Chem/Ochem Review Flashcards
NADH/NADPH are what type of agents
Reducing
What does a hydrolase do?
Cuts with water
A dehydrogenase…
dehydrates-takes away a hydrogen
What type of bonding occurs between DNA base pairs?
Hydrogen and Van Der Waals
Kinetically favorable
low activation energy
Thermodynamically favorable
products have lower energy than reactants
G and C pair between ____ Hydrogen bonds, and A and T pair between ____ Hydrogen bonds.
3, 2
Hydride
Anion of Hydrogen: H-
Gibbs free energy equation
^G=^H-T^S
^H=enthalpy change
^S=entropy change
Blood flow equation
Q=AV Q=flow rate, A=cross sectional area, V=velocity of fluid
Velocity changes ____ m/s while airborn
10m/s
Average velocity is equal to
Vf+Vi/2
Deuterium
Deuterium is one of two stable isotopes of hydrogen. The nucleus of deuterium, called a deuteron, contains one proton and one neutron, whereas the far more common protium has no neutron in the nucleus. (is uncharged).
Photon
When emitted, energy is released.
Henderson-Hasselbalch eq
pH = pKa - log([HA]/[A-])
for every 1.0 unit difference between the pKa and the pH, the ratio of acid to base (or base to acid) will change by a factor of 10 (and following that trend, for every 2 units it would differ by a factor of 100, for every 3 units by a factor of 1,000 and so on).
Pka to PH
If PKa -> PH, equation shifts to right, acids.
If Pka Acids
Le Chatelier’s Principle
The attempt for an equation to restore equilibrium.
in CO2 + H2O ↔ HCO3- + H+, if the [H+] increased, the equation would shift left to balance and more CO2 would result.
** Equilibrium expressions are written as products over reactants.
Color spectrum
390nm————————–700nm
violet, greens, blues, etc, red
induced-fit mechanism
proposes that the enzyme stabilizes the transition state of the substrate, causing a reduction in the activation energy of the transition state.
lock and key mechanism
In this analogy, the lock is the enzyme and the key is the substrate. Only the correctly sized key (substrate) fits into the key hole (active site) of the lock (enzyme).
Michaelis-Menten kinetics equation:
V0 = Vmax[S]/(KM + [S])
Sucrose:
Formed by 1 glucose and 1 fructose. Glucose forms a 6 membered ring while fructose forms a 5 membered ring
Oligomer:
A few monomer units combined, but not unlimited like a “polymer”
Oxidation/Reduction:
If something is oxidized (loss of electrons) then it is a reducing agent. Vice versa
D (dextrorotary):
L
D: Rotates light clockwise.
L: Rotates light counterclockwise
Metals:
THINK OF METALS AS: larger atoms with loosely held electrons. Metals “like” to lose
electrons and form positive ions. They are lustrous, ductile, malleable and excellent conductors of both
heat and electricity. They are involved in ionic bonds with nonmetals. Are good reducing agents.
Have lower electronegativities.
Non Metals:
THINK OF NON-METALS AS: smaller atoms with tightly held electrons. Non-metals
“like” to gain electrons and form negative ions. They have lower melting points than metals, and form
covalent bonds with non-metals. Most of the O-Chem stuff involves non-metals. Form oxides that are acidic.
Are good oxidizing agents.
The smaller the atom, the ___:
more electronegative, have a higher ionization energy, greater electron affinity and less metallic character than a larger atom.
Electron affinity:
the amount of energy released or spent when an electron is added to a neutral atom or molecule in the gaseous state to form a negative ion.
Electronegativity:
a measure of the tendency of an atom to attract a bonding pair of electrons.
Ionization energy:
the amount of energy required to remove the most loosely bound electron, the valence electron, of an isolated gaseous atom to form a cation. (+)
Work Function:
Bombarding certain metals with energy can cause the ejection of an electron from their outermost shell (i.e., valence electron). The work function
refers specifically to valence electrons being ejected from the surface of a solid metal. If the energy
added is less than the work function, the electron won’t be ejected. If it is greater than the work function, the excess energy will be transferred into the kinetic energy of the ejected
electron.
KE = E – φ , E = hf
Electron Emission:
One of the most important take-home messages is that more INTENSE light [i.e., same wavelength, but more photons striking the metal per second] does NOT increase the KE of ejected photons, but DOES increase the number of photons ejected. Meanwhile, changing to a higher frequency light [i.e., blue light replacing red light] DOES increase the KE of the ejected electrons [as long as the work function has been exceeded].)
Half life:
The half-life of a substance (t1/2) is the amount of time required for exactly one-half of the mass of that substance to disappear due to radioactive decay.
Alpha decay:
The loss of one He nucleus, which has a mass number of 4 and atomic number of 2.
Beta Decay:
A neutron is changed into a proton with the ejection of an electron.
Electron capture:
A proton is changed into a neutron via capture of an electron
Ionic character:
The amount of ionic bonding going on between two atoms. Max amount would be between Florine and Francium, due to largest difference in electronegativity. C-C has almost none.
Condosity:
The “condosity” of a solution is the concentration (molarity) of an NaCl solution that will conduct electricity exactly as well as the solution in question
7 strong acids:
HCl, HBr, HI, HNO3, HClO3, HClO4, and H2SO4
Bond Strength:
Energy is always REQUIRED to break a bond. Energy is always RELEASED when a bond is formed Stable compounds (e.g., N2) have HIGH bond energies. Unstable compounds (e.g., ATP) have LOW bond energies
Heat of combustion:
the amount of energy released when a molecule is combusted with oxygen. All covalent bonds are broken and reformed in a radical reaction. The higher the energy of the molecule (i.e., less stable) the higher the heat of combustion.
Coordinate covalent bond:
A covalent bond in which both electrons shared in the bond are donated by one atom. In most cases, more than one of these “donor” molecules surround and bind a single “recipient” molecule. The donor molecule must have a lone pair and the recipient molecule must have an empty orbital
Emperical formula vs molecular formula:
Molecular formulas tell you how many atoms of each element are in a compound, and empirical formulas tell you the simplest or most reduced ratio of elements in a compound. If a compound’s molecular formula cannot be reduced any more, then the empirical formula is the same as the molecular formula
Percent mass:
(mass of one element/total mass of the compound)(100%)
hydroxide, nitrate, nitrite, chlorate,
chlorite, hypochlorite, perchlorate, carbonate, bicarbonate, ammonium, sulfate, phosphate,
manganite, permanganate, and cyanide
Hydroxide is OH- nitrate is NO3- nitrite is NO2- chorate is ClO3- perchlorate is ClO4- chlorite is ClO2- hypochlorite is ClO- carbonate is CO32- bicarbonate is HCO3- ammonia is NH3 ammonium is NH4+ sulfate is SO42- phosphate is PO43- manganate is MnO42- permanganate is MnO4- cyanide is CN-
Combustion reaction:
Combustion reactions take place when a compound containing carbon and hydrogen reacts with oxygen to make water vapor, carbon dioxide, and heat.
CₘHₙ + O₂ → CO₂ + H₂O
Synthesis reaction:
simple compounds are combined to make a more complex one.
2 Na + Cl₂ →2 NaCl
decomposition reaction
where a molecule breaks apart into simpler ones.
2 H₂O₂ → 2 H₂O + O₂
Single displacement reaction:
when a pure element switches places with an element in a chemical compound.
A + BC → B + AC
Acid-base reaction.
If you combine an acid with a base, you’ll get water and something else.
HA + BOH →BA + H₂O
Percentage Yield
Percentage Yield = mass of Actual Yield x 100%
mass of Theoretical Yield
How can you increase yield?
1) Start with more reactants (has to include more of limiting reagent)
2) Shift the equilibrium to the right using one of the actions described by Le Chatelier’s Principle
Decrease in Pressure:
Equation will shift from low moles to high moles
Kinetics:
Kinetics is the study of reaction rate. In other words, how quickly the reaction proceeds. This is usually measured in terms of how fast the reactants disappear by tracking changes in the concentration of the reactants as a function of time. rate, catalysts, enzymes, energy of activation, reaction order, and transition state.
Thermodynamics:
the thermodynamics of a reaction reflect the potential reactivity (for example, given infinite reaction time) and includes all measurements of energy flow and relative stability. Keq, Q, entropy, enthalpy, Gibbs free energy, “favorability,” “spontaneity,” “differences in energy between products vs. reactants,” and yield
K
Q>K , then the reaction favors the reactants.
K>Q
Then reaction favors products. ->
Le Chatelier Increase in pressure:
Increasing the pressure on a gas reaction shifts the position of equilibrium towards the side with fewer molecules.
Kinetics:
Kinetics is the study of reaction rate. In other words, how quickly the reaction proceeds. This is usually measured in terms of how fast the reactants disappear by tracking changes in the concentration of the reactants as a function of time
Thermodynamics:
the thermodynamics of a reaction reflect the potential reactivity (for example, given infinite reaction time) and includes all measurements of energy flow and relative stability.
Rate:
is measured as the change in molarity (M) of the reactants per second (M/s)
Rate order graphs:
These graphs will only be linear when the reaction has only a single reactant, OR when it is part of a multiple-reactant reaction where the rate is independent of ALL the other reactants
Zero Order: [A] vs. time is linear
First Order: ln[A] vs. time is linear
Second Order: 1/[A] vs. time is linear
Catalysts don’t affect:
They do NOT change the equilibrium, Keq, enthalpy change, entropy change, Gibbs free energy, or any other thermodynamic properties.
Quantum numbers:
-The azimuthal quantum number describes
the subshell where the electron is located.
-The magnetic quantum number specifies
which of the orbitals holds the electron.
-The electron spin quantum number
differentiates between two electrons in the
same orbital.
electron configuration of chlorine in NaCl.
configuration of the chloride ion, which will be the same as the nearest noble gas.
Determining combustability:
+1 for each carbon, -.5 for each Oxygen
Radiation:
Electromagnetic waves emitted from a hot body into the surrounding environment.
▪ Light colors radiate and absorb less
▪ Dark colors radiate and absorb more
Heat capacity:
The amount of energy (Joules or Calories) a SYSTEM must absorb to give a unit change in
temperature (J/K or cal/˚C).
o Formula, where C is the heat capacity, q is heat (or other energy) and T is temperature:
▪ C = q/∆T
Specific heat capacity:
describes energy absorption for one
individual substance only and is defined per unit mass.
q = mc∆T
Calorimeters:
Device used to calculate enthalpy change (∆H).
Coffee cup: q=mc∆T Provides constant pressure (atmospheric)
Bomb: q = C∆T Provides constant volume
PV Work
Work is energy transfer via a force (physics), or via a change in volume at constant pressure
(chemistry). PV Work = P∆V (requires constant pressure, any change in volume tells you there is pv work)
The First Law of Thermodynamics:
Energy can neither be created nor destroyed.
Isolated system: heat nor mass can be transferred, any changes are considered part of system
closed system: ∆E = q + w, q=heat change w=work done, not included as part of system
The second law of Thermodynamics:
o Heat cannot be changed completely into work in a cyclical process.
o Entropy in an isolated system can never decrease.
The Third Law of Thermodynamics:
o Pure crystalline substances at absolute zero have an entropy of zero. (would take infinite number of steps)
Temperature:
a measure of the average kinetic energy of the molecules in a substance.
Boltzmann’s constant:
KE = 3/2kBT
Celsius to Kelvin:
C + 273.15
Enthalpy
Enthalpy = the energy contained within chemical bonds (Joules) we can calculate ∆H for a reaction (i.e., the change in enthalpy) by finding the difference in total
bond energy between the products and the reactants.
entropy:
▪ positive ∆S = increased randomness, and thus more energy available to do work.
▪ negative ∆S = decreased randomness, and thus less energy available to do work.
entropy is represented by the capital letter S, and it is a thermodynamic function that describes the randomness and disorder of molecules based on the number of different arrangements available to them in a given system or reaction.
Gibbs free energy:
∆G = ∆H-T∆S
∆G = -RTlnK
∆G = the amount of “free” or “useful” energy
available to do work
▪ negative ∆G = Spontaneous process; free energy available to do work.
▪ positive ∆G = Non-spontaneous process; no free energy available; energy is required.
Isobaric
means constant pressure.
Isotherm
means no heat exchange (i.e., constant
temperature).
Bronsted-Lowry:
Acids donate protons (H+); bases accept protons (H+).
Lewis:
Acids accept a pair of electrons; bases donate
a pair of electrons.
Amphoteric
substances can act as either an acid or a base (e.g., H2O).
pH formula:
pH = -log[H+] or [OH-]
..A solution with a pH of 2 has [H+] = 10-2
while a solution of pH 4 has [H+] = 10-4
Acid Dissociation Equation:
HA + H2O H3O+ + A-
Ka = [H+][A-]/[HA]
Ionization of water:
Addition of acid lowers PH, addition of base highers PH
At 25°C, Kw = Ka*Kb
H2O + H2O H3O+ + OH
the addition of either an acid or a base shifts the equilibrium for the ionization of water to the left
Strong Acids:
HI, HBr, HCl, HNO3, HClO4, HClO3, H2SO4, H3O+
NOT HF
Strong Bases:
Group 1A hyrdroxides ( NaOH, KOH, etc.), NH2-, H-,
Ca(OH)2, Sr(OH)2, Ba(OH)2, Na2O, CaO.
Titration:
“A strong base is titrated with a strong acid”
Base is in beaker, Analyte Acid is being added, titrant
What is a buffer made up of?
A buffer solution contains a weak acid and weak base, often the conjugates of each other. In a buffer
there is an equilibrium between a weak acid and its conjugate base, or between a weak base and its
conjugate acid.
Henderson-Hasselbalch equation
pH = pKa + log[A-]/[HA]
Resonance affect on acidity:
More resonance = greater acidity
When ranking acidity:
Look at stability of conjugate base
Why do less stable molecules release more energy in a combustion reaction?
the energy of the products is always going to be the same (i.e., the energy of CO2 + H2O). Therefore, the higher the energy of the reactant the greater will be
the difference in energy between the reactant and the combustion products.
Formula for formal charge:
Formal charge = Valence - assigned (2 for lone pair, 1 for each bond)
