My Old GCHEM + OCHEM flashcards
Are intermediates allowed to appear in the rate law?
No.
Name the 2 different “forms” of the gas constant. Also, name the conditions at STP.
R = 0.0821 (L atm) / (mol K)
R = 8.314 J / (mol K), (where P is in Pascals and V is in m3)
STP: 0° C , 1 atm pressure
Are S° values smaller or larger for more complex molecules?
S° values are larger for more complex molecules.
What is Henry’s law?
Solubility = kP
Solubility = molar solubility of a gas in a liquid.
k = constant (specific to each gas and temp).
P = partial pressure of the gas over the solution.
What is the equation that relates Kp to Kc?
Kp = Kc (RT)Δn
Δn = change in number of moles of gas.
What is the “normal” form of the Arrhenius equation?
k = Ae (–Ea)/(RT)
A is the frequency factor
e is the mathematical e
Ea is the activation energy
k is the rate constant
What is the integrated rate law for a first order reaction?
ln [A]t = –kt + ln [A]0
What happens halfway to the equivalence point of a titration?
pH = pKa
What is the equation for osmotic pressure?
Π = iMRT
Π is the osmotic pressure.
i is the van’t Hoff factor.
M is the molarity.
R is the gas constant.
T is the temperature.
Are catalysts allowed to appear in the rate law?
Yes.
What are the units of k for a second order reaction?
1 / (M sec)
What is ΔG°f ?
ΔG°f is the standard free energy of formation.
ΔG°f is zero for an element in its most stable form at 25°C.
What are the units of k for a zero order reaction?
M / sec
What is the purpose of the Arrhenius equation?
It lets you calculate the activation energy of a reaction, based on the rate constants at two different temperatures.
How do the following compounds compare in terms of acidity:
HClO, HClO2, HClO3, and HClO4
Why?
Low Acidity HClO < HClO2 < HClO3 < HClO4 High Acidity
The reason is due to oxidation number. HClO4 has the most highly oxidized atom bonded to the oxygen with the proton.
How does entropy change as temperature increases?
The entropy of a substance increases with increasing temperature.
What is Graham’s law of effusion for two gases?
What does the symbol D mean in chemistry? What can be calculated from it, and how?
D is the bond dissociation energy.
D is always positive, because energy must always be supplied in order to break a bond.
ΔH°rxn = D(reactant bonds) – D(product bonds)
Define critical point.
The spot on a phase diagram where the liquid/gas boundary line abruptly ends (supercritical fluid is formed above this line).
What is the second law of thermodynamics?
In any spontaneous process, the total entropy of a system and its surroundings always increases.
What is the “linear” form of the Arrhenius equation?
ln k = (-Ea/R) (1/T) + ln A
y = m x + b
A is the frequency factor
Ea is the activation energy
k is the rate constant
What is the rate law for a first order reaction?
Rate = k [A]
What is the half-life of a zero order reaction?
t1/2 = [A]0 / (2k)
What is the Clausius-Clapeyron equation?
What is it useful for?
ln Pvap = ( –ΔHvap / R ) ( 1 / T ) + C
y = m x + b
Pvap is the vapor pressure.
ΔHvap is the heat of vaporization.
C is a constant (not related to heat capacity).
This equation lets you calculate ΔHvap if Pvap is known at two different temperatures.
What is Raoult’s law?
PA = XAPA°
PA is the partial pressure exerted by component A in the solution.
PA° is the vapor pressure of pure A.
XA is the mole fraction of A in the solution.
What is the first law of thermodynamics?
The total internal energy E of an isolated system is constant.
What is the link (in equation form) between kinetics and equilibrium?
Kc = (kfor) / (krev)
What is the advantage of using molality?
It doesn’t depend on temperature, like molarity does.
What is the equation for boiling point elevation and freezing point depression?
ΔTb = Kb m i
ΔTf = Kf m i
ΔT is the change in boiling or freezing point.
Kb is the molal boiling point elevation constant.
m is the molality of the solution.
i is the van’t Hoff factor (mol in solution / mol dissolved).
Name all the units of pressure, and what they are equal to at standard atmospheric pressure.
1 atm = 760 mm Hg
760 mm Hg = 760 torr
1 atm = 101,325 Pa (N / m2)
1 bar = 100,000 Pa
What happens when AgCl is added to pure water? What happens when NH3 is added?
AgCl is insoluble in pure water, but dissolves when NH3 is added. This happens because the Ag+ forms a complex ion (via coordinate covalent bonds) with the NH3.
Define IP.
IP = Ion Product. It is basically Q for a solubility equilibrium.
Define ΔS°.
ΔS° is the standard entropy of reaction.
ΔS° = S°products – S°reactants
What is the relationship between ΔG, ΔG°, K, and Q?
ΔG = ΔG° + RT lnQ
At equilibrium, ΔG = 0 and K = Q, so:
ΔG° = –RT lnK