General Chemistry Flashcards
What is a zero-order reaction? If I add twice the amount of reactants, what will happen to the rate of the reaction?
zero order reaction is a reaction where the [rxnt] doesn’t affect the rate of reaction.
adding twice the amount doesn’t matter because shits not gonna change
What is a first order reaction? If I add twice the amount of reactants, what will happen to the rate of the reaction? What situation should I be wary of?
the rate of the reaction only depends on ONE rxnt
If I add twice the amount of ONE reactant, it will increase the rate of reaction by TWO times (linear)
CAVEAT: Even if there are two reactants, don’t automatically think it’s 2nd order. If the question says shit changes for one linearly but doesn’t for the other reaction, that is a first order reaction!!
What is a second order reaction? If I add twice the amount of reactants, what will happen to the rate of the reaction? What is a situation that I should be wary of?
the rate of the reaction only depends on TWO rxnts
If A and B are my reactants, it can go two ways (exponential):
[A]^2 OR [B]^2 → QUADRUPLE rate of rxn
2[A][B] → QUADRUPLE rate of rxn
CAVEAT: Even if there are two reactants that individually are first order reactions, generally do NOT use NET RXN to determine rxn order. The fact that those two reactants DID affect the rate MEANS that the reaction as a WHOLE is 2nd order. REMEMBER THE DEFINITIONS!!
What are the two situations in reactions that indicate INCREASED entropy?
- If the moles (coeff) in pdt > moles in rxnt (ie. decomposition)
- change in phases in increasing disorder from rxnt → pdt (ie. s → g, s→ l, l → g, s → g)
List 2 steps in which you can calculate the approximate change in enthalpy if given a table with delta H formation data. (Hint: What law does delta H formation remind you of? What is a caveat you have to remember?)
- write the balanced rxn if not provided
- HESS’S LAW = sum(delta Hf pdts) - sum(delta Hf rxnts)
CAVEAT: ELEMENTS in their standard states have Hf = 0!!
0th law of thermodynamics
2 bodies in thermal equilibrium have the same temp
2nd law of thermodynamics
↑ entropy in a spontaneous process
3rd law of thermodynamics (Hint: related with the 2nd)
ENTROPY of PURE crystalline compounds at 0 K is ZERO!
How do you know if your compound is solid (ie. a precipitate)
If they contain minerals (transition metals) like Fe, Cu, Ag, Al, etc. that act as metal cations and anions which are usually polyatomic (ie. SO42-, PO43-, OH-, Cl-, etc.)
ie. Ag2SO4 is solid!!
What is the equation of the rate law of an rxn? What does each of the components mean?
rate law = k[rxnt(s) of the SLOWEST (rate-limiting) step]^coeff
k = equilibrium constant rxnt(s) = MAKE SURE all reactants you include here are ONLY in the slow step and not in OTHER steps (if multiple rxns are given) coeff = # moles of the rxnt in slow step → can determine the ORDER of rxn (0th = k, 1st = k[A], 2nd = k[A]^2)
In a graph that shows the reaction coordinate (time elapsed essentially) vs the free energy, how are intermediates signified?
they are the local minima between 2 transition states!
If a question asks whether a reaction coordinate vs free energy graph is indicating enzymatic activity, how do you confirm that it is?
you NEED to have another reference curve (non-enzyme vs enzyme)
→ if you only see ONE curve, you CANNOT make the assumption that enzymatic activity is present!
If they said solid platinum is the catalyst, would the statement “solid platinum increases the rate of the reaction better than its powder form” support the fact that solid platinum is the catalyst? Why or why not?
NO b/c powder form is better (↑ SA = ↑ rxn rate). Hence, the argument is INCONSISTENT with solid platinum being a catalyst
FOR THESE QUESTIONS: just objectively cross out anything that is OBJECTIVELY FALSE!
How do you calculate Q? What if Q is less than, greater than, or equal to Keq?
Q = [mole of pdts] / [mole of rxnts]
Q < Keq = forward
Q > Keq = reverse
Q = Keq = equilibrium
What is the temperature where particles can’t move in K? C°?
0 K
-273 °C
In terms of P and T, what are the conditions where particles are behaving LEAST like the ideal gases?
HIGH pressure
LOW temperature
combined gas law
PV/T = constant
combo of Boyles, Charles, and Guy-Lussac’s law
Henry’s Law
↑ partial pressure of gas = ↑ gas dissolved in liquid
amount of gas dissolved in liquid is PROPORTIONAL to the partial pressure of the gas ABOVE the liquid
Dalton’s law of partial pressure
partial pressure of gas in container = mole fraction of gas x Ptot
What are the P, T, and V for 1 mol in STP conditions (gas)? Is STP the same thing as standard conditions? If not, what is the temp in standard conditions?
P = 1 atm
T = 0 °C (273 K)
1 mol of gas = 22.4 L
STP is NOT the same thing as standard conditions. In standard conditions, the temp is 25 °C (298 K)
According to the ideal gas law (PV = nRT), what is the approximate volume of 16 g helium in STP conditions?
STP conditions → 1 mol gas = 22.4 L
16g He / (4 g He) = 4 mol He
4 mol He x 22.4 L ~ 88 L!!
CAVEAT: the PV=nRT equation wasn’t even NEEDED to solve this problem. the reason why they added this is because the ideal gas law happens in STP conditions. Hence, this equation is a DISTRACTOR!! BE AWARE OF THIS!!
isomerase
catalyze conversion of one CONFIGURATIONAL isomer to another (cis ↔ trans)
What are constitutional (structural) isomers based on their molecular formula (atoms), connectivity, etc.?
same molecular formula
DIFFERENT connectivity
What are conformational isomers based on their molecular formula (atoms), connectivity, etc.? Is it a stereoisomer?
same molecular formula
same connectivity
DIFFER in rotation about a single bond
Yes
What are configurational isomers based on their molecular formula (atoms), connectivity, etc.? Is it a stereoisomer?
same molecular formula
same connectivity
DIFFER in chirality or w/ respect to a double bond (CIS VS TRANS SHIT!)
Yes
What are enantiomers based on the number of chiral centers and stereochemistry? Is it a geometric or optical isomer? Is it a subset of configurational or conformational isomer?
has 1 or more chiral centers
ALL chiral centers must be stereoisomers of each other (mirror image)
optical
configurational
What are diastereomers based on the number of chiral centers and stereochemistry? Is it a geometric or optical isomer? Is it a subset of configurational or conformational isomer?
has 2 or more chiral centers
differ in stereochemistry in AT LEAST one chiral center, but NOT ALL chiral centers!
optical
configurational
What are epimers based on the number of chiral centers and stereochemistry?
2 or more chiral centers
stereochemistry must differ in ONLY 1 chiral center!
T/F: molecules with 1 chiral center could be enantiomers, diastereomers, or epimers.
FALSE
By definition, diastereomers and epimers have 2 OR MORE chiral centers. If the singular chiral center differs in stereochemistry, it will automatically be an enantiomer!
Formal charge equation
VE - NBE (# non-bonded e-) - #bonds
What is an anomeric carbon? When numbering carbons, what is the anomeric carbon designated as?
carbonyl carbon in carbohydrates
C1
T/F: Trans (E) isomer is MORE stable than Cis (Z) isomer
TRUE
trans is more stable because ↓ steric hindrance of methyl groups (for example) → ↑ stability of molecule overall
“CZET” → Cis/Z and E/Trans
In a ring format (not linear), how can you tell whether it is in α or ß configuration? What kind of stereoisomers are they and are on which carbon?
α has OH at the bottom, ß has OH at the top (“alphas support (need to be on the bottom to push up) and betas get carried up”)
epimers at anomeric carbon
Galvanic vs Electrolytic cells in terms of what charge the anode is, what charge the cathode is, the spontaneity of the rxn, and whether it requires an external voltage source
Galvanic vs Electrolytic cells (in this order, respectively)
Anode: negative VS positive
Cathode: positive VS negative
Spontaneity: spontaneous VS non-spontaneous
Ext. V source: does NOT require VS DOES require
atomic number vs mass number vs nucleon
atomic number = protons only
mass number = protons + neutrons
nucleon = can either be a proton or neutron (shit inside the nucleus, basically)
T/F: The actual mass of any non-H nucleus is slightly larger than the sum of masses of its protons and neutrons.
FALSE → slightly SMALLER b/c of the mass defect (the amount of mass converted to binding energy, which is the energy needed to bind some P and N within the nucleus)
mass defect
the amount of mass converted to binding energy, which is the energy needed to bind some nucleons within the nucleus
Another way to think about this is the difference between the mass of the unbonded nucleons (more energy = more mass) and the mass of the bonded nucleons within the nucleus
By separating and analyzing compound fragments and comparing them to known reference values, mass spectroscopy can be used to determine:
I. Total molecular mass
II. elemental composition
III. molecular structure
ALL OF THE ABOVE
its the shit that has graphs w/ long lines w/ #s at the top of them
Halogens have
I. high ENs
II. not naturally found in their elemental state
III. gases at standard conditions
I and II (as halides (ions) or diatomic molecules)
g → F2, Cl2
l → Br2
s → I2
transition elements have ___ melting points, ___ ENs, ___ IEs, and ___ oxidation state(s).
high
low
LOW
multiple
representative elements
groups 1, 2, and 13-18
Elements in Group 16 that have essential biological functions include I. O II. Se III. Po IV. S
I, II, IV (sulfur = component in certain AAs + vitamins)
Po is toxic!
Avogadro’s number
1 mol = 6.02 x 10^23 atoms
T/F: cations have larger radii than parent atoms and anions have smaller radii than parent atoms
FALSE
Cations have SMALLER radii and anions have LARGER radii
→ cations have less e- → ↓ electron repulsion = stronger nuclei → ↓ atomic radius since e- are pulled in tighter
Isotopes differ in
I. #neutrons
II. #protons
III. reactivity
I ONLY!
alkali metals tend to ___ 1 e-
LOSE!
They HAVE 1 e-, so it’s easier to LOSE!
molality vs molarity in terms of what the ratios are and their units
Ratio
Molality: # moles of solute / mass of solvent
Molarity: # moles of solute / volume of solvent
Units
Molality: mol/kg
Molarity: mol/L
T/F: When e- is taken away, the electric potential energy is decreased
FALSE!
U = kQq / r, and conventionally Q and q are opp signs so U is negative!
take e- away → ↑ r → U becomes less negative → more + U → ↑ U
T/F: When e- is added to a neutral atom, energy is absorbed, making it a less stable state.
FALSE
e- goes from high → low energy state when this happens since e- is bought CLOSER to the positive nucleus!
HENCE: energy RELEASED → MORE STABLE state
polyatomic cation vs polyatomic anion
a polyatomic ion is an ion with 2 or more atoms. Hence cation is positive whereas anion is negative
ie. H3O+ = polyatomic cation; SO42- (sulfate) = polyatomic anion
autoionization
rxn between molecules of the SAME substance to produce ions
ie. H2O + H2O ↔ H3O+ + OH-
triprotic acid and an example
an acid that has 3 dissociable Hs that are successively lost
Ie. phosphoric acid (ie. H3PO4)
oxalic acid chemical formula, mono/di/triprotic?, strong/weak acid?
H2C2O4
diprotic
weak
carbonic acid chemical formula, mono/di/triprotic?, strong/weak acid?
H2CO3
diprotic
weak
sulfuric acid vs sulfurous acid chemical formula, mono/di/triprotic?, strong/weak acid?
H2SO4 vs H2SO3 (-ic has 1 MORE O than -ous)
diprotic
strong vs weak
At STP, Kw is a product of what and its exponent is?
Kw = Ka x Kb = 10^-14
At STP, Kw = [H3O+][OH-] = 10^-14. But at lower temperatures, do we see and ↑ or ↓ in Kw and pH?
↓ Kw b/c since less heat added → reverse rxn favored → fewer H3O+ and OH- will be made
↑ pH since ↓ [H3O+] = ↓ [H+]
List the top 7 STRONG acids
HCl, HBr, HI
HClO3, HClO4
HNO3, H2SO4
List the top 7 WEAK acids
HCOOH, CH3COOH, C6H5COOH
C2H2O4
HF, HNO2, H2SO3
formic vs acetic vs benzoic acid, strong/weak acids?
HCOOH vs CH3COOH vs C6H5COOH
ALL WEAK ACIDS!!
nitric acid vs nitrous acid chemical formula, mono/di/triprotic?, strong/weak acid?
HNO3 vs HNO2 (-ic has one MORE oxygen than -ous)
monoprotic
strong vs weak
List the top 8 STRONG bases
LiOH, NaOH, KOH, RbOH, CsOH
Ca(OH)2, Sr(OH)2, Ba(OH)2
List the top 8 WEAK bases
NH3 (ammonia)
Pb(OH)2, Cu(OH)2, Zn(OH)2
Al(OH)3, Fe(OH)3
CH3NH2 (methylamine), N(CH3)3 (trimethylamine)
What are hydration spheres? What do they allow?
When salt deionizes into ions, the cation is surrounded by the partial negative ion (O) and the anion is surrounded by the partial positive ion (H)
allows EVEN distribution of ionic compound in water
T/F: Alkali metals are combined with other elements in nature because they are more reactive than cations. If false, explain why
FALSE
LESS reactive as cations than neutral form (has 1 VE)
their 1 VE is more weakly bound than those in inner shells
What group has the highest first IE? Lowest?
noble gases have highest first IEs b/c of octet rule
alkali metals have lowest first IEs
What is the level of saturation when the ion product (IP) is:
- IP < Ksp
- IP > Ksp
- IP = Ksp
IP < Ksp = unsaturated
IP > Ksp = supersaturated
IP = Ksp = saturated
common ion effect
solubility of ionic precipitate decreases with the addition of an ion common with precipitate
H2S (aq) ↔ 2 H+ (aq) + S2- (aq)
If the concentration to precipitate ZnS = 1.6 x 10^-21 M, what will prevent this precipitate from happening?
a) add more HCl (l)
b) add more H2S (g)
A
add more HCl → ↑ [H+] → shift rxn to reverse → prevent H2S from dissociating into S2- (which is the common ion that is needed in both ZnS and H2S, the original compound)
