Kinetics (Math)
What reaction order has a half-life that does not change regardless of the initial concentration?
a) zero-order
b) first-order
c) second-order
first-order
Which step of a reaction mechanism determines the rate?
a) slow-step
b) fast-step
c) all the steps
slow-step
During oxidation, electrons are _____.
OIL = Oxidation is Loss of electrons
Name the (7) strong acids.
HCl, HI, HBr, H2SO4, HNO3, HClO4, HClO3
Identify which is the precipitation reaction and which is the dissociation reaction?
a) Ca(OH)2 ⇌ Ca2+ + 2 OH-
b) Ca2+ + 2 OH- ⇌ Ca(OH)2
Dissolution (s) ⇌ (aq) + (aq)
Precipitation (aq) + (aq) ⇌ (s)
What are the units for the rate constant (baby k) for a second-order reaction?
1/M⋅s
How does a catalyst speed up a reaction?
(two specific ways)
1) reduce the activation energy (hump)
2) help orient molecules for proper collision
When adding two half-reactions together, the number of _____ must be the same on both sides to cancel out.
Electrons in must match electrons out.
The short bond length makes the proton unlikely to leave.
What is the equilibrium expression (Keq) for the following dissolution:
Al(OH)3 ⇌ Al3+ + 3 OH-
[Al3+][OH-]3/ 1
(denominator removed because solid)
If a graph of ln[A] vs time produces a linear graph, then the reaction is _____ order. But if a linear graph is produced when 1/[A] is graphed, it is _____order.
first order = ln[A]
second order = 1/[A] = [A]-1
____ are produced in an early step and used up in a later step, while _____ are used up in an earlier step, and produced again in a later step.
Intermediates are produced then consumed.
Catalysts are consumed and re-spawn.
Generally oxygen has a redox number (oxidation state) of -2, except in it's peroxide form when it is _____.
Ex: H2O2
O is generally -2 but can be -1
Vinegar (H3C-COOH) has 4 Hydrogens, but only one of them is acidic. Identify which hydrogen is most likely to be donated and why.
The H on the end of the carboxyl group. Without the H present, the COO- can resonate. Resonating creates stability, so this is the desired state.
To calculate the Ksp of a salt when it dissociates into 2 ions would be...
a) 2x2
b) 2x
c) x2
d) √x
K = [x][x] = x2
If a 20 gram sample of a radioactive isotope has a half-life of 2 days, how many days will it take to reach a mass of 5 grams?
20→ 10→ 5
2 half-lives (x2) = 4 days
If a reaction profile has a large activation energy, the reaction will be ______ (slow/fast)
Large hump = not happening often = "slow"
Generally hydrogen has a redox number (oxidation state) of +1, except when bonded to ______ and becomes -1.
H bonded to metal
H becomes -1 and metal becomes +1
Buffers have 2 general components. What are they?
1) Something weak (like a weak acid)
2) It's conjugate (its conjugate base)
To calculate the Ksp of a salt when it dissociates into 3 ions would be...
a) 3x3
b) 3x2
c) 4x3
d) x2
K = [x][2x]2 = 4x3
What is the rate law for the elementary reaction?
A + 2B → C
rate = k[A]1[B]2
How is the rate constant (baby k) in kinetics different than the equilibrium constant (Keq aka Kanye)? Describe them both.
k is lowercase, Keq is uppercase, both numerical
baby k is how much surface area, etc contribute
baby k has units that change every problem
Keq is a unitless ratio of the pile amounts
Is the following a redox reaction?
C3H8 + 5 O2 → 3 CO2 + 4 H2O
Which of the following weak acids is the strongest?
HCN (pka=9.2)
HOCOOH (pKa=6.4)
HNH2 (pKa=35.0)
Big Ka = small pKa = strong acid
What two criteria make a chemical be highly soluble?
1) the 1+ ions are always soluble
2) nitrates (NO3-) are always soluble