Chem and Orgo Flashcards
Why are cycloalkanes unlikely to have derivatives?
For a molecule to have derivatives, it must be able to react in a way to create the derivatives— can’t be non-reactive
True or false: organic solvents are ideal for hydrogen bonding
FALSE: can’t H bond with organic solvents— think of all the CH bonds!
Which is the proper pairing of amino acid configurations?
- S/R and D/L
- S/D and L/R
- S/L and D/R
S/L and D/R
S enantiomer goes with L rotation
R enantiomer goes with D rotation
If a molecule has 3 chiral centers, how many stereoisomers does it have?
2 stereoisomers for each chiral center
So 3 chiral centers = 2^3 stereoisomers
What are the necessary characteristics of stereoisomers?
Stereoisomers must have 4 different substituents, no double bonds
What is the difference between nucleophiles and electrophiles?
Nucleophiles have a charge or a lone pair, they donate electrons to electrophiles, which are electron deficient
What is the name of a hemiacetal ring that has its aldehyde oxidized to carboxylic acid during the time it is in its open-chain conformation?
Aldonic acids
Oxidized aloses
Why are monosaccarides with a hemiacetal ring considered reducing sugars?
When the hemiacetal ring is in its open chain form as it switches between alpha/beta configurations, the aldehyde can be oxidized to carboxylic acid (oxidized aldose)
Aldoses can be oxidized, so they are considered reducing agents
So any monosaccharide with a hemiacetal ring is a reducing sugar
What is tautomerization?
Rearrangement of binds in a compound
Usually by moving a hydrogen and forming a double bond
What is the difference in deoxyribonucleic acid and ribonucleic acid and how can you tell the difference from their names alone?
Deoxyribonucleic acid has a hydrogen instead of a hydroxide
(Ribonucelic acid has a hydroxyl in this position)
Deoxy sugars contain a hydrogen that replaces a hydroxyl group
What reaction do hexokinase and glucokinase (the analogous enzyme in the liver and pancreatic beta cells) catalyze?
Phosphorylation of glucose in glycolysis
Hemiacetals/hemiketals react with alcohols to form acetals/ketals under what condition?
Under acidic conditions, hemiacetals/hemiketals react with alcohols to form acetals/ketals
True or false: anomeric carbons of cyclic sugars can react with any hydroxyl group of any other sugar molecule, regardless of alpha or beta configuration
TRUE: formation of an alpha or beta glycosidic linkage is nonspecific
What is the technical name for sucrose?
Glucose-alpha-1,2-fructose
What is maltose a disaccharide of?
2 glucose molecules
Glucose-alpha-1,4-glucose
What is the difference between estérification and glycoside formation?
Estérification: hydroxyl group + carboxylic acid or derivative
glycoside formation: alcohol group + hemiacetal/ketal on sugar to form alkoxy group
What is the metabolic value in carbohydrates being oxidized?
Carbohydrates reduce other molecules
Aerobic metabolism requires reduced electron carriers
What is the effect of lowering the temperature in gas chromatography?
GC is for 2 liquids with significant changes in BP
lower temperature = longer retention time = more resolution between peaks
How does polarity affect boiling point?
More polar = higher BP
What does mass spectrometry measure?
Mass to charge ratio
What happens when an electron absorbs energy?
Electron absorbs energy, becomes excited, releases light and relaxes to ground state
The Henderson-Hasselbalch equation states that for every 1 unit difference between pKa and pH…
For every 1 unit change between pKa and pH, ratio of acid/base or base/acid changes by a factor of 10 (for every 2 units, factor of 100, and so on)
When the pH > pKa …
More base than acid
Why does CO2 buildup in the blood cause acidosis?
CO2 buildup —> right shift of equilibrium, favoring products —> acidosis
How does decreasing salt concentration affect hydrophobic chromatography?
Hydrophobic chromatography relies on high salt concentrations to strengthen hydrophobic interactions
Decrease causes protein to dissociate from column
What is the range of visible spectrum wavelength?
390-700nm
Violet- 390nm
Red- 700nm
Which has higher boiling points, trans or cis stereoisomers?
Trans has higher BP
cis generally more compact, trans generally linear—> pack tighter
What is sucrose made of?
Glucose (6 membered) + fructose (5 membered)
Mannose And glucose are…
Epimers
What are different about dideoxyriboses ?
Deoxyribose = no 3’ hydroxyl
So
Dideoxyribose = no 2’ or 3’ hydroxyl
What is the equation for work function? Which electrons does it refer too?
E = hf0 where E is the work function, h is Planck’s constant, f0 is threshold frequency
Minimum energy needed to remove valence electrons
What happens to the excess energy when the energy added is greater than the work function?
Excess energy is transferred to kinetic energy of ejected electron
A metal with a work function of 500J is struck by a photon of 500J. The electron will:
The work function = the energy
So the electron will be free from its attraction to the nucleus
But it will not move because it lacks excess energy to be converted to KE
An atom undergoes radioactive decay, resulting in the atomic mass number being reduced by 4 and the atomic number being reduced by 2. What kind of decay is this?
Alpha decay- loss of one He nucleus, which has mass number of 4 and atomic number of 2
An atom undergoes radioactive decay which changes a neutron into a proton with ejection of an electron. What type of decay is this?
Beta decay- neutron chantes to proton, electron ejected
Which type of decay does not change the number of nucleons?
Gamma emission- byproduct of other types of decay. No change in number of nucleons
True or false: binding orbitals are higher in energy than antibonding orbitals
FALSE: antibonding orbitals are higher in energy than bonding orbitals
“Out of phase” electrons that are “repulsive”
Is energy released or required to form a bond?
Energy is always released when a bond is formed
ATP->ADP releases energy because the bonds formed in making ADP releases more energy than what is required to break ATP bonds
When nitrate loses an oxygen it becomes what?
Nitrate: NO3-
Nitrite: NO2-
Name the following:
- ClO3-
- ClO4-
- ClO2-
- ClO-
Hypochlorite: ClO-
Chlorite: ClO2-
Chlorate: ClO3-
Perchlorate: ClO4-
When balancing a chemical reaction, which atoms should you balance first?
Balancing reaction:
- Balance carbons
- Balance hydrogens
- Balance oxygens
Then do the other atoms
Which requires more oxygen to combust, propane (C3H8) or propanol (C3H8O)?
Quick trip for finding high species requires most oxygen to combust:
Add 1 for each C, subtract 0.5 for each O
Propane: (3x1) - (0x0.5) = 3
Propanol: (3x1) - (1x0.5) = 2.5
Propane requires more energy to combust
How does increasing pressure affect a reaction at equilibrium?
Increasing pressure causes shift in reaction towards side with fewer moles of gas
What are the axis of a first order reaction graph?
ln[A] vs time
Linear with a slope of -k
A rate order graph shows 1/[A] vs time that is linear with a slope of k. What order reaction is this?
Second order reaction
What is the structure of acetone?
CH3(C=O)CH3
Has ketone group
What does combustion produce?
Combustion —> CO2 + H2O
What is the best way to tell if molecules exhibit similar properties?
Do they contain atoms from the same periodic groups?
Which groups on the periodic table easily replace Hydrogen in a single replacement reaction?
Groups 1&2 easily replace hydrogen in single replacement
Hydrogen gas always produced
According to the activity series, can fluoride replace bromine in a single replacement?
Yes: for halide to replace another halide, it must be above it on periodic table (more electronegative)
What does HCO3 dissociate into?
HCO3 -> CO2 + H2O
What gas does the reaction between CaBr2 and F2 produce?
CaBr2 + F2 -> CaF2 + Br(g)
Fluorine is more electronegative than Bromine so it can replace it
What gas will the reaction between CaSO3 and HCl produce?
CaSO3 + HCl -> H2SO3 + CaCl
H2SO3 dissociates into SO2(g) and H+
What gas will H2CO3 produce?
H2CO3 -> CO2(g) + H2O
What gas will H2SO2 produce?
H2SO2 -> SO2(g) + H2O
What gas will NH4OH produce?
NH4OH -> NH3(g) + H2O
What gas is produced in a reaction with sulfide?
Sulfide produces H2S(g) in reaction
Which of the following is a stronger nucleophile?
OH- or H2O
OH- is a stronger nucleophile than H2O —> negatively charged nucleophile is always stronger than its neutral component
Which is the stronger nucleophile?
NH3 or H2O
NH3 is a stronger nucleophile than H2O —> N vs O, nucleophilicity decreases L->R on periodic table
As size and polarizability increase down the periodic table, nucleophilicity…
Nucleophilicity increases down the periodic table as size and polarizability increase
Will bronsted lowry or Lewis acid-base reaction occur faster?
Bronsted Lowry occurs faster than Lewis
Bronsted Lowry: acid is H+ donor
Lewis: acid accepts e- pair
Which is likely to form coordinate covalent bond with nickel?
BF3
PH3
NH4+
PH3
Coordination covalent bond between transition metal with positive oxidation state and atom with lone pair
How do radius and ionization energy predict electronegativity?
Small radius and large ionization energy —> high electronegativity
True or false: covalent bonds can conduct electricity in solution
TRUE: some covalent bonds can conduct electricity in solution (HCl)
What is the only thing that changes the value of Keq?
TEMPERATURE
What is likely to cause each of the following:
Changing colors in a flame test
Changing colors in solution chemistry
Flame test = photon emission
Solution chemistry = partially filled d orbitals of transition metals
You make a solution by adding 200mL of 0.8M Fe2(SO4)3 to 2L water. How many moles of sulfate ions are present?
M = mol/L (0.8)(0.2L) = 0.16mol of Fe2(SO4)3
There are 3 moles of SO4 in this compound, so 0.16 x 3 = 4.8x10^-1
How many more neutrons are there than electrons in 54Fe+? (Fe atomic number is 26)
54-26= 28 neutrons
Fe+ also has a 1+ charge
So 3 more neutrons than electrons
How does lowering the temperature affect gas chromatography?
GC- for 2 liquids with big differences in BP
Lower temp = longer retention time = more resolution between peaks
How does polarity affect boiling point?
More polar = higher BP
What does mass spectrometry measure?
Charge-to-mass ratios
What happens when an electron is excited by absorption of energy?
Electron releases photon (light), relaxes to original energy state
If the pH > pKa what is the ratio of acid to base
pH > pKa = more base than acid
Complete this sentence:
According to Henderson-Hasselbalch, for every 1 unit difference between pKa and pH….
For every 1 unit difference between pKa and pH, ratio of acid/base changes by a factor of 10
For every 2 units, factor of 100… so on…
What effect does buildup of CO2 in the blood have?
CO2 buildup in blood causes acidosis
Shifts bicarbonate buffer equation right (CO2 is a reactant)
CO2 + H2O -> H2CO3 -> H + HCO3
How will decreasing the salt concentration of the eluent affect hydrophobic chromatography?
Hydrophobic chromatography- relies on high [salt] to strengthen hydrophobic interactions
Decreased [salt] causes proteins to dissociate (weaker interactions)
What is the range of visible spectrum?
390-700nm
Violet is lowest, red is highest
Do cis or trans isomers have higher BP?
Trans isomers have higher BP
trans are generally more linear, cis do not pack as tightly
What is sucrose made of And what numbered rings are these?
Sucrose = glucose (6 membered) + fructose (5 membered)
In size exclusion chromatography, which molecules elute first?
Large molecules elute first in size exclusion chromatography
As arteries narrow, how is velocity of blood flow affected?
Q=AV
narrower artery (smaller area due to smaller radius) increases velocity
Given that deoxyribose has no 3’ hydroxyl, what can you infer about dideoxyribose?
Dideoxyribose - no 2’ or 3’ hydroxyl
What Is a black body radiator?
Black body radiators absorb all energy and emit 100% of energy as electromagnetic radiation
Which type of calorimeter provides content pressure and which type provides constant volume?
Coffee cup- open to atmosphere, so constant pressure. Allows for PV work
Bomb calorimeter- sealed, so constant volume. Does not give enthalpy but measures change in interval energy
What is the difference between an isolated and closed system?
Isolated system- no exchange with environment
Closed system- only energy exchange with environment (deltaE = q + w)
A high heat of combustion is associated with stable or unstable molecules?
Unstable molecule = high heat of combustion (going from unstable to stable molecule, heat released)
What is the fundamental thermodynamic equation?
deltaG = deltaH - TdeltaS
What are Arrhenius acids and bases?
acid- produces H+
Base- produces OH-
How is a bronsted Lowry acid different than a Lewis acid?
Bronsted Lowry- acids donate protons (H+), bases accept protons
Lewis- acids accept electrons, bases donate electrons
In the ionization of water, how does adding a base affect the equilibrium of the ionization of water?
Adding either an acid or base shifts the equilibrium for ionization of water to the left
H2O + H2O <> H3O+ + OH-
What are the strong acids?
HI, HBr, HCl, HNO3, HClO4, HClO3, H2SO4, H3O+
Why is HF not a good acid?
F is too small- cannot spread charge, conjugate base would be unstable
Where is the half equivalent point in a titration curve?
Half equivalence point- middle of nearly horizontal section
[HA] = [A-]
After Crossfit, your body maintains homeostasis by which of these?
Conduction
Convention
Radiation
Conduction- direct contact
Radiation- heat release
Not convection (heat rises)
Which of these has the larger negative heat of combustion?
HF (bond energy= 600kJ/mol)
F2 (bond energy= 150kJ/mol)
Unstable species = larger negative heat of combustion (going from unstable to stable molecule)
F2 (small bond energy) has larger negative heat of combustion
Which of these must increase entropy of a system?
Pressure or volume
Volume
Pressure does not increase entropy (disorder). Think about how increasing pressure of gas creates solid (less disorder)
0.001kg mass increases temp from 250K to 275K when 1000J is applied. What is specific heat capacity?
Q = mc(delta)T
1000J = (0.001kg)c(275-250K)
c = 4x10^4 J/kg•K
Heat source of 50Watts of power submerged in bucket of 1kg water. How long will it take to raise temp of water by 5 C? (Water specific heat = 4.18 kJ/kg•C)
50 watts = 50 J/s
Q = mc(delta)T
Q = (1)(4.18)(5) ~ 20 kJ
20kJ = 20,000J x (1 s/ 50J) x (1min/60s)
~7 minutes
A rxn known to have very high activation energy can also have which of the following:
Fast reaction rate
deltaG < 0
very large Keq
Can have all of these
High temp can induce fast reaction rate
deltaG can be < 0 if temp and entropy increase is high enough
Keq can be large- can produce a lot of products at equilibrium, just takes more energy to get there
Which of these has the lowest Ka? HClO4 HClO3 HClO2 HClO
Low Ka = least acidic
HClO is least acidic- conjugate base not as stable (less resonance because less oxygen atoms)
What are the strong bases?
Group IA hydroxides (NaOH, KOH, etc) NH2- H- Ca(OH)2 Sr(OH)2 Ba(OH)2 Na2O CaO
Which 2 atoms in the first 3 rows of the periodic table are stable with 6 valence e (but can have up to 8)?
Boron (B) and beryllium (Be)
How many oxygens go with each of these naming conventions? “Per- -ate” “-ate” “-ite” “Hypo- -ite”
“Per- -ate” —> 4 O
“-ate” —> 3 O
“-ite” —> 2 O
“Hypo- -ite” —> 1 O
Also: “ate” = “-ic acid”
“ite” = “-ous acid”
(There are some exceptions)
How do you know something is a nucleophile?
Lone pair, negative charge, double or triple bond
How do you know something is an electrophile?
Atom attached to strong electron withdrawing group, positive charge, carbocation
What’s a carbonyl group, how does it effect reactivity of nearby groups?
Carbonyl: C=O
Strong electron withdrawing group because O is very electronegative, so C has a partial positive charge
Could reduce the nucelophilicity of nearby group
Is oxygen electron donating or withdrawing?
O IS ELECTRON WITHDRAWING
If something is a good leaving group, is it a good nucleophile?
NO. too stable on its own
In general you can think of nucleophiles as bases, except in this situation:
If it’s really bulky, it can be a base but not a nucleophile
Match:
Carbocation/ carbanion
Electrophile/ nucleophile
Carbocation = electrophile Carbanion = nucleophile
So alkyl groups donate or withdraw electrons?
Alkyl groups are electron donating, due to dipole moments!
Decarboxylation always forms what as a leaving group?
CO2 is always leaving group of decarboxylation. What’s left behind always has a negative charge on the C (nucleophile), can be reacted with further
When giving priority in R/S convention, what should you do when the bonded atom has a double bond after it (if comparing it in a tie)?
Count the atom bonded via double bond twice (C=O is like 2 O’s, C=C is like 2 C’s, so C=O would be higher priority)
A leaving groups leaves what behind? deprotonation leaves what behind?
Leaving group —> carbocation
Deprotonation (H) —> carbanion
Describe the general structure of an amine
Lone pairs on top of N, bonded to something below
What’s the formula for glucose?
C6H12O6
What’s the charge of sulfate ion?
-2
Which of these is not a coordinate covalent bond?
Cu(NH3)4^2+
Co(CH4)4^2+
Ni(PBr3)4^2+
Co(CH4)4^2+ is NOT a coordinate covalent bond because CH4 doesn’t have a lone pair
What explains the reactivity of metals in water going down a period?
Decreasing ionization energy (easier to be IONIZED)
If a question says calcium reacts with water, is it solid or aqueous?
SOLID. Otherwise it would say aqueous calcium
What’s the structure of acetone?
CH3-C=O-CH3
What should you do when asked what species requires the most oxygen to combust?
+1 for each C, -0.5 for each O
The largest number will require the most O2 to combust
What is Avogadro’s number?
6x10^23
Which increases yield:
Increasing temperature
Removing product
REMOVING PRODUCT
temperature affects rate, not yield
What’s the energy of a photon?
E = hf
What happens in beta decay?
Neutron is changed into a proton, an electron is lost
How many lone pairs does chlorate have?
ClO3-
One lone pair
What is the VESPR geometry of SF4?
4 substituents, 1 lone pair
See-saw
What is the VESPR geometry of BeF3?
3 substituents, 2 lone pairs
T shaped
If Br and Cl are cis and adjacent on a cyclohexane, what will the cyclohexane lowest energy conformation be?
Br is larger so it will be equatorial, Cl will be axial (they can’t both be equatorial when they are cis and adjacent)
What is the formula of nitrate?
NO3-
No lone pairs on nitrogen
When you abstract a proton from a hydrocarbon, what is left behind?
Carbanion
What is the formula and structure of nitrite?
NO2-
One O is double bonded, the other is single bonded and has negative charge
N has no formal charge, 1 lone pair
How many lone pairs are on chlorite?
ClO2-
One O is double bonded the other carries a negative charge
Cl has 2 lone pairs
Carboxyl group is removed from carbon chain and CO2 is produced. What is this process and what type of intermediate is formed?
Decarboxylation (-COOH is removed)
Carbanion (negative charge)
For a greater overlap of p orbitals in a double bond, the atoms should be:
Smaller
Larger
Smaller- able to get closer to each other
What is the s character of sp, sp2, and sp3 hybridizations?
Sp- 50% s character
Sp2- 33% s character
Sp3- 25% s character
When enantiomers react with a chiral molecule, how many products are produced?
2 different substances are produced, 1 for each enantiomer
NaBH4 will reduce aldehydes to what kind of alcohol
Primary
NaBH4 will reduce ketones to what kind of alcohol
Secondary
Creates chiral carbon- 1 H, 1 OH, 1 methyl, 1 R group
Which has a lone pair, ammonium or ammonia?
Ammonia has lone pair (NH3)
How does separation of charge factor into resonance contribution?
Least separation of charge = major contributor of resonance
Are alkenes nucleophilic or electrophile?
Alkenes are electron dense, and so nucleophilic
Are electrophile electron withdrawing or donating, and what charge will they have?
Positive charge = electron withdrawing
When distinguishing between a nucleophile and a base, what should you consider?
Size- bulky molecule will act as a base
what do Grignard reactants do?
Reduce carbonyl to alcohol while adding R group- lengthen C chain
Reduction of carbonyl via LiAlH4 would add which to carbonyl carbon?
Methyl group
Hydrogen
Hydrogen
What does the Witting reaction do?
Carbonyl is replaced with alkene
Jones reagents are good for what?
Strong oxidizing agents
What is more basic OR- or OH-?
OR- is more basic because carbon chain (R) is weakly electron donating (to O, giving partial negative) while H is neutral
What mass of cyanide in the bloodstream corresponds to a lethal blood cyanide level for a person whose total blood volume is 4.8L, if 115uM is lethal? (Molar mass of cyanide is 26g/mol)
(115x10^-6mol/L)(4.8L)(26g/mol)
= 0.014g or 14mg
You’re halfway submerged under water (you’re 80kg and weigh 784N). If your density is the same as water, what’s your apparent weight?
You’re the same density as water, so just divide your weight in half for half submerged —> 392N
What’s the empirical formula of the conjugate acid of the anion in strontium acetate, Sr(CH3COO)2?
The anion is acetate, the conjugate acid of acetate is acetic acid —> C2H4O2 (extra H)
Reduce this to find empirical formula- CH2O
How does length of an extended conjugated double bond system affect its light absorption?
Longer conjugated double bond system, longer the wavelength of visible light that will be absorbed (so lower frequency light)
An inhibitor is found to bind enzyme only after substrate is bound. What kind is it?
Uncompetitive inhibitor
An inhibitor is found to bind either bound or unbound enzyme equally. What kind is it?
Non competitive inhibitor
What does Km represent?
Affinity of enzyme for its substrate
Substrate concentration that will produce initial velocity 1/2 Vmax
What kind of inhibitor is best for continuous inhibition?
Noncompetitive- inhibitor will reduce reaction velocity at any substrate concentration (binds allosteric site)
(Competitive inhibitors can be overcome at high substrate concentration)
What is the oxidation state of manganese in MnO2?
Oxygen has -2 oxidation state, so to balance out both oxygens, Mn must have oxidation state +4
(Manganese (IV) oxide)
Acetoacetic acid can be used as fuel in starvation except in: Heart Liver Brain Muscles
Liver
Acetoacetic acid is ketone body, and liver lacks enzyme to convert ketone bodies to ATP (because liver produces ketone bodies when blood glucose is low)
Rate of substrate turnover was measured for an enzyme with Vmax of 2uMs^-1 and Km of 15uM. What is the initial velocity when substrate concentration is 5uM?
Need MM equation:
V0 = (Vmax*[S]) / (Km + [S])
V0 = (2*5)/(15+5) = 0.5uM^-1
True or false: antibonding orbitals are lowest in energy
FALSE: antibonding orbitals are highest in energy and decrease molecular stability (whether partially or completely filled)
To be aromatic, molecule must adhere to 2 things:
Must be planar, and follow 4n+2 rule
(Cis or trans orientation of bonds is irrelevant)
4n+2 rule: count number of pi electrons. 4n+2 will equal number of pi electrons. If you solve for n, it must be a whole number (then it is aromatic)
How does 4n+2 rule work?
Count number of pi electrons
4n+2 = number of pi electrons
Solve for n, it must be a whole number
(Pi electrons: electrons with pi bonds, or lone pairs within p orbitals)
How do you calculate power in constant velocity situations?
P = force x velocity
How do Archimedes principle and Bernoulli effect differ in their relation to fluids?
Archimedes principle relates to static fluids
Bernoulli effect relates to dynamic fluids (like effect of fluid speed on pressure)
What is the energy of photons at wavelength 584nm?
E = hc/I
E = (6.6x10^-34 x 3x10^8) / (584x10^-9) = 3.4x10^-19J
What charge will the intermediates of aldol addition and condensation reactions have?
Aldol addition and condensation reactions proceed under basic conditions by abstraction of the acidic alpha carbon hydrogen
Intermediates will have negative charges (so you will NOT have a carbocation)
Aldol addition: ketone enolate (nucleophile) and aldehyde (electrophile) produce aldol (C-C bond formed)
(Enolate: organic anions from deprotonation of carbonyl compounds)
Which will have greater p orbital overlap:
C=O
N=O
N=O
Smaller atom will be able to get closer
Atom size decreases left to right because of electronegativity
What’s the structure and VESPR geometry of sulfur dioxide?
SO2 has S double bonded to both O, and a lone pair (doesn’t follow octet)
Bent shape
True or false: tetra-substituted alkenes are the least stable and therefore most reactive
FALSE: tetra substituted alkenes are the MOST stable (low heat of combustion), but ARE more reactive as nucleophiles
Which is an electrophile:
CH2CH2
HCl
Alkenes are NOT electrophiles but HCl is a GREAT electrophile
Which is the most basic substituent:
Cl
OH
OR
OR- carbon is more electron donating than hydrogen
Cl is a weak base because it is the conjugate base of a strong acid (so it’s stable)
Which is stronger- sigma bond or pi bond?
Sigma bond
Higher electron density (head-to-head overlap is closer together)
HOWEVER a double bond (a pi bond plus a sigma bond) is stronger together than a single bond
What type of bond is most reactive?
Triple bonds (because pi bond is more reactive than sigma bond)
Reactivity has to do with tendency of third bond (a pi bond) to react
What are the possible VESPR shapes of sp2 hybridization?
Trigonal planar or or bent (1 lone pair)
What are the possible VESPR shapes of sp3 hybridization?
Tetrahedral
Trigonal pyramidal (1 lone pair)
Bent (2 lone pairs)
How is iron bonded in the heme unit of hemoglobin?
Coordinate covalent bond
Which atoms are stable with 6 valence e?
Boron and beryllium
Which atoms on the periodic table can accept more than 8 electrons?
Third period or higher
PCl5, SF6, (PO4)3-, (SO4)2-
What is an aryl functional group?
Benzene ring as functional group
What is a hydrazine functional group?
NH2-NH2
What is a vinyl functional group?
-CH=CH2
What is an imine functional group?
R1R2-C=N-R3
N has a lone pair
What is an acyl functional group?
R(C=O)-
What is a sulphone functional group?
S double bonded to 2 O’s, and single bonded to 2 R groups
What is a hemiacetal?
What is an acetal?
Hemiacetal: Alcohol and ether attached to the same carbon
Acetal: 2 ethers attached to same carbon
What is a hemiketal?
What is a ketal?
Hemiketal: An alcohol and an ether attached the same carbon, along with 2 other carbons
Ketal: 2 ethers attached to same carbon, along with 2 other carbons
Dextrorotary rotates light in which direction?
Clockwise, +
Levorotary rotates light in which direction?
CCW, (-)
In E/Z convention, which is same side and which is opposite side to have higher priority substituents?
Z = same side (cis)
E = opposite side (trans)
In anomers, if the anomeric OH/OR group and the CH2OH group are on the same side, it is…
Beta
n anomers, if the anomeric OH/OR group and the CH2OH group are on different side, it is…
Alpha
Bases abstract (fill in the blank)
Nucleophiles attack (fill in the blank)
Bases abstract protons (hydrogens)
Nucleophiles attack carbons (or other central atoms)
Basicity is a function of ___
Nucelophilicity is a function of ___
Basicity —> thermodynamics (compares stability of reacted and unreacted base)
Nucelophilicity —> kinetics (rate at which it reacts with electrophile)
Which substitution reaction will create racemic mixture?
SN1
Which reactions prefer polar protic solvents?
E1, SN1
True or false: combustion of an alkane is radical and exothermic
TRUE. Has high energy of activation
Alkane reacted with H2 in presence of metal catalyst gives what?
Syn addition (H bonds added on same side)
Are alkenes nucleophiles?
Yes. Pi electrons in double bond will attack electrophiles (leave behind carbocation)
What is the formula of benzene?
C6H5
How can alcohols act as both nucleophiles and Lewis acid?
Nucleophile- lone pair acts as Lewis base
Lewis acid- when oxidized to carbonyl group, oxygen accepts pairs of electrons from the OH bond as proton is abstracted
How does substitution affect alcohol acidity?
Less substituted alcohols are more acidic
Tertiary alcohols are destabilized by induction
Oxidation of secondary alcohols form:
Ketones
Can tertiary alcohols be oxidized?
No
Primary alcohols can be oxidized to ___ which is further easily oxidized to ___
Primary alcohol -> aldehyde -> carboxylic acid
What are the Jones, Collins, PCC, PDC, O3, CrO4, and KMnO4 reagents used for?
Oxidation
What can NaBH4 reduce?
What can LiAlH4 or H2/pressure reduce?
NaBH4- aldehydes and ketones
LiAlH4 or H2/pressure- aldehydes, ketones, carboxylic acids, esters (stronger reagent)
LiAlH4 produces 2 equivalent of H-, NaBH4 only produces 1
When Vic-diol is combined with hot acid (Pinacol Rearrangement), what do you get?
Ketone or aldehyde
“Vic”= adjacent (2 adjacent hydroxyl groups)
Carbons with functional groups must be tri- or tetra- substituted
—> tri = aldehyde
—> tetra = ketone
What is forming tosylates and mesylates good for?
They make great leaving groups
Formation of a tosylate/mesylate is what kind of reaction?
SN2
Alcohol attacks tosyl/mesyl halide (kicks off halide)
Is dehydration of an alcohol an equilibrium reaction?
Yes
In dehydration of an alcohol (equilibrium reaction), what conditions favor alkene and what conditions factor alcohol?
Alkene- hot, concentrated acid
Alcohol- cold, dilute acid
Protonation of alcohol with extension or carbon chain is what kind of reaction?
What reagent does it use?
Grignard synthesis
RMgX (usually RMgBr)
What are ethers and how reactive are they?
R-O-R
NOT reactive
EXCELLENT solvent
Do alkenes donate or withdraw electrons?
Alkenes are weakly electron withdrawing
Electron donating groups increase or decrease basicity?
Increase
Carbocations are always formed on most stable carbocation except when? (Tertiary > secondary > primary)
When peroxides are present
Which will give the greatest heat of combustion?
- molecule with least negative heat of combustion
- highest bond energy
molecule with least negative heat of combustion or smallest bond energy = least stable = highest heat of combustion
Compare the difference in acid/base strength when making a buffer and when titrating
Buffer- weak acid/weak base or strong acid/ strong base
Titration- weak acid/strong base or weak base/strong acid
What does Ksp describe?
Equilibrium constant specific for solubility
What type of molecule is palmitoleic acid?
Fatty acid. Hydrophobic carbon chain and acidic group
What does an IR peak at 3200-3500 represent?
Carboxylic acid OH
What does an IR peak at 1700-1750 represent?
Carbonyl (C=O)
What does an IR peak at 1580-1610 represent?
Conjugated C=C (like in benzene)
In the context of binding affinities, what does a high Ka represent?
High affinity binding (Ka > 1)
What is e- configuration of Zn2+ (atomic # is 30)?
1s2 2s2 2p6 3s2 3p6 4s2 3d10
Or
1s2 2s2 2p6 3s2 3p6 4s0 3d10
1s2 2s2 2p6 3s2 3p6 4s0 3d10
4s subshell has highest principle quantum number so it empties first
How many electrons can be held in the 3rd shell of an atom?
Max number of electrons allowed in a shell = 2n^2
So if n=3 …. 18 electrons
In the 4th subshell of an atom, how many electrons can there be?
Max number of electrons in a subshell = 4l+2
So in 4th subshell, l=4
So… 18 electrons
Which elements in the periodic table can only have paired electrons in their ground state?
Elements on the end of a block (s, p, d, f block)
What is the equation for angular momentum?
L = mvr
What two equations combine to give that for the energy of a photon?
E = hf
c = f x wavelength
…
E = hc/wavelength
Is the energy difference greater between the 3 and 4th shells or the 1 and 2nd shells?
Difference in energy is function of:
[1/ni^2 - 1/nf^2]
So there’s a greater energy difference between 1 and 2 shells
(1/1 - 1/4) vs (1/9 - 1/16)
For n=3, what are the possible quantum numbers?
n = 3 l = 0,1,2 ml = -2,-1,0,1,2 ms = +/-1/2
How does the n+l rule help you decide competitive energies of subshells?
The lower the sum of n and l value, the lower the energy
When determining electron configuration of cations, where do you remove electrons from?
Remove electrons from subshells with highest n value first
What does Hund’s rule say?
In given subshell, orbitals are filled to give max number of half filled orbitals with parallel spins
(Like avoiding sitting next to someone on a bus)
Which will be attracted to a magnet?
Paramagnetic or diamagnetic
Paramagnetic- has unpaired electrons
For each block (s,p,d,f), where will the valence electrons be?
s block- only highest s subshell (Group I And II) p block- highest s and p subshells (Group 13-18) d block- highest s and d subshells (Transition) f block- highest s and f subshells (Lanthanides and actinide)
Which will travel farther in TLC, CO2 or methanol?
CO2- least polar compounds travel further, have larger Rf
TLC has nonpolar solvent, capillary action will pull eluent up—> more soluble eluent will travel farther
Which would have highest Rf value on TLC- benzyl ester, methanol, or cyclopentanol?
Rf- distance travelled by solute/ distance travelled by nonpolar solvent
Benzyl ester (other two are polar alcohols)
Nonpolar solvent in TLC, capillary action pulls eluent up the plate- nonpolar travel farther—> larger Rf value
You’re making an artificial bone matrix. Phosphate (PO4^3-) works great, but ClO4- doesn’t work well. What’s different about these two that could cause this?
Different charges
ClO4- (perchlorate) has one negative charge
PO4^3- (phosphate) has 3 negative charges
What type of interaction is likely to be important for complex formation in antigen binding?
Hydrogen bonding!
An electron moves from the 4th to 2nd shell. Describe what happens
Energy is released
Shells farther from the nucleus will have lower ionization energies. To move to a shell closer to the nucleus (one with higher ionization energy, more stable), energy is released
Which peak is more likely for an amide hydrogen in NMR? 2 or 8
8 —> amide hydrogen would be highly deshielded by electronegative nitrogen
Deshielded = downstream (higher number)
Diethylamine is a weak base. What are the odds it will be protonated?
Not likely, weak bases not readily protonated
Describe the conditions needed for hydrolysis of amides?
Acidic or basic, but acidic easier
Basic amide hydrolysis requires strong base/heat
What does acidic hydrolysis of amides give you? What’s the reverse of this reaction?
Amides + H3O+/heat —> carboxylic acid + amine (R-NH-R)
Reverse is condensation reaction:
Carboxylic acid + amine —> amide + water
For acid-base equilibrium at constant temperature, which value is constant- pKa or [weak acid]
pKa
Acid-base equilibrium constant is Ka
What is ammonia
NH3
Has a lone pair
Weak base
Compare Lewis and bronsted bases
Lewis bases must have lone pair of electrons to donate to Lewis acid
Bronsted bases accept protons
“Forms a pi bond” =
Double bond formed
What does molecular mass relate to freezing point?
Inverse
Increase molecule mass, decrease freezing point
If CH3COONa is added to cytosol, will it become acidic or basic?
Basic
Acetate ion is a proton acceptor (conjugate base of a weak acid is itself a weak base)
What is the oxidation state of hydrogen with a metal?
What is the oxidation state of oxygen in peroxides?
Hydrogen with metal: -1
Oxygen in peroxide’s: -1
Assign oxidation state to each atom in
(NH4)2SO4
N: -3
H: +1
S: +6
O: -2
Assign oxidation state to each atom in
FeCO3
Fe: +2
C: +4
O: -2
What does a positive electric potential mean?
Species really wants to be reduced- wants electrons
Negative E*- less likely to gain electrons than hydrogen ions (Hydrogen Half-Cell is standard comparison)
True or false: a species with a negative electric potential cannot be spontaneously reduced
FALSE: can be spontaneously reduced if paired with another species with more negative electric potential
To find the cell potential (E*cell), the sum of electric potentials for two half reactions, you must reverse…
… the half reaction of the species with the lowest reduction potential and take the negative of its E value (this is the oxidation potential)
DON’T USE STOICHIOMETRY. moles don’t matter here
Compare a galvanic cell to an electrolytic cell
Galvanic- (+) cathode/ (-) anode, cell potential is always positive, can be created using any two metals (current spontaneously generated)
Electrolytic- external voltage applies to galvanic cell which forces electrons to flow in opposite direction (-) cathode/ (+) anode, cell potential is always negative, lower reduction potential species is reduced. Sum of external voltage and negative cell potential must be positive
Both- REDUCTION AT CATHODE, oxidation at anode
What is the purpose of the salt bridge in galvanic cells?
Neutralizes charge buildup; allows electron flow to continue
How does the electric potential compare for a concentration cell compared to a galvanic cell?
Electric potential of concentration cell is always 0
Always positive for galvanic cell, negative for electrolytic cell
Which has (+) which has (-) electric potential, galvanic cell and electrolytic cell
Galvanic is positive. My GALS are always POSITIVE
Electrolytic is negative. ELECTRONS are NEGATIVE
How do you find free energy change of a redox reaction?
deltaG* = -nFE*
Where n is number of moles of electrons transferred in redox rxn
F is faradays constant (the charge on one mole of electrons- 6x10^23 x 1.6x10^-19 = 9.6x10^4)
E* is electric potential
So positive electric potential = negative free energy change = spontaneous
What is the ideal gas law and give the constant in both Latm/molK and J/mol*K
PV=nRT
R = 0.08 Latm/molK or
8.3J/mol*K
What are the 2 major ideal gas law assumptions?
Gas molecules have no volume and no intermolecular forces
What are the ideal gas law STP conditions?
P = 1 atm V = 22.4 L n = 1 mole R = 0.08L*atm/mol*K or 8.3J/mol*K T = 273 K (0* C)
What is the combined gas law and why is it helpful?
P1V1/T1 = P2V2/T2
Helpful because R is constant, can be used when given same number of moles of gas
How do intermolecular forces affect real gases compared to ideal gases?
Decreases pressure
PV/nRT < 1
Due to intermolecular forces assumption—> at low temperature, pressure is decreased
How does molecular volume of real gases affect gases as compared to ideal gases?
Increased molecular volume increases volume in real gases
PV/nRT > 1
Ar high pressure, molecules are pushed close together and their actual size begins to matter- becomes comparable to the distance between them
Gas -> solid is
Deposition
What is supercritical fluid
On a phase diagram, occurs past the critical point- liquid and gas phase merge. No heat of vaporization at critical point.
True or false: different phases of substance have same heat capacities
FALSE: can be seen by differing slopes on heating curve
