynamics Introduction
Work
Action of Force through ∆x
Thermodynamics Introduction
Total Energy of object
- KE: E associated with motion ==> Thermal Energy
- PE: (bond energy); energy associated with position or composition
Energy Units
1 L*atm
101.325 J
Energy Transfer
Energy Transfer between system and surroundings
- Sys decrease(-) = Increase surroundings(+)
- Sys increase(+) = Decrease surroundings(-)
Definition of Specific Heat(c)
- Amount of energy required to raise 1 gram by 1 C
Exothermic vs Endothermic
Exothermic
- Graph increases then ends lower than starting level(∆ PE = -)
Exothermic vs Endothermic
Endothermic
- Graph increases then ends higher than starting level(∆ PE = +)
Types of Systems
Open
- matter and Energy exchanged with surroundings
Types of Systems
Closed
- Only Energy may exchange with surroundings but not matter
Type of System
Insulated
- No energy or matter exchanged with surroudings
Transfer between system and surroundings
Energy Transfer with work and heat
- E = q + w
Transfer between system and surroundings
Heat/Q
- Driving Force = ∆T
Transfer between system and surroundings
Work/W
- Driving Force = - P * ∆V
- W= Fd
- Compression = (+)
- Expansion = (-)
Heat
Heat Capacity
- C
- q=C∆T
- slope of Q and ∆T
- units = J/C
- Extensive: Depends on mass
Heat
Specific Heat
- c
- c = Q/m/∆T
Calorimeter
Bomb
- Constant Volume
- qcal=Ccal* ∆T
- qcal = qrxn = ∆Erxn
Calorimeter
Coffee-Cup
- Constant Pressure
- qcal=Ccal* ∆T
- qcal = qrxn = ∆Erxn
Standard Enthalpy of Formation
Standard State
- State of Pure Substance at l atm P and Temp of Interest(25 C)
Standard Enthalpy of Formation
Standard Enthalpy of change
- ∆H^o
- ∆H of reactants and products
Standard Enthalpy of Formation
Standard Enthalpy of Formation
- ∆H when 1 mol substance formed from compund standard state elements
Standard Enthalpy of Formation
Standard Enthalpy of Formation Equation
- ΔHoreaction=ΣΔHof(p)−ΣΔHof(r)
Hess’ Law
Hess’ Law
- If equation can be explained as sum of 2+ equations, ∆ H for desired equation = ∆ H sum of other equation
Phase Changes
Heat absorbed into system
- q > 0
- melting, vaporization, sublimation
Phase Changes
Heat released into system
- q < 0
- freezing, condensation, deposition
Gas Laws
Interaction of External and Internal Pressure
- No change: Internal Pressure = External Pressure
- Compression: Internal Pressure < External Pressure
- Expansion: Internal Pressure > External Pressure
Gas Laws
Calculating Pressure under liquid
Equations
- With Atmosphere: P(H2O)[“Column Pressure”] + P(atm)[atmospheric/ barometric pressure]
- In Vaccum: P(H2O)[“Column Pressure”]
Properties of Gases
What is a Vapor?
- Gaseous state of substance usually a liquid or solid at room temp and pressure
Properties of Gases
Gas Elements
that are gases at Room Temp
- Noble gases(are isolated atoms)
- Diatomic Gases: H2, N2, F2, O2 and Cl2
- HCl, NH3, CO2, N2O, CH4, HCN
Gas Characteristics
Gas Characteristics
- Gases assume shape and volume of container
- Move in constant, random motion but in straight line
- Gas Density less than Liquid Density or Solid Density
- It is highly variable[*Increased T –> Decreased D vs Increased P –> Increased D] *
- Gases form Homogeneous Mixture with each other in any proportion [0 rxn = mutually miscible]
Pressure
Pressure equation
- F/a
- dgh[in Pascals]
- mmHg is a measure as well as a pressure unit
Monometer
What is a Monometer
- Measures gas P
- P = difference of liquid height
- 2 types
1. Close-end(vaccum)
2. Open-end(atm)
Pressure
Conversions
1 atm = 760 mmHg = 760 Torr = 101.325 kPa = 1.0325 bar = 14.7 lb/in^2 = 101,325 N/m^2
Monometer
Monometer Equations
- For Close-Ended: Pgas = Δh(liquid)
- For Open Ended:
1. Pgas = Δh(liquid) + Patm[Pgas>Patm]
2. Pgas = Δh(liquid) - Patm[Pgas
Ideal Gas Law Equation
What is STP?
- Standard Temperature and Pressure
- 273.15 K and 1 atm
Ideal Gas Law Equation
What is an Ideal Gas?
- @ higher Temperature: More gases
- @ Lower pressure: More space
- Rules:
1. Gases move randomly
2. No attraction between particles
3. “Infinite” volume and and Volume of gas not important
4. Obeys simple gas laws: Boyle, Charles, Avagadro
MCQ?
Ideal Gas Law Equation
Boyle, Charles, Avagadro Equations
- Boyle: V=1/P
- Charles: V=T
- Avagadro: V=n
MCQ?
Ideal Gas Law Equation
Combined Gas Law
P1xV1/(n1xT1)=P2xV2/(n2xT2)
Ideal Gas Law Equation
Units
- P = any
- V = any
- n= mol
- T = K
Ideal Gas Law Equation
Types of R
- R = 0.08206 liter·atm/mol·K
- R = 62.36 L·Torr/mol·K or L·mmHg/mol·K
Density equation
D=MP/RT
Molarity Equation
M=mRT/(PV)=DRT/P
Stoichiometry with Gases
Law of Combining Gas Volumes
- Ratios from balanced equations can be in L instead of mol when Same Temp and P
- If not use ideal gas law as part of stoic(Ex. 1/P to get rid/add Pressure)
Dalton’s Law of Partial Pressure
Equation for P.P.
- Ptot=P1+P2+…Pi
Mole Fractions of Gases
Equations
- Xi=ni/ntot=Pi/Ptot
- Mole % = Mole Fraction * 100%
Kinetic Energy Molecular Theory
Postulates
- Gas particles so small and distance so large that individual volume is negligible
- Particles in Constant Motion
- No Forces between Particles(No Attraction or Repulsion)
- Average Ke proportional to T(in K)
Kinetic Energy Molecular Theory
Deviation of Ideal Gas Law Equation
- P=1/3(N/V)mū^2
- N= # of molecules
- m = mass of 1 mole
- ū^2 = Average of squared velocities
Kinetic Energy Molecular Theory
Proportions
- KE proportional to T
- Urms proportional to √1/M
- Urms proportional to √T
Kinetic Energy Molecular Theory
Equalities
- U1/U2 = √(M2/M1)
- t1/t2 = √(M1/M2)
Kinetic Energy Molecular Theory
Root Mean Square Velocity Equation
- √(ū^2) = √(3RT/M)
1. R = 8.314 J/(mol·K)
2. M= kg/mol - OR sum of speeds squared divided by number of molecules, then sqrted
Kinetic Energy Molecular Theory
What does Volatile mean?
- Molecules that have weaker IMFS; easier to go from liquid to gas
Kinetic Energy Molecular Theory
What does Effusion Mean?
- Gas escapes container through hole into an evacuated chamber
- Diffusion Properties still in play(Go from high to low pressure)
- Effusion inversely proportional to √M
Non-Ideal Gas Behavior
When does Non-Ideal Gas Behavior happen?
- Low Temp, High Pressure
- As Temp increases, deviation decreases: Less IMFs because of less interaction
- As Pressure increases, deviation increases: Actual volume available will be greater than predicted because gas molecules take up more space
Non-Ideal Gas Behavior
Van der Waals Equation
- P=nRT/(V-nb) - (n^2)(a)/(V^2)
1. a and b gas constants
2. nb = accounting for size of gas molecules
3. n^2a = accounting for IMFs
Electrons
How Light Energy is Determined?
- wavelength
- frequency
- energy
Electrons
When are wavelengths seen?
When electrons return to ground level
Electrons
Planck’s Constant
- h
- 6.022E-34 Jᐧs
- Slope of E∝V
Properties of Light
What is Electromagnetic Radiation
- EMR
- Properties of Light
Properties of Light
Wavelength
- Length of one wave
- Meters
- 𝝀
Properties of Light
Frequency
- Number of wavelengths(or cycles) per sec passing a point
- 1/s or s^-1 or Hz
- 𝛎
Properties of Light
Speed of Light
- 2.998E8 m/s
- c
Properties of light
Amplitude
- Higher is Brighter while Lower is darker
Properties of Light
Equations for Energy, and Light Parts
- c = 𝝀 ᐧ 𝛎
- E = h𝛎
- E = hᐧc/𝝀
* Is the Energy of 1 photon
What are Photons?
Particle side of electrons
Planck’s Work
What does delocalized mean?
the electron is not with a certain atom or nucleus
Planck’s Work
What is a Quantum
A packet of Energy for an electron to jump to the next electron level
Einstein’s work
What is Photon Energy related to?
- Ephoton ∝ 𝛎
- Ephoton ∝ 1/𝝀
PES equation
Ephoton = KEelectron + BEelectron
- BE = binding energy
Bohr’s Work
Energy Equation to move electron in Hydrogen
NOT IMPORTANT FOR TEST
ΔE = (-2.178E-18 J )((1/nf^2) - (1/ni^2))
de Broglie’s Work
Mass Equation
h/(𝝀v)
Quantum Numbers
Types
- n = Priniciple quantum number
- l = Angular quantum number
- m = Magnetic quantum number
- ms = Magnetic Spin
Quantum Numbers
Nodes
No possibility for electron(white shell)
Quantum Numbers
Principle Quantum Number
- n
- Integral Number
- Related to size and energy of orbital
- Corresponds to Bohr’s energy level
- More n
1. Increased Orbital
2. Increased distance of electron from orbital
3. Increased Energy
4. Decreased energy between orbitals
Quantum Numbers
Angular Momentum Quantum Number
- Shape
- l = 0–> (n-1) for each n val
- if n=3, possible orbitals s(0)–>d(2)
Quantum Numbers
Magnetic Quantum Number
- m
- integers specifying orbital orinetation
- Values are from -l←→+ l
- Includes 0
- Example: l = 2: m=-2,-1,0,1,2 ⇒ 5 orbitals
Quantum Numbers
Electron Spin
- Up = + .5 spin
- Down = - .5 spin
Quantum Numbers
Difference between H and Multielectron atoms
- H = subshell E levels that are degenerate(same n-int at same level)
- Multi = lower orbital energies
* Subshell of prinicple shell at different energies
Quantum Numbers
Rules for Electron Placement
- Pauli Exclusion Principle
* No 2 electrons in atom has same 4 quantum numbers
* electrons in 1/2 filled orbitals have parallel spins - Hund’s Rule
* One electron for each orbital before doubling up - Aufbau Principle
* Electron occupy lowest energy level possible
Electron Configuration
How do you write Electron Configuration
- Removal Order
- Ex) Se: [Ar] 3d^10 4s^2 4p^4
Electron Configuration
Valence Electrons
- Outermost principle shell
- Usually S or S and P
Electron Configuration
Shortcut using Noble Gases
- Can use closest previous noble gas in brackets then build the rest of the electron config from there
- Cannot use this for noble gas in ground state
Electron Configurations
Electron Configuration Exceptions
- Cr: [Ar] 3d^5 4s^1 (Same with Mo)
- Cu: [Ar]3d^10 4s^1(Same rule with Au and Ag)
Ionization Energy
What is Ionization Energy
- Minimum Energy neede to remove electron from atom or ion
Ionization Energy
Ionization Energy Requirements
- Gas State
- Endothermic
- Valence electron first
- Successive removed for 2nd etc IEs
PES
Why are X-rays used?
- Can dislodge electrons
PES
Relation between BE and KE
- Inversely Related
Magnetic Properties of electrons
Paramagnetic
- one or more unpaired electron
- attracted by a magnetic field
Magnetic Properties of electrons
Diamagnetic
- Paired electrons
- opposite spins that cancel out their magnetic fields
- Are not attracted to outside magnetic field
Magnetic Properties of electrons
How are they detected
- weighing a substance in the presence of a magnetic field
Periodic Trends
Atomic Radius
- Is the distance form the nucleus to the valence electrons
- Across Period: decreased radius due to higher effective nuclear charge
- Down Group: Increased radius due to higher n and a greater distance from the nucleus(higher n ==> higher V)
Periodic Trends
Cations
- Decreased sized compared to original
- decreased electrons with same proton number
Periodic Trends
Anions
- Increased size
- Increased electrons with same proton number
- Electron - Electron Repulsion
Ionization Energy
What is the first IE equal to?
- Binding Energy
Electron Affinity
Electron Affinity
- Energy released when neutral atoms gain electrons
1. Needs to be in gas state
2. M(g) + 1 electron –> M^1-(g) + EA etc(Successive) - Exothermic
- Increased energy leads to Increased negative EA
- Outer electrons are delocalized: can move around which leads to sea of electrons
Periodic Trends
Metallic
- Most = Bottom Left
- Least = Top Right
Coulomb’s law
Force
- (k x q1 x q2)/r^2
- q = charges
- Repulsion Force = (+)
- Attraction Force = (-)
Coulomb’s law
Energy
- (k x q1 x q2)/r
- q = charges
- E released or required to make bond
Lattice Energy
Lattice Energy
- Energy required to seperate 1 mole of an ionic solid into gaseous ions
- Higher LE ==> Higher Ionic Bond Strength
Lattice Energy
Lattice Energy Calculations
- Born-Haber Cycle = Applying Hess’ Law to its maximum
Lewis Structures
Lewis Structures
- Used to explain that atoms combined to acheieve more stable electrong configuration
Lewis Structures
Ions
- = [ ] + charge
- Ex) .Cä. –> [Ca] 2+
Lewis Structures
Coordinate Covalent Bond
- Electrons donated from one atom to another
Formal Charge
What are Formal Charges used for?
- Determines most possible lewis structure
Formal Charge
Formal Charge Equation
- FC= V.E. - (non-bonding e-) - (# of bonds)
Formal Charge
Formal Charge Rules
- FC= 0 for neutral or Ion FC= Ion charge
- FC = 0 more favorable than FC >/< 0
- Less FC > Greater FC
- Best strucure = Lewis Structure with FCs similar to ENs
* Increased EN = Increased - FC
Resonance
Resonance Theory
- Molecule/ Ions with 2+ plausible Lewis Structures with diff e- distribution
- Hybrids joined with double-headed arrows
Delocalized Electrons (Again)
- bonding electrons spread out over several atoms
Exceptions to the Octet Rule
Expanded Octet
- More than 8 electrons
- Happens in elelments that have n > 2
- Have s–>d sublevels
Valence Bond Theory
Sigma (𝞂) Bond
- 1 covalent bond where orbitals overlap
Valence Bond Theory
Domain of Double Bond
- 1
Valence Bond Theory
Hybridization
- Promotion of electrons and mixing of orbitals
- Only central atoms
Valence Bond Theory
Pi (𝛑) bond
- For bonds after single bonds
- ex) Double or Triple
- Bonding pairs are parallel to each other
Resonance Strutures
Relation to delocalized atoms
- Having them makes a structure more stable and the more you have the more stable because the lectrons are able to spread out over a larger volume
Polarizability
What is Polarizability?
- Ability to induce another nonpolar molecule to have a momentary dipole between instantaneuous and indused dipole
- Happens with Covalent Compounds
IMF Trends
LDF Trends
- Increased = Increased size
- Increased = Increased polarizability
- Increased = Greater Charge Separation
Dipole-Dipole forces
What are they?
- Polar molecules with positive “end” and negative “end” which have a permanent dipole which attracts other dipoles when closer
- Stronger than LDF
Important Note!
What to do with LDF on Test
- Write full form: London Dispersion Forces
Hydrogen bonds
Conditions
- H has to be attached to F,O,N
- Other end is also F,O,N with/without H
Hydrogen bonds
What are they?
- Strong and special d-d
- Have to write both d-d + h-b
- bet H proton and negative side of F,O,N
Surface Tension
Definition
- Amount of energy required to stretch
- Increased surface of liquid by 1 unit area
- Higher IMFs = Higher ST
Surface Tension
Adhesion
IMFs between unlike molecules
Surface Tension
Cohesion
IMFs between like molecules
Viscocity
Definition
- Measure of a fluid’s resistance to flow
- Increased T = Decreased V
- Increased V = Increased IMFs
- Tangling ==> Increased V
H2O
Properties
- Excellent Solvent
- High Specific heat
- Ice Density is less than Water because struct for spread out
Liquid-Vapor Equilibrium
Vapor Pressure
- Partial pressure of liquids once equilbrium is established between gases and liquids
- Book Definition: Gaseous molecules pressure form evap. liquid
Liquid-Vapor Equilibrium
Dynamic Equilbrium
- Rate of forward process(l–>g) = Rate of backward process(g–>l)
- Constant Pressure
Liquid-Vapor Equilibrium
When is Boiling Point?
- When Vapor Pressure is equal to External pressure
Phase Changes
Critical Point
- Temperature that gas cant become a liquid no matter the pressure
IMF Trends
How are physical characteristics affected by IMFs?(only writing abt. high)
BP, VP, Viscocity, ST, Cohesive Forces
- Higher BP
- Lower VP
- Higher viscocity
- Higher ST
- High Cohesive Forces
Hydrogen Bonding
Salicylic Acid
- H-Bonding within molecule
Chromatography Lab
Rf
solute Distance/ Solvent Distance
VP Curves
Equation
- ln(Pvap1, T1/Pvap2, T2)=(∆Hvap/R)((1/T2)-(1/T1))
Alloys
Definition
- Solid Soln consisting of 2+ metals or metals with 1 + nm
Covalent Network Solids
Definition
- Network of covalently-bonded atoms into 2D and 3D network, holding it firmly together
Covalent Network Solids
Allotropes
- Elements exist in 2 diff formes in same physical state
- Ex) diamond and graphite for carbon
Semiconductors
Definitions
- Elements that are normally not conductors but are at high Temperatures or when coombined with other elements
Semicoductors
N-type
- Have an extra electron from bonding which can be used to create a voltage
- Donor Impurities
Semiconductors
P-type
- Have 1 less electron which creates “positive holes” that constatnly shift and allow current to flow through holes
- Acceptor Impurities
Physical Properties of Solns
Solvents
- determine soln’s state of matter
- usually majority component
Physical Properties of Solns
Solutes
- Substance dissolbed/dispersed in the solvent
Physical Properties of Solns
Solution Concentration
- Amnt of solute/ amount of solvent/soln
Physical Properties of Solns
Molality(m)
- moles of solute/ kg of solvent
- varies with mass of solvent and is independent of temperature
Physical Properties of Solns
Enthalpy of Soln
- Combination of Heat required breaking IMFs of solute and solvent plus the heat released for letting them mix
Physical Property of Solutions
Non-Ideal Solutions
- Not additive solutions(adding two solutions doesn’t result in a solutions with both that is not equal than combined amount: Ex) 50mL +50mL≠100mL)
- Happens due to unequal IMFS
- example of Ideal Mixture = Benzene and Methylbenzene
Physical Properties of Solutions
How Heat of Solution impacts ideality
- If = 0, Ideal
- If < 0, stronger solute-solvent forces; exothermic
- If > 0, weaker solute-solvent forces; endothermic
Formation of a Saturated Solution
What is a Saturated Solution
- Maximum amount of solid or gas allowed in a liquid with constant Temperature
Formation of Saturated Solution
How temperature affects saturation
- Increased ==> Increased in solids
- Opposite in gases
Formation of Saturated Solution
Henry’s Law
- Increased Solubility = Increased Pressure
- s = P * k
Formation of Saturated Solution
K in Henry’s Law
- Units: mg[gas]/100g[H2O]/atm
Colligative vs Noncolligative Properties
What are Colligative Properties?
- Physical Properties that depends only on concentration of solute particles, not their identity
- Decreased solvent vapor pressure, Freezing Point Depression, Boiling Point Elevation
Colligative vs Noncolligative Properties
Examples of Noncolligative Properties
- Color, odor, etc.
Volatile Solvents
What if solute is non-volatile?
- Lower solvent volatility because less on surface
- Raoult’s Law: Vapor Psolv = Xsolv ·P°solv
Volatile Solvents
What if solute is volatile?
- Have to consider both Vapor Pressures
- Pressure[Tot] = P[solvent A] + P[solvent B]
= (XsolvA · P°solvA) + (XsolvB · P°solvB)
Fractional Distillation
How does Fractional Distillation work?
- Boil 2 liquids
- Lower Boiling Point will boil out
- Rise to the condenser
- distillate
* Example: Water(50mL) + Ethanol(50mL) = mixture (< 100mL)- Distillation = 50 mL each again
Chemical Kinetics
What is it?
How fast rxns take place, facts that affect rates, and mechanisms
Chemical Kinetics
Factors affecting Kinetics
- Concentration
- Temp
- Surface
- Catalyst
Chemical Kinetics
what does Rate of Rxn equal?
-(1/a)(Rate of Reactant A) = -(1/b)(Rate of Reactant B) = (1/c)(Rate of Reactant C) = (1/d)(Rate of Reactant D)
Rate Law
What does Rate Law equal?
= k[A]^m[B]^n
* for aA + bB –> cC + dD
* m≠a and n≠b
* m = order of rxn wrt A
* n = order of rxn wrt B
Rate Law
Overall Order of Rxn
m+n
Rate Law
K
- Proportionality constant
- rate constant
- function of T
Reaction Rate
Methods to monitor change in reactant/product concentration
- Change in color using spectrophotometer
- Change in Pressure with manometer
- Change in Electrical Conductance
Reaction rates
Zero Order
- Rxn Rate: r=k
- Integrated Rxn Rate: [A]t = -kt + [A]0
- Half Life: ([A]0)/2k
Reaction Rate
First Order
- Rxn Rate: r=k[A]
- Integrated Rxn Rate: ln[A]t= -kt + ln[A]0
- Half Life: .693/k
Reaction Rate
Second Order
- Reaction Rate: r=k[A]^2
- Integrated Reaction Rate: 1/[A]t = kt + 1/[A]0
- Half Life: 1/([A]0* k)
Activation Energy
What is it?
Energy barrier that prevents less energetic molecules from reacting
Separatesineffective and effective collisions wrt energy
Activation Energy
Area under Maxwell-Boltzmann
- Represents fraction of collisions that are effective with correct orientation
- A= e ^(-Ea/RT)
- R = 8.314 J/mol/k
- T = K
Activation Energy
Rate constant equation with Activation Energy
- k = A * e ^(-Ea/RT)
- A = frequency factor = constant of soln to find rate constant
- R = 8.314 J/mol/k
- T = K
Activation Energy
To compare K values at different temperatures…
ln(k1/k2) = Ea/R(1/(T1) - 1/(T2))
Reaction Mechanism
What is it?
- Sequence of steps(each step = elementary step) and sum of all steps
- In the ES, rxn order for each reactant = stoic coeff.
Reaction Mechanism
Rate determining step
- Slowest ES = Speed of overall rxn
Reaction Mechanism
How to determine plausible mechanism
- ES must sum up to overall rxn
- Rate-determining step must have same rate law as overall exp.aly-det. rate law
Reaction Mechanism
Intermediate
- Produced in ES and consumed in later ES
Reaction Mechanism
Rate determining step senarios
- If the 1st step slow: 1st = rate of rxn and rest fast
- If 2 + steps slow: Step right before slow step = equilibrium and slow step = RDS
Activation Energy - Catalyst
What do they do?
- Increases rate of rxn(faster rxn) by decreasing Ea
- Present at beginning and end of rxn
Activation Energy - Catalyst
RDS relation to Ea
Highest Ea = RDS
Equilibrium
Chemical Equilibrium
Occurs when opposing rxn proceeds at equal rates
* Concentrations dont change with time making rxn appear stopped
Equilibrium
What is K?
- Equilibrium Constant
- = [A]eq/[B]eq = Pressure of A eq/ Pressure of B eq
- At Constant Temperature
- K»_space;1(>10): Equilibrium favors product formation
- K «1( <.10): Equilibrium favors reactant formation
Equilibrium
Law of Mass Action for general rxn
- Kc = [C]^c * [D]^d/([A]^a * [B]^b)
- Kp same just with P instead of [ ]
Equilibrium
Rules
- Solids not considered
- Liquid water when in excess not considered
Equilbrium
Converting from Kc–>Kp
- Kp=Kc(RT)^∆n
- R = .08206
- delta n = moles of product gas - moles of reactant gas
Modifying Equilibrium Expressions
Types of Modification
- Reversing Equation: K’c = 1/Kc
- Multiplying Equation by x: K’c = Kc^x
- Adding 2 equations: K’c = Kc1 * Kc2
Rxn Quotient
What is it?
- Qc/ Qp
- Concentration ratio for Kc/Kp at non equilibrium conditions
- Not constant but allows us to predict direection of net change
Rxn Quotient
How it helps us predict
- Q > K ==> backward rxn favored
- Q < K ==> forward rxn favored
ICE Table
What are they?
- I: Initial [ ] or P
- C: Change over time
- E: When at Equilibrium
Le Chat’s principle
What is it?
- Predicts how eq’m restored
- System will react to stress
Le Chat’s Principle
Adding or Removing a Substance in rxn
- Adding: system will shift and increased rate of rxn that decreases [substance]
- Removing: system will shift and decrease rate of rxn that decreases [substance]
Le Chat’s Principle
Stress sys by changing T
- Exo:
- Increased T = Increased R and Decreased P
- Decreased T = Increased P and Decreased R
- Endo:
- Increased T = Increased P and Decreased R
- Decreased T = Increased R and Decreased P
Le Chat’s Principle
Change P or V of Sys
- As P increases or V decreases(decrease space)
- eq net shift to side with less number of moles of gas
- As P decreases or V increases(increase space)
- Shift to side with more moles of gas
- If number of moles reactant = number of moles product, then there is no shift
Le Chat’s Priniciple
Special Cases
- Partial Pressures of reacting changes does change with adding or removing inert gases
- In a rigid container: Total Pressure will increase but Partial Pressures don’t(no shift)
- Constant External Pressure[balloon/ moveable piston]
- Same as ∆Pressure
Le Chat’s Principle
Changes that will not cause Eq. Shift
- Adding Inert Gas to constant volume container
- Catalyst
- Pure solids or Liquids
pKw, pH, pOH
Equations
- pH= -log([H3O+])
- Also H+ = 10^-pH
- pOH= -log([OH-])
- OH- = 10^-pOH
- pKw = pH + pOH = -log([OH-] [H3O+])
- Ka * Kb = Kw
pH, pOH
How to decide concentration of H3O+ or OH-
- if in strong acid just that from the acid because self-ionization of water is negligible
Conjugate Base/Acid
Hydrolysis Rxns
- Acid - base rxns between ions(from salts) and H2O molecules
- May react with water in a/b rxn
Conjugate Base/Acid
pH vs H3O+ / OH- concentration
- 7: [H30+] = [OH-]
- <7: [H30+]
>
[OH-] - > 7: [H30+] < [OH-]
Conjugate Base/Acid
Determining Conjugate Base/Acid
- If acid, then find with extra electron (goes from donator to acceptor) ⇒conj base
- If base, then find with less electron (goes from acceptor to donator) ⇒ conj acid
Acid, Bases, and Acid-Base Equilibria
Acid
- Proton Donor
Acid, Bases, and Acid-Base Equilibria
Base
- Proton Acceptor
Acid, Bases, and Acid-Base Equilibria
Strong Acids
- HCl
- HBr
- HI
- HNO3
- H2SO4
- HCLO4
* Complete Ionization: →
Acid, Bases, and Acid-Base Equilibria
Weak Acids
- CH3COOH
- NH4+
* Partial Ionization: ⇌
Acid, Bases, and Acid-Base Equilibria
Strong Bases
- Group 1A and 2A with Hydroxides
- Complete Ionization: →
Acid, Bases, and Acid-Base Equilibria
Weak Base
- NH3
- Partial Ionization: ⇌
Acid, Bases, and Acid-Base Equilibria
Ka/ Kb
- Acid/Base Ionization Constant
Acid, Bases, and Acid-Base Equilibria
Relation bet a/b and conj a/b
- Stronger the original, weaker the conjugate and vice versa
- Favored in the direction = stronger to weaker
Acid, Bases, and Acid-Base Equilibria
Kw
- Ion product of H2O
- = [H3O+][OH-] = 1.0 * 10^-14 M
- both H3O+ and OH- have concentrations of 1.0 * 10^-7
Acid, Bases, and Acid-Base Equilibria
How to deal with weak Acid/ Base equilibria
- Use ICE Table
- If M(a/b)/K(a/b) > 100, then [A/B]≈ Eq. value
Acid, Bases, and Acid-Base Equilibria
Which ions hydrolyze
- Weak acids or bases hydrolyze appreciably
- Strong a/b form neutral solutions
Acid, Bases, and Acid-Base Equilibria
Relationship between weak and strong a/b
- Weak Acids and Strong Bases = basic
- Strong Acids and Weak Bases = acidic
- Weak a + b = any of them
Common Ion Effect
Common Ion Effect
ASK ABT THIS
- Supression of ionization of weak acids or weak bases by presence of common ion from a strong electrolyte
Buffer Solutions
Definition
Solution that changes pH only slightly when small amounts of strong acid or base added
* Usually contain: weak acid/base with salt
Buffer Solutions
Buffer Rules
- ratio of [conjugate base/ acid] / [weak acid/ base] between .10 and 10
- both [conjugate base/ acid] and [weak acid/ base] exceed Ka by factor of 100+
Buffer Solutions
Henderson–Hasselbalch equation
pH = pKa + log([conj base]/ [weak acid])
Buffer Solutions
Heylman equation
pOH = pKb + log([conj acid]/ [weak base])
Buffer Solutions
Buffer Action
- best buffer is when [conj acid / base] = [weak base / acid] → best buffer!
Buffer Solutions
Effective Buffer Range
- Approximately when pH = pKa ± 1 pH-unit
Acid-Base Titrations
Analyte
- solution of unknown concetration
Acid-Base Titrations
Titrant
Solution with known concentration
Acid-Base Titrations
Equivalence point
AKA Stoichiometric pt
- # of moles of H3O+ = # of moles of OH-
Indicators
What are they
A weak organic acid that has a different color than conjugate base
Indicators
Relation bet. [HIn] and [In-]
- equal means intermediate color
- [In-]/[HIn] >10: solution will be color of In-
- [In-]/[HIn] < .10: solution will be color of HIn
Indicators
Endpoint
- Point where indicator changes color
Indicators
Equation
- Ka/[H3O+] = [In-]/[HIn]