CHEM Flashcards
When Cations are formed (loss of electrons) how does the configuration change?
Looses outermost (highest n, lowest nrg) electrons first.
-Could result in anoamlous configurations
Isoelectronic
Same electron configuration
Non Metal Characteristics
Poor Conductors
Non-Malleable and Brittle
Low BP and MP
Electronegativity
Attract electrons in covalent bond
Up and Right
Effective Nuclear Charge Zeff
To the right (and down)
-The effect of protons pulling VE in
-Increases with atomic number and decreases with shells, going down
Atomic Radis
Distance from the nucleus to the outermost electrons, those who want cat ion give up easy cuz not close to nucelus
Down and Left
Lattice Energy
The energy required to break up an ionic bond
-Increases with charge and closeness
Ionization Energy
Minimum energy to remove an electron from a neutral gas atom
-Up and Right
The IE is always the highest when
Trying to remove a electron from a Nobel as configuration
The second IE is always greater than first because?
IE is removing a negative charge. Once done it becomes a positive cation, and now you are trying to remove a negative away from a positive.
Gets harder everytime especially once at natural state
Electron Affinity
Energy released for an electrion is added to neutral gaseous atom
-How much the atom wants a electron
-Up and Right
First EA is endothermic or exothermic
Exothermic, natural the electron is attract to Zeff
EA Neg
Second EA is endothermic or exothermic
Endothermic because next electron has to overcome electrostatic repulsions.
EA positive
What is the relationship between mass/momentum and wavelength
Inverse
Heisenburg Uncertainity Principle
Exact position and momentum cannot be measured simultaneously
What function is used for the photoelectric effect?
Work Function
-Minimum energy to release a photon
Ek=Elight-W
Metallic Character increases
Down and Left
Empirical Formula
Smallest set of whole numbers that describe ratio of elements in a molecule
When a balanced equation only contains 1:1 ratio the limiting reagent is?
The one with the least amount of initial moles
Cation with a decreased charge have suffix
“ous”
Cation with a increased charged have suffix
“ic”
Polyatomic ions with multiple O2 for less amount of O2 have suffix?
“ite”
Polyatomic ions with multiple O2 for more amount of O2 have suffix?
“ate”
Increased charge on O2 containing polyatomic ions prefix?
“per”
Decreased charge for O2 containing polyatomic ions prefix?
“Hypo
Binary Acid Naming (H + Nonmetal)
Prefix= Hydro
Suffix = ic
Oxyacids Naming More Oxygen suffix
“ic”
Oxyacids Naming less Oxygen suffix
“ous”
Bond Order
How many bonds in a covalent bond
Sigma Bonds are located/formed?
head on overlap of orbitals along the axis between atoms
Pie Bonds are Formed?
Side-on overlap or parallel p orbitals
Single bonds have ___ sigma and ____pie
1 sigma
Double bonds have ___ sigma and ____pie
1 sigma and 1 pie
(1 supper, 1 dessert)
Triple bonds have ___ sigma and ____pie
1sigma and 2 pie
(1 supper, 2 desserts)
T/F Bonds are stable and decrease PE of system
True
Does a higher bond order mean higher or lower strength?
Higher Bond Order
Increased Bond Strength
Increased Energy to Break Bond
Decreased PE
Decreased bond length (triple –> Double –>Single) means stronger or weaker?
Stronger
Double Bonds can/or cannot rotate?
Cannot,
Two separate molecules even though same formula, ISOMERS
Single bonds can/or cannot rotate?
Can,
Same molecule if same forula
Sigma bonds are weaker or stronger than Pie
Stronger, ON OWN: but more pie bonds (double or triple) are stronger and more energy to break
The central atom is a structure is usally what?
Most EN
(usually carbon)
Halogens are usually terminal
What are the 3 exceptions to the octet rule
Incomplete Valence
Expanded Valence
Odd Electron Species
Incomplete Valence
Some atoms do not always need a full octet when forming a complete set of covalent bonds
Expanded Valences
Some atoms can accommodate more than a full octet when forming a complete set of covalent bonds
(P and Sulpher)
How many bonds can P have?
3-5
How many bonds can S have?
2-6
Odd Electron Species
Some molecules have an odd number of electrons. This makes it impossible for all their atoms to satisfy the octet rule and leads to unpaired electrons
A species with at least one unpaired electron is called a radical.
A species with at least one unpaired electron is called
A Radical
What is a Oxyacid
Hydrogen, Nonmetal and Oxygen
Hydrogen is directly attached to oxygen not a central atom
Resonance structures must have these two things:
1)Same Connectivity
2)Same Overall Charge
Major Resonance Structures have these 4 qualifications:
1)Full Octet
2)Minimum number of FC
3)Negative FC on electronic atom
4)Minimum separation between opposite FCs (stabilizes either)
Linear Angle
180 (360/2)
(2 attached)
Trigonal Planar Angle and attachement
120 (360/3)
(3 attached)
Tetrahedral Angle and attachement
109.5
(4 Attached)
Trig Bipyramidal Angle and attachement
90 and 120
(5A ttached)
Trigonal Planar + Linear
Octahedral Angle and attachment
90
(6 things attached)
3Linear
sp number of groups
2
SP2 Number of groups
3
SP3 Number of groups
4
SP4 number of groups
5
SP5 Number of groups
6
Nitrogen/Oxygen attached to Oxygen that could be double bonded by resonance is what hybridizaton
SP2/ LOOKS SP3
If a atom has a choice between SP3 and SP2 is chooses?
SP2
Trig planar: SP2 with one lone pair molecular geomtery
bent
Tetrahedral: SP3 with one lone pair molecular geometry
trig. pyramidal
Tetrahedral: SP3 with two lone pairs molecular geometry
bent
lone pairs in molecular result in what to bond angles, Increased repulsion
Decreased bond angles
What is Huckles Rule
All aromatic compounds must have odd number of pie bonds
2,6,10, 14.. (up by 4) pie electrons (1 pie bond = 2 pie electrons)
4n + 2Pie Electrons
Aromatic compounds must be ____ hybridized
SP2
Unsat versus Sat for packing
Sat.
Unsat = Pie bonds= rigid, and cis is even worse (Can’t tangle)
Sat= Sigma bonds and no cis and trans so it can tangle (take more to freeze when tangled)
What is Chirality
Any object that cannot be superimposable on its mirror image
Chiral centers have four different atoms or groups attached
D-Glucose
GUN
O ontop
Oh R
OH left GUN
OH R
OH R
OH R
CH2OH on Bottom
Constitutional Isomer
Same structure (ATOMS) different connectivity
Steroisomer
Same atomic connectivity but a different arrangement in space.
Conformational Isomer
They have the same molecular formula and connectivity, but their structure differs by the rotation of their carbon-carbon single bonds.
NEWMAN PROJECTIONS
What is the most stable Newman projection configuration?
ANTI: Staggered
LOW TEMP.
gauche are also staggered but carbon groups are closer not exactly 180 apart
What is the least stable Newman Projection configuration?
Eclipse
Overlappig especially when the carbon groups are
Z Priority
High Priority groups same side
E Priority
High-priority groups on opposite side
Enatiomers`
A pair of molecules that have the same connectivity but the opposite configuration at every chiral center
-Non -super impose mirror images
-Mirror image but cannot be placed on top of another
How do enatiomers act in plan polarized light?
They have the same properties
BUT ROTATE Opposite in Plane polarized light; but equal in quantity
5 Characteristics of Enatiomers
1)Opposite stereochemistry at all chiral centers
2)Identical physical properties
3)React identically in most enviro
4)React differently in a chiral envrio
5)Rotate opposite in plane-polarized light
SEE BEST OF FISCHER
R absolute stereochemistry is what direction?
Clockwise
S absolute stereochemistry is what direction?
Counter Clock
Absolute configuration when H is in not front (SIDES OF FISCHER)
Flip the R/S
Absolute configuration when H is in not front (Top and Bottom of Fischer)
Switch both sides and calculate
Dextorotatory (+) Rotates plane polarized light what direction?
Right Clockwise
Levorotatory (-) Rotates plane polarized light what direction?
Left CC
Racemic Mixtures
50% R
50%S
A equal mixture of both the R and S Enatiomer
What enantiomer do humans produce naturally
S
Racemic Mixture effect plane polarize light how
No net rotation of plane polarized light
How are racemic mixture seperated: Resolution of Enatiomers and Chemotology
Enantiomers react with another chiral molecule to produce diasteromic salts
ENATIOMERS CAN ALSO BE SEPERATED BY CHEMOTOLOGY
What are Diasteriomers
Stereoisomers that are not mirror images
-At least one different stereocenter and at least one same stereocenter
Opposite formate (L/R) chiral centers from each other in Fischer projection
What is the max number of stereoisomers for a molecule
2n
n= number of chiral centers
Meso Compound Requirements x2
1)Minimum 2 chiral centers
2)But achiral (have internal plane of symmetry)
Meso compounds in fischer projects cut what way for internal plane?
Horizontal (Hamburger)
Meso compounds do what to plane polarized light?
Do not rotate as the chiral centers cancer each other out
T or F Diasteromers have different physical properties
True
This means that they can be separated by:
Chromatography (polarity)
Distillation (BP)
Extraction (Solubility)
Thin Layer Chromatography is used for?
Polarity
Gas Chromatography is used for?
Boiling Pts
Size-Exclusion Chromatography is used for?
Size
Affinity Chromatography is used for?
Affinity
(antibody interaction, receptor-ligand interaction)
What are stereospecific reactions?
Reactions are those that only create one kind of enantiomer
PERFECT
What are stereoselective reactions?
Reactions favour one type of enantiomer but still have some amount of the other
LOOSE
Resolution x3 steps
When the extraction technique separates enantiomers (racemic or other ratio), it is called a resolution.
Enantiomers containing reactive functional groups (acidic or basic site) will react with optically pure compounds (all + or -) to make 2 diastereomers (diastereomeric salts)
Diastereomers can be separated via crystalization (one crystalizes and the other remains soluble)
To restore enantiomer: react the diastereomer salt with something to restore the functional group: Washing with an acid or base too cleave the restoring agent
Extraction
Liquid-liquid extraction is the process of separation based on the differing solubilities of compounds in different aqueous and organic solvents
REMEBER LIKE DISOLVES LIKE: will tell you what layer the desired molecule will be
How does extraction work
Separatory funnel filled with organic solvent (usually non-polar) containing some mixture of organic compounds to seperate
An Aq solvent is added (acidic, basic or neutral) and mixed
Two phases then allowed to seperate, aq phase is denser and drains
Organic Layer of a Liquid-Liquid Extraction will contain?
Non-Polar Molecules,
Aq Layer of a Liquid-Liquid Extraction will contain?
Polar Molecules
Thin Layer Chromatography TLC
Separates components of a mixtures of compounds by exploiting each compounds differing affinities for the polar STATIONARY HASE and their solubility in the less polar MOBILE PHASE
Stationary Phase
Species stuck to the rigid plate
Mobile Phase
Solvent which travels up the plate
More polar compounds in TLC
More time it will spend adsorbed on the polar coating and slower it will move up plate
Less polar compounds in TLC
Spend more time dissolved in relatively non polar mobile phase and will up the plate faser
How many stationary phase and are they polar or non-polar
2
Polar, More polar than any solvent you use as a mobile phase
Changing the polarity of the mobile phase will do what
Change the distance each component travels (increasing = increases, proptional relationship)
-Not change elution order
How to compare samples between trials of TLC
Retention Factors
Rf= Distance compound (product) travelled/Distance traveled by solvent (reactant)
Left= Reactant
Right= Product
AT TOP and END of RXN, there should be nothing right top as it is turned reactantr
Paper Chromatography
Uses paper as the stationary stage
Compounds solubility in the mobile phase determines its retention factor Rf
Anticipate: Highly soluble compounds travel farther than lower soluble in the solvent system used as a mobile phase
Ideal Gas Equation
pv=NRT
The average kinetic energy of a gas is proportional to what?
Temperature
How to measure atm pressure using a barometer?
Patm = pgh
-p = density of mecury
-g =gravity
-h= height of mercury
How to measure pressure of a unknown gas using a manometer?
Psam = Patm + pgh
-p atm must be known
-p is density of gas
-h is the height of liquid above point B (for sample) or A (for atm)
Patm =Psam +pgh
How many kpa is 1 atm of pressure
101kpa
you are 1 atm
lol kpa
How many bar is 1 atm of pressure?
1 bar
How many torr/mmHg is 1 atm of pressure?
760 Torr
760 mmHg
At STP 1 MOL of any idea gas is how many L
22.4 L
WHAT Temp is STP
274.15 k, 0C
1 ATM
What is absolute zero in K and C
0K
-273 C
When temperature increases what happens to pressure and volume?
Volume Increases
Pressure Decreases
Proportional Relationship
What is the relationship btwn volume and pressure
Inverse
What is the partial pressure of a gas?
The partial pressure of a gas is the same pressure it would exert if it were alone in the container.
Partial pressure is proptional to?
Mole fraction
Number moles of gas A /
total moles of gas in container
Calculation of partial pressure of a gas?
Pa = Xa x P total
Mole fraction x total pressure
True or False all partial pressures add up to the total pressure of the gas in a container?
T
For an ideal gas pv/NRT will equal what?
1 atm at any external pressure or temp.
A gas is ideal at increased or decreased pressure?
Decreased
Why in real gases will PV/nrt deviate from 1 atm
PV is greater than NRT
When P increases, V doesn’t decrease proportionally (more resistance to decreases, as gas molecules take up space)
-Therefore, it is ideal to have decreased pressure.
When is a real gas PV/NRT (compressaibility) greater than 1?
Positive deviation is due to volume (molecular volume)
When is a real gas PV/NRT (compressaibility) less than 1?
Negative deviation due to intermolecular forces
At low/moderate pressures, the PV real value will be less or more than the PV ideal?
Less, as the volume as less volume than predicted by ideal gas law
At high pressures, the PV real values will be less or more than the PV ideal?
Greater, as the volume is greater than predicted by gas law (restriction to compress)
How does temperature effect a real gas compared to ideal?
The higher the temperature the closer to ideal as there is less intermolecular force interaction
What is the vanderwalls equation used for?
Un ideal gases
n2(a)/V2 part of vanderwalls accounts for
Attraction (interaction/intermolecular forces) between molecules
nb terms in vanderwalls accounts for
Bulkiness (volume of particles)
How are reaction rates expressed (what unit)?
M/s
How to find the reaction rate?
Take the amount of moles and multiple it by stoich ratio
Reaction rate decreases with what?
Concentration of reactants
T or F: Orders of rate laws can be determined by stoich ratios?
False Must be determined experimentally
T or F: Rate law uses both products and reactants?
False just reactants
The sum of all the orders is equivalent to what?
overall order of the reaction
Rate law equation
R= k[A]^x[B]^x
where x is the orders of each corresponding rectant
How to calculate the rate law and rate constant of a reaction?
1) Find orders:
-For each one where one reactant is constant and the other is changing between 2 trials
-(X1/X2)^m = R1/R2 (solve for m)
2) Rearrange R=k[A]^x[B]^x to solve for K
Use randome trial
Calculates the units of the rate constant (K)
nth-order
M^(n-1) x S^-1
Oth order reaction is what?
Slope = -K
Concentration vs time
Linear down
ntegrated: Linear neg slope down
1st order reaction is what?
Slope = -k
ln concentration vs. time
Curve down not as steep
Integrated: Linear neg slope down
2nd order reaction is what?
Slope = k
1/concentration vs. time
Curve steep slope down
Integrated: Linear Positive slope up
Difference between rate laws and integrated rate laws
Rate laws predict the rate of the reaction from initial concentrations of reactants.
Integrated rate laws predict the reactant (or product) concentration as a function of time.
What 3 factors is the rate constant dependant according to the Arrhenius Equation?
p: fraction of collisions with proper alignments
z: collision frequency
f: fraction of collisions with sufficient kinetic energy to overcome the activation energy of reaction
What 3 things can effect reaction rates?
1) Reactant concentrations
-increases with increase concentration
2)Temperature
-increases the speed of molecules and collision frequency as temp increases
3)Catalysts
-Raise the reaction rate without being permanently consumed
In Endothermic rxn, the energy of the products is greater or less of the reactants?
Greater than the reactants therefore require alot to overcome energy of activation
In exothermic rxn, the energy of the products is greater or less of the reactants?
Less than the reactants
therefore give off energy, and do not need to overcome energy of activation.
true or false Catalysts are used and then formed.
true
true or false intermediates are formed and then used
true
What are characteristics or termolecular reactions?
slow or don’t happen
What is molecularity?
The number of molecules involved in a given elementary rxn
When can stoichemetric coeffients be used to determine order?
Elementary reactions
(broken down into it steps, to be sure)
-Unimolecular (dissociations) squared
-Bimolecular
-Trimolecular
Equilibrium constant can only be affected by what?
Temperature
T or F equilibrium constant includes all states
F, only aq or g
If the co-efficients of a balanced equilibrium reaction are multipled by a given factors the equilibrium constant will be?
Taken to the power of that factor
If the co-efficients of a balanced equilibrium reaction are divided by a given factors the equilibrium constant will be?
Taken to the root of that given factor.
When multiple equilibrium reactions are combined, the equilibrium constants of the reactions are?
Multiplied together.
What is the reaction quotient (Q)?
Expression that combines all the instantaneous concentrations or partial pressures in a given system
Gives the rxn current loco at a pt in time.
How is Q (reactin quotient) calculated?
Same as equilibroum constant (Kc) Products over reactants using stoich co-efficienrts_
Comparing Q to K tells u what?
Direction of the reaction to reach equilibrium
If Q is less than K
System is moving towards equilibrium in the forward directions
Q must increase
If Q is greater than K
System is moving towards equilibrium in the reverse direction
Q must decrease
Increasing volume/decreasing pressure shifts the equilibrium how?
To the one with MORE chemicals
Make more moles cuz space
Decreasing volume/decreasing pressure shifts the equilibrium how?
To the one with LESS chemicals
Make less moles cuz less space
Exothermic reactions increasing temp, what happens to equilibrium constant K?
Decreases (shifts away from heat) reverse
Exothermic reactions decreasing temp, what happens to equilibrium constant K?
Increases (shifts towards heat) forward
Endothermic reactions increasing temp, what happens to equilibrium constant K?
Increases (shift away from heat)
Forward
Endothermic reactions decreasing temp, what happens to equilibrium constant K?
Decreases (shifts towards heat) reverse
What is the general rule for solubility?
Partners of strong acids/bases are soluble
What is a Arrhenius acid?
Produces H+ ions in aq
What is a Arrhenius base?
Produces OH ions in aq
What is always formed in a neutralization rxn?
Salt and Water
Bronstead Lowry Acid
Species that produce H+
Bronstead Lowry Base
Species that accepts H+
Lewis Base
Species that acts as an electron-pair donor
Nucleophile
Bases Loath Electrons
Lewis Acid
Species that acts as an electron pair acceptor
Electrophiles
ACIDS LOVE ELECTRONS
7 Strong Acids
HCl
HBR
HI
H2SO4
HNO3
HClO3
HClO4
8 Strong Bases
NaOH
KOH
CaO
Na2O
H-
Ca(OH)2
Ba(OH)2
Sr(OH)2
First two columns bound to OH
Ka and Kb values are used for strong or weak acids or bases
Weak
p mean what
-log (x)
pH + pOH equals what
14
What is Kw
Water equilibrium constant
Keq = [H3O+][OH-]
Increasing the teperature does what to pH
Decreases
6 is neutral instead of 7 @ greater the 25C
What happens if the concentration of the strong acid is less than 1x10^-7 M (less than the concentration of H+ already in water)
This applies to strong to bases too (less than concentration of OH- already in water)
Negligible
We need to take the autoionization of water into account>?
Pick the answer close to 7 on the right side of neutral
True or False a really strong acid can make a weak acid behave like a base
True
Same for bases
(weaker than water)
A weak acid reacts with water and gains or looses H+
Looses H+ (becomes conjigate base, more neg)
H3O Produce
weak acid = acid
H2O = Base
A weak base reacts with water and gains or looses H+
Gains H+ (Becomes cong acid, more poistive)
OH- produce
Weak Base =Base
H20 = acid
What is the relationship bwtn Ka and Kb?
Ka x Kb = 14
The Ka of weak acid, Kb is the conjuygate base
If a Ka of a weak acid is greater than 10^-7 the conjugate base will stronger or weaker?
Weaker
If the Ka of a weak acid is less than 10^-7 the conjugate base will be stronger or weaker?
Stronger
The conjugae to a strong acid or base will be?
VERY WEAK
When Ka increases what happens to Pka
Decreases
Ka gets bigger = Stronger
PH= gets smaller (more acidic)
Ka/Kb from PKa/PKb
Kb/Ka = 10^-pka/pkb
Pka/PkB from Ka/KB
pkb/pka = -log (ka/kb)
Ka to Kb
Kb =Kw/Ka
Ka =Kw/Kb
Pka to Pkb
Pka =Pkw (14) -Pkb
Pkb = Pkw (14) -Pka
When are ice tables used?
When calculating the pH for Aq solutions of weak acids and bases
Ice tables how to use?
1) calculate initial molarity C=n/V
2)Make sure rxn balanced
3)make table to find Ka expression
4) Ka expression
Ka= x2/ M-x
5)Removes -x
6) Add in Ka values (given)
7) Solve for x
(usually will have to increase mantas and decrease exponent)
8) Solve for pH
Strong Acid + Weak base produce what
Acidic Salt
Cation is acidic and anion is neutral
String base + Weak acid produces what
Basic Salt
Cation is neutral and anion is basic
A stronger acid produces a more or less stable base?
More stable conj. base
What determines the strength of a an acid
ARI
Atomic Radius
Resonance
Induction
A stronger acid will have the most ____ atom, and the negative charge will be on that atom in the conjugate base
Electronegative, holds the neg charge better.
Right and Down the PT
Better the closer to the subituant is
What are inductive effects and how to the relate to stability?
They spread out charge
The more electroneg atoms the more spread out and mmore stable
In a AA the carbonyl group pka is what
2
In a AA the amino group pka is what
9
For a polyprotic acid the pH of the solution is equal to what?
[H3O+] produced from only the first step (rest are negligible)
-Find the pH from the first step.
Pka of D and Isoeletric (when neutral)
4, A: Two smallest
Triprotic Amino Acids are?
Charged
Pka of E and Isolectric (when Neutral)
4, A: Two smallest
Pka of H and Isolectric (when Neutral)
6, B: Two Largest
Pka of C and Isolectric (when Neutral)
8, A: Two Smallest
Pka of Y and Isolectric (when Neutral)
10, A: Two Smallest
Pka of K and Isolectric (when Neutral)
10, B: Two Largest
Pka of R and Isolectric (when Neutral)
12, B: Two largest
What is a titration?
Adding small amounts of a strong acid or base to determine the unknown solution of a strong acid or base
What is the equivalance /Stocihemtric pt?
When all the analyte has been reacted with titrant
For a SA/SB curve = pH 7
How to know when the equivalence pt occurs?
Using a indicator (weak acid or base) changes colour at the end point
What is the end point of a titration curve?
When the indicator changes colour
When does a buffer region occur in a titration?
Titration with a weak acid and strong base.
Equal amount of weak acid and and conj base
Number of moles of weak acid is half of the amount of moles of strong base added.
pH of the solution is pKa of weak acid
How to decide what indicator to use?
The one that colour change pKa is during the known equivalance pt (when all analyte has bene reacted with titrant)
What is the mid point
half-equivalence point
pKa of the weak acid
The buffer region exists in range?
PKa +/- 1 pH unit of 1/2 equivalance pt/mid point /pka of weak acid
What is the Henderson Hassalbach Equation?
pH = pKa + log (Conj. Base/ Weak Acid)
For titrations with weak acids and strong bases
Calculates the pH of a buffer solution.
How to find how many ions/molecules in a a given amount of moles?
Multiply by avogaardros number 6.02x1023
What is a buffer made of?
A weak acid/base and its conjugate in equal concentrations
Why is water not inlcuded in equibirum equations
Because it is constant throughout the entire rxn
What is thermodynamics?
The study of the flow of energy during the chemical process
Extensive Property
Depends on the amount of matter present in a system
-Mass, Volume, Entropy, Enthalpy, Internal Energy, Free Enegry
Intensive Property
It does NOT depend on the matter present in a system
-Temp. Density, Melting Pt
Thermodynamics: process
Net difference between final and initial states
Thermodynamics: Path
Complete series of steps taken to get from initial to final positions
What is temperature?
Measure of average kinetic energy per system
Zeroth Law of Thermodynamics
When 2 or more objects are brought together, they will exchange energy until they are at the equiibirum (same temperature.)
State Functions
Properties that depend on only final and initial states and no the path taken
HAVE CAPITALS
Path Function
Are properties of a system that depend on the way in which the change is carried out
LOWER CASE
4 Types of Internal Energy Lowest to Highest Energy
1)Translational Energy
2)Rotational Energy
3)Vibrational Energy
4)Electronic Energy
What are the two ways to transfer energy
1)Heat
2)Work
3 Ways heat is transfered?
1)Conduction (touch)
2)Convention (within fluid)
3)Radiation (EM waves)
Free Work is
Positive
(work done to you)
Doing Work is
Negative
(work done BY you)
What is internal energy
The sum of the kinetic and and potential energy in a system
First Law of Thermodynamics
Total energy of the system and surroundings is constant
Change of energy in a system must equal the sum of heat exchanged to/from system and work done on/by the system
2 ways to transfer internal energy
1)Heat
2)Work
Endothermic
ENEGRY GAINED
Heat is absorbed by System
-q is greater than 0
Work is done on the system
-W is greater than 0
Exothermic
ENERGY LOST
Heat is given off from system
-q is less than 0
Work is done BY system
-W is less than 0
Enthalpy
Total energy transferred during a chemical process, including the change in internal energy and any energy (work) required to make room within surroundings for the products of the reaction
Joules
Hess’s Law
The total enthalpy of an overall reaction is equal to the sum of enthalpy changes for he indvidual steps
What are the 2 rules of Hess’s Law
1)If the stoichiometric co-efficient of a reaction step is multiplied or divided by a factor, then the change in enthalpy for the same step must be multiplied or divided by that same factor
2)If a reaction step is reversed than the sign of the change in enthalpy must also be reversed
What is the standard enthalpy of formation?
Enthalpy change that occurs during the formation of ONE mole of a substance from PURE ELEMENTS in their STANDARD STATES
What is the standard enthalpy of formation of a pure element in its standard state
0
Entropy (S)
State function that provides a quantitative measure of the NUMBER OF MICROSTATES
Increased amount of microstates results in what to entropy
Positive
Entropy units
J/K
5 Key pts of Entropy
1)Entropy Gas»_space; Liquids> Solids
2)Higher Entropy
3)Large volume >small volume
4)Large molecule > Small Molecule
5)HIGHER MOLES GAS > LOWER MOLES GAS
During phase change what occurs to temperature?
Stays constant
What is the second law of thermo?
Any spontaneous process increases the entropy of the universe
In a reversible process the entropy of the universe equals
0
In a irreversible process (spont.) the entropy of the unviverse equals?
Greater than 0
What is the third law of thermodynamics?
At 0K, particles in a perfectly ordered crystal have no thermal energy, no motion, and no disorder
Reversible versus irresiversable processes in terms of entropy
Reversible = Make equilibrium
Irreversible = Spontaneous,
When Gibbs energy is negative, the reaction is spot. or not?
Spont. in direction written
When Gibbs energy is pos. The reaction is pos. or not?
Non. Spont. in direction written
(spont. in opposite direvction)
Spont./EXO Products higher or lower than reactants
Lower
Gibbs Negative
Non.Spon./Endo. Products higher or lower than reactants
Higher
Gibbs Positive
Gibbs free energy depends on what?
Change in enthalpy and entropy at constant temp.
Non spont reactions can become spont by doing what?
Changing temperature
Temp. is positive but if you change in high enough so entropy is higher than enthakpy
Gibbs in a phase change is equal to what?
0
During phase changes what breaks?
INTERmolecular Bond
Heat is absorbed in what phase changes?
Solid –> Liquid –> Gas
Heat is released in what phase changes?
Gas –> Liquid –> Solid
Supercritcial Point occurs at
High Temperature and High Pressure
Triple Point Occurs at
Low Temp. and Low P
Solid to Liquid
Melting
L to S
Freezing
S to G
Sublimation
G to S
Deposition
L to G
Vapour
G to L
Condenstation
What does the line for water between solid and liquid have a negative slope
Water (Ice) in solid is less dense than liquid water
As pressure increases the melting/freezing point decreases
Isobaric
Constant pressure
Heat of Fusion
Enthalpy change associated with melting
Heat of vapourization
Enthalpy associated with boiling
Heat of vapouration or Heat of Fusion greater
Heat of Vapourization
-More energy is required to change phse from liquid to gas than from solid to liquid
Heat Capacity
How difficult it is to change the material’s temperature
Change in temperature in a material depends on these 2 things
1)How much heat was added (q)
2)Heat Capacity (C)
Sensible Heat
Temperature changing
Latent Heat
Phase Change
(Temp. constant)
A longer latent heat period means what
More heat is required for phase change
What is a calorimeter
Device that measures the energy changes of a given process
Coffee Cup Calorimeter
Measures heat required to carry out a given process at CONSTANT PRESSURE
Heat is either absorbed or released by system and transfered or taken by surroundings
Temp. change of surroundings is measured
Bomb Calorimeter is always exo or end
Exothermic
Difference between coffee cup calorimeter and bomb
Bomb is constant volume
Coffee is constant pressure
Bomb Calorimeter is used to calculate?
Heats of Combustion Rxn
CCal must be known
For bond enthalpies ensure what?
Equation is BALANCED
Simple alcohols release more or less heat?
More Heat
Increased Enthalpy
What are electrophiles
Lewis Acids
Accept Electron pairs
3 key features of electrophiles
1)Electron withdrawing groups
-connected to EN atom
2) An incomplete octet: Boron
3)Carbocation: positively charged
Most common electrophile functional groups? x3
1) Aldehydes
2)Ketones
3)Carboxylic Acids and Derivitives
What are nucleophiles?
They donate electron pairs to electrophiles
2 structural features of nucelophiles
1)Presence of lone pair electrons
2)Presence of pie bond electrons (multiple bonds)
3)Negative Charge
Functional Groups that are nucelophiles?
1)Alcohols
2)Amines
SN2 reactions are how many steps?
1
Nucleophile attacks and LG leaves in the same step
When there is a chiral carbon in SN1 reactions, what do you need to be aware of?
R and S configuration
Racemic mixtures
What order kinetics do SN2 reaction show?
Second order
r=k(substrate)(Nu)
SN2 reactions are primarily used for what type of carbons
Methyl or Primary because least steric hinderance
SN2 reactions favour strong or weak nucleohiles?
Strong
Better nucleophiles are sterically hindered or not? or does it matter?
Not Sterically hindered
(needs to attack easy)
SN2 reactions occur in polar or polar aprotic solvents?
Polar Aprotic
(can’t form H-Bonds)
Polar Aprotic Solvents
Don’t contain Hydrogen attached to EN atoms
Polar Protic Solvents
Contain Hydrogen attached to EN atoms
SN2 favours what type of leaving groups?
Good LG
5 Good LG
1)Water
2)I-,Br-, Cl-
3)Acetate
4)-OTs
5)-OMs
Common Aprotic Solvents
1)Acetone
2)Ether
3)DMSO
4)DMF
5)THF
6)HMPA
A strong nucelophile is more or less stable?
Less Stable: More Reactive
ARIO determines what?
Stability of an atoms/base
SN1 rxn are how many steps and explain
2 step substitutions
1)LG leaves generate a carbocation intermediate
2)Nucleophile takes the empty P-Orbital
SN1 reactions are what order
First Order Kinetics
rate= k(substrate)
Relies on how fast the LG leaves
If a atom does not have the correct number of bonds what does it likely identify?
Wrong Number Bonds
The most important factors affect SN1 reactions affect the stability of what?
Create stability in the Carbocation
What carbons are the strongest electrophiles/substrates for Sn1 reactions?
Tertiary (3 groups off carbons)
-Yield the most stable carbocation on LG
SN2 prefer versus SN1 perfer for stability
SN2 prefer least stable
SN1 Prefer most stable
The role of the nucleophile for SN1 reactions?
Doesn’t matter cuz not rate limiting step
The role of the LG for SN1 Reactions?
Good LG is neccessary , depatrue is the RLS
What is a good LG
Required for both SN1 and SN2
-Leaves as a neutral molecule or a sable unreactive anion
-SOMETHING THAT WON’T ATTACK THE PRODUCT OF THE RXN
What solvent is favoured in SN1 rxns?
Polar Protic because they stabilize the carbocation intermediate
If you see a -OH group in solvent is often what type of reaction?
SN1
SN1 and rearrangements
Methyl groups or hydrogens will move to a more stable carbocation to make a SN1 reaction work
carbocation from 2 to 3
SN2 sterochemistry
Inverted relative configuration
Resonance adds to stability increasing what?
Primary, Secondary, Tertiary
Double bonds increase stability by resonance increase original by 1.5
-OH is a strong or weak LG
Weak LG
Therefore must be prontation of OH to make into H2O a strong LG
Good Leaving groups are _____conjugate bases and ____ nucelophules?
stable conjugate bases
and
poor nucleophiles
What are the 3 ways -OH can be made into a good LG
1)Protonated (made into H2o)
2)Tosylation (R-OTs)
3)Mesylate (R-OMs)
Ethers are reactive or not
Not
When ethers react they often do with what and how
Substitution reactions with HBr of HI
Any mineral attached to Hydrogen
True of False Ethers hydrogen bond
True
Why don’t ethers bind together
Creates a lower boiling pt then most alcs
Is a carbonyl group?
A functional group composed of carbon atoms and double-bonded oxygen atom
The carbon in carbonyl compounds has what hybridization?
SP2
What reactions do aldehydes and ketones undergo?
Nuceleophillic Addition
T or FNucelophillic addition forms racemic mixtures?
T cuz carbocation can attach to either
IF CHIRAL CENTER IS FORMED
What is the common carbon-carbon bond created by the nucelophilic addition reaction of aldehyde or ketone?
Cyanohidrin
N triple bond C attaches to aldehyde or ketone with a Hydrogen to remove negative charge on oxygen
What is oxidation?
When a carbon gains Oxygens and Looses Hydrogen
What is reduction
When a carbon looses Oxygen and Gains Hydrogen
When a primary alc is oxidized initially it becomes what?
Aldehyde
After a primary alc becomes a aldhyde what occurs using most reagents
Continues oxydation to become a carboxylic acid
What reagent stops is used to oxydize a primary alc to just a aldhyde
PCC
Most oxydizing agents are
a metal with lots of oxygen
Oxydation of secondary alc forms what
Ketones
Tollens reagents do what
Oxydize aldehyde to carboxylic acid even in presence of alc
Jones reagent do what
Oxydize primary alc all the way to carboxylic acid
The number of what determines the amount of oxidation rounds that can occur?
Amount of hydrogen attached to carbon beccause that is what O attaches to (to carbon)
What oxidating agents will oxidize a secondary alc
All but Tollens
Oxidation of a secondary alc can occur how many times?
Only Once
True or False Oxidation of tertiary alc is possible?
False, No hydrogen to loose
What reduces aldehydes and ketones?
NaBH4 (sodium borohydride) /Ethanol (EtOH)
+ an acid (H3O+) to yield primary and secondary alc
What are carboxylic acids and. esters reduced by?
LiAIH4 (Lithium Aluminium Hydride) /Et2O (Ether)
Reduction results in the removal of what
Double bonded O and replace with OH
When a ketone or aldyde reacts with a alc what does it form
1 alc: Hemiacetal or Hemiketal
2 alc: Acetal or Ketal
When a weak nucleophile (water) adds to a aldhyde or ketone what does it form
Hydrate
Nucelophillic additions to ketone or aldehyde work best with what
Acid Catakyst
Eliminations cause what to form
Double Bonds
What can be used as protecting groups and why
Ketals and Acetaks
Unreactive towards bases
Why do we use protecting groups
Because some reagents will oxidize or reduce something all the way and we may not want that
What are tautomers
Pair of easily converted constitutional isomers
Interconversion = Tautomerization
What are 2 common tautomers
Enol and Keto
For simple carbonyl compounds what tautomer is more common?
Keto
B-dicaronyl compounds what
tautomer is more common?
Enol Tautomer
Stabilized by Hydrogen bond
Tautomerization is best shown by
Shift of hydrogen atom and double bond
What are alpha hydrogens
Hydrogens attached to the alpha carbon
What is the alpha carbon
The one attached to the functional group
What Hydrogens on a molecule are acidic
Only the ones attached to alpha carbon
What are enolate anions
When hydrogen can be easily removed from carbon due to resonance stabilization
Alpha carbocations resulting enotate anion is possible in what
Ketones
Aldehydes
a-Carbon looses a hydrogen and the double bond from the functional group comes down to stabilize
What are the 2 ways a enolate anion can accept a proton
1)Accept in its carbocation form resulting in a ketone
2)Accept in its enolate form resulting in an enol
The enol form is chiral or achiral
achiral
The keto form is chiral or achiral
chiral
If a alpha carbon is chiral when alpha carbon are removed to form enolate carbon what happens
Forms a racemic mixture on return from enol to keto
enol versus ketone
Enol = Double bonds btwn and OH
Ketone= Double bond O and 2 H
True or False enolate anions can acts as a nucleophile and attack electrophile
true
Negative charge allows them to attack where the Hydrogen was
Beta-Catalyaed alpha subsitution
What is an adol reaction
Enolate ion of an aldehyde or ketone reacts with carbonyl group of an aldehyde or ketone
New carbon carbon bond form attaches the 2
OH and Double Bond O is produced
What is the best way to predict the products for adol reactions
Landmark (added onto new carbon)
New carbon is between:
OH and Double Bond O is produced
What occurs in adol condensation
Looses the OH molecule and gains a double bond between OH and double bond O w
When will a adol undergo dehyration?
1)Final step includes acid and heat
2)Final step includes a base and heat
What is nucelar magnetic resonance (NMR)
Structure of a molecule based on the different environments of certain atoms
Hydrogen Enviroments
Each peak represents a set of chemically equivalent hydrogen nuclei
-Distance away from fxnal group matters
On NMR there is a signal peak where
0ppm
Signals upfield (higher number) are what?
More e defiecent, heavily shielder
Close to Fxnal group
Signal fields downfield (lower number) are what?
Less e deficient, less shielder
Further from final group
What is peak splitting
Results in higher number of peaks than on its own, if neighbouring hydrogens are not equivilant
Yours is 1 + # of neighbouring (neigbouring is how many hydrogen come off each neighboruing carbon)
ONLY IF NEIGHBOUR IS DIFFERENT
Peak areas or intergral face is represented by
Number of chemically equivalent hydrogems
What is the index of hydrogen deficiency (IHD)
Degrees Unsat.
In NMR the number of peaks equal
The number of different H Groups
Hydrogen enviroments can be told be what in NMR
Number of peaks
Electron Polarization can be told what in NMR
Order of peaks(downfield to upfield)
Neigbouring Hydrogens can be tild by what in NMR
Number of peaks in each signal
Number of hydrogens can be told by what in NMR
Peak Areas
IR spectroscopy is used for
Uses EMR from infrared region,
-Bond vibrating at different frequencies when exposed
-Determine Fxnal Groups
Vibrations in IR spect are stronger when/increase frequency x2
1)Stronger Bond (T > D > S)
2)Lighter Elements
Alochol Vibration frequency
3300 cm-1
C-H
O-H
N-H
LIGHTER SO MORE VIBRATION
Carbonyl (C DB O) frequency
1725 cm-1
What is ultraviolet spectroscopy used for?
The enxtent of Pie comjugation
(alt. single and double bonds)
The higher (longer) the wavelength of max absorption in UV spect means what?
greater amount of conjugation
200-400nm
What is mass spect
Gives molecular weights and sometimes molecular formula
finds mass/charge ratio
Base Peak Mass Spect
Largest peak
Most common and stable cation
-plotted relative to base peak
Parent peak Mass Spect
Approx Molecular weight
The rest are isotopes
-Og mass of molecule before bombardment minus 1 electron
Size Exclusion Chromtology
Separates and compares particles by size
large travel less distance cuz don’t get stuck
small travel more distance cuz can get stuck in gel
What is Esterification?
Carboxylic Acid Converted into esters by SN2 or Fisher Esterification Reaction
5 Steps of a Nucleophilic Acyl Substitution
1)ID LG
2)ID NU
3)Break Bond to LG
4)Form bond to NU
5) Add or Subtract H+ so FC= O
What is a nucleoohilic acyl subituition
A nucleophilic addition plus a elimination
Carboxylic Acids and their derivatives often undergo what reaction
Nucleophil acyl subsitution
Rings that contain amide are called what
Lactam
What rings are most stable
5 and 6 membered rings
What are the 4 carboxylic acid derivitives
1)Acid Chloride
2)Anhydride
3)Ester
4)Amide
Acid chloride + Carboxylate produce what
Anhydride
Acid Chloride + Alc + Non-nucelophillic base produce
Ester
Acid Chloride + Amine produce
Amine
How are acid anhydrides produced?
2 Carboxylic acids + Heat
What is transesterification?
The process of reacting an ester with an alcohol to yield a new ester and alc.
(Interchange of R-Groups of Reactants)
What is sponification?
Hydrolysis of an ester in basic solution
How can amides be prepared?
By all acid derivitives
amine + carboxylic acid derivitive
To bring a carboxylic acid deritive back to a carboyxlic acid what needs to be done?
React derivitive with water
Primary amines react with aldhydes and ketones in the presence of an acid catalyst to yeild what?
Imines
Alcohols react with SOCl2 to produce what
alkyl chloride
(same with PCl5 and PCl3)
Oligosacchardies are complex or simple polysaccahrdies?
Neither
3-10 units
Open chain or linear forms of monosaccharides are classified as x2
1)Aldoses
2)Ketoses
What is the suffix of a carbohydrate?
-ose
The highest priority group on a fischer projecton is located where?
As close to the top as possible
-Most oxidized functional group
Most naturally occuring sugars are D or L
D
Enatiomers
Opposite at all Chiral Centers
Diastereomers
Some not different at chiral centers
Epimers
Only 1 Chiral Center is different
Aldehydes and Ketones react with alcohols to produce what
Hemiacetal
Hemiketal
-Nucelophillic addition
Axial Position
Above Ring or Below Ring
Equatorial Position
In the plane of ring
What is more stable pyroanose or furanose
Pyranose (6 membered ring)
comes from 6th (last carbon) Glucose
Furanose (5 Membered ring) Comes from 5th carbon
Fructose
What is a anomeric carbon
Only carbon with 2 oxygen groups attache dto iy
What is mutarotation
Occurs as the alpha and beta anomers interconvert
What is more stable being alpha (trans) both axial or being beta (cis) one axial and one equatorial
Beta One axial one equatorial
Equatorial is most stable
Anomers differ how
the highest priority in cis or trans
Acetals are formed from what
Aldehydes (2 alc)
Ketals are formed from what
Ketones (2 alcs)
In a hemicetal/ketal the carbon is bound to what
-OH and -OR
After one alc
In a acetal and ketal the carbon is bound to what
2-OR groups
after.2 alc
True or False Glycosides are in equilibrium between cyclic and open chain forms
False, they are locked in place in basic and neutral conditions
only acidic can they be brought back to free monosaccaride (hydrolysis , water and catalyst)
How to tell if a tollens test occured
Ag(s) produced
Aldehydes in open chain form of aldose canreact with what reagents to become a oxidized sugar
Tollens reagent
Benedicts Reagent
What are the 3 reducing sugars
1)Monosaccharides Aldoses (Open-chain or hemoacetals)
2)Monosaccharides Ketoses (if they can tautomerize into aldose)
3)Disaccarides or Oligiosaccahrides with hemiacetals or hemiketals (-OH on anomerical carbon)
Non Reducing Sugars are?
Acetals and Ketals
What is Tautomerization
Additon or removal of H
Amino acids are naturally occuring in R or S
S
The D or L AA are deterimined by what
Which side the NH2 (amino) group is on
-Flips with H
What AA is naturally occuring D or L
L and alpha
At what PH are non-charged AA neutral
pH=6
What are the two ways AA are formed?
Gabriel Synthesis (Potassium+Diethyl Ether)
Strecker Synthesis (Uses HCN)
What is Strecker Synthesis
CN attacks aldehyde , followed by an attack by H2O
Nitrogen removed and COOH formed
The formation of a peptide bond bwtn AA is what type of reaction?
Dehydration
The formation of a disulfide bond betwen cystines oxidizes or reduces it
Oxidizes
How does a double bond effect melting point?
Decreases MP
Lipids are soluble in polar or non-polar solutions
Non-Polar
How are Terpenes Constructed
Constructed fro 5-Carbon Isoprene units, with atleast 1 double bond
(divisible by 5)
Terpenes are what marcomolecule
Lipids
Kinetic CTRL favours what 3 things?
- Low Temp.
- Short Rxn Time
- Less Stable Product
Thermodynamic Ctrl favours what 3 things?
- High Temp.
- Long Rxn Time
- More Stable Product
The double bonds on a kinetic enolate will be where?
One Ends (primary)
Shorter Rxn Time: Means the Ha is easily accesible
Less Sub. Double Bonds = Less Stable
The double bonds on a thermodynamic enolate will be where
In middle/btwn (secondary
More Sub. Double Bonds = More Stable
Longer Reaction Time cuz HB is sterically indered
How to ensure Kinetic Enolate is formed
1)Use Large Powerful Base (LDA)
2)Low Temp.
-Trap and irreversibly form Kinetic Enolate
How to ensure Thermodynamic Enolate is formed?
1)USe Small and Weak Nase (OEt)
2)High Temp
Establishes a equilibrium between all 3 structures favours the more stable thermo enolate
Compare the energy diagrams for kinetic and theromdynamic enolate
Kinetic:
-Lower Ea (Lower hump)
-Higher energy product (more reactive, less stable)
Thermo:
-Higher Ea (Higher Hump)
-Lower energy product (less reactive, more stable)
What is a solution?
homogenous mixture of two or more solvents, composed of solutes(s) dissolved in a solvent
How do like (polar and polar/ non-polar and non-polar) dissolve/interat with eachother
Breaking solvent-solvent intermolecular bonds to form solute-solvent intermolecular bonds
What is solvation/hydration
When an ionic compound is dissolved in a solvent it dissociates into ions that are surrounded by the polar solvent
When a compound is hydrated what phase does it exist in?
Aq
Electrolyte
any ion that can by hydrated
What is Molar Solubility?
Moles per litre that can dissolve based on the concentration of product ions
Normality
Gram equivalent weight of solute per meter but take stoich ratios into account
Molarity of compound x stoich ratio
What is vapour pressure?
The pressure exerted by a gas in equilibrium with its condensed phase (liquid phase)
-The amount of evaporation
When has dynamic equilibrium been established in terms of vapour pressure?
When evaporation = condensation
(when molecules in gas phase equal the molecules in liquid phase
The vapour pressure of a liquid depends on what?
Temperature
Increasing temperature has what effect on vapour pressure
Increased temp. = increased vaour pressure
Positive correlated
When does the boiling pt occur in terms of vapour pressure
Vapour Pressure = external pressure acting on the surface of a liquid
If a molecule has a high vapour pressure compared to another that same temperature it means it evaporates more or less easily?
Easily Evaporates
A molecule with more intermolecular forces will have a lower or higher vapour pressure at a certain temperatuer
lower vapour peressure
Intermolecular forces require high temp to dissosciated (require higher KE)
Increased amount of intermolecular forces effect vapour pressure how?
Decreased
What is the normal BP?
For any liquid: the temperature at which its vapour pressure is equal to ATM pressure (1 atm)
Bond breaking is endothermic or exothermic
Endothermic
Bond formation is endothermic or exothermic
Exothermic
If the overall enthalpy change in a solution is negative what does it mean about the strength/stability of the new solution compared to the old solution
More stable/strong intermolecular bonds between solute-solvent than the orginal
Energy is lost from the system
What is a non-volatile solute
No Vapour Pressure
NaCl
Glucose
Urea
What is the effect of a non-volatile solute on solvent-solvent interactions?
Disrupt the solvent-solvent interaction by forming stronger solute-solvent interactions
DECREASING EVAPORATION
What is the effect of a non-volatile solute on vapour pressure of the liquid at all temperature?
decreases vapour pressure
Higher Boiling Point
What occurs to a vapour pressure curve in response to an addition to a non-volatile solution
Downards and To Right
DEcreased pressure and increased boiing point
What are the 2 major effects of a non-volatile solute on a solution of all temperature?
Increased Boiling Point
Decreased Vapour Pressure
What is Raoults Law
Change in vapour pressure of an ideal liquid upon addition of a non-volatile solute
AMMONIUM
NH4+
H3O+
HYDRONIUM
OH-
HYDROXIDE
CN-
CYANIDE
CO3(2-)
CARBONATE
HCO3(2-)
BICARBONATE
CH3CO2-
ACETATE
C2O4(2-)
OXALATE
NO2-
NITRATE
SO4(2-)
SULFATE
PO4(3-)
PHOSPHATE
Solubility of GASES increases or decreases with increasing temperature
decreases
Solubility of salt in liquid increases or decreases with increasing temperature
increases
When calculating oxidation numbers what to do with double bonds?
They count as there own
3 Rules for assigning oxidation numbers?
1)Oxidation number of any molecule/ion/atom adds to its charge
2)Consider the charge that the elements want
3)Consider EN/#E
-More EN will take the negative charge
-It can only go with the amount of electrons possible
How to solve redox reactions
1)Separate the reaction into ions (half reactions)
2)Balance the half reactions
-Add H2O or H or OH
3)Balance the charges for the half reaction by adding electrons
4)Balance the entire reaction charge (multiply each half reaction by the entire thing)
5)Add the half reactions together (Electrons should cancel)
True or False there should be electrons in a balance redox reaction
False, NO ELECTRONS
REDOX rxn how to balance oxygen and hydrogen atoms of half reaction in acidic solution?
H2O to balance any Oxygen
H+ to balance any H Atoms
REDOX rxn how to balance oxygen and hydrogen atoms of half reaction in basic solution?
OH- to balance oxygen
H+ to balance any H atoms
What is a reaction potential
How much the rxn wants to go
Standard potential is often given as reduction or oxidation potential
Reduction
(flip sign to make it oxidation)
The standard redox is equal to the
cell voltage
The anode in a electrochemical cell is where oxidation or reduction occurs
Oxidation (loos e)
-contains reducing agent
The cathode in a electrochemical cell is where oxidation or reduction occurs
reduction (gain e)
-contains oxidation agent
Galvanic/Voltage Cells are spont. or non-spont
Spontaneous
Electrolytic cells are spont. or non. spont
Non-Spontaneous
(have to push electrons towards negative side, then released to positive side)
Galvanic/Voltalic Cells produce or require energy
Produce energy and electric current
Electrolytic cells produce or require energy
Require energy/ need energy to be supplied to drive the reaction
Galvanic cells the anion is ____ and the cathode is _____
Anion is negative
Cathode is positive
Electrolytic cells the anion is ______ and the cathode is _______
Anion in positive
Cathode is negative
Electrons go in the wrong direction
Electrons always travel which way n a electrolytic cell
Anode to Cathode
Good guess for electrochemical cells when running out of time of the side of anode and cathode
Anode is L
Cathode is R
Current in a electrolytic cell moves in what direction
Opposite to electron flow
cathode to anode
What does a salt bridge do?
Disipates the resulting charge in the anode and cathode by release either a positive or negative charge (opposite to what the side is releasing) making it neutral
ex.
Zn releases Zn2+ therefore SO42- in salt bridges neutralizes the 2+ charge with a 2- charge
What are the 2 faradays laws of electrolysis?
1)Mass of material at an electrode from electrolysis is directly propotional to the amount of electricity being transferred
2)Equivalant amounts of electricity will produce different amounts of material proportional to the materials weight
What is voltaic cell
A electrochemical cell that uses the same reactants and products at the anode and cathode, but DIFFERENT CONCENTRATIONS to allow a potential to be generated
In a voltaic cell the reactants will have a higher or lower concentration
HIGHER concentration
Decreased KSP means more or less is dissolved
LESS
Increased binding is associated with a high or low K value
high K Value
Explain how a galvanic voltanic cell works
1) Anode is oxidized (electrons are released)
2)Electrons travel towards cathode
3)Current moves in direction towards opposite electrons (towards anode)
4)Electrons reduce the cathode
5) Salt bridge dissipate charges gradient
In the cathode what reaction occurs
Reduction
The aquous soution gains electron and forms a solid
Cu2+ + 2e- = Cu(s)
Partcipate formed
In the anode what reaction occurs
Oxidation
The solid looses electrons into its aq solution
Zn(s) –> Zn2+ + 2e-
