Chem Lesson 2: 12.4 - 12.6 Flashcards
Integrated Rate Laws
Let’s us see the concentration of a reactant at any given time.
Integrated Rate Law (Zero Order Equation)
[A]f = [A]o - kt
Integrated Rate Law (First Order Equation)
ln[A] = ln[A]o - kt
Integrated Rate Law (Second Order Equation)
1/[A] = 1/[A]o + kt
K Unit for Zero Order
M^1t^-1
K Unit for First Order
t^-1
K Unit for Second Order
M^-1t^-1
Yes or No - Does the half life of a first order reaction depend on the initial concentration.
No
Half Life - Zero Order Reaction
[Ao] / 2k
Half Life - First Order Reaction (Mysterio)
ln*2 / k
0.693 / k
Half Life - Second Order Reaction
1 / (k * [Ao])
K Unit for Third Order
M^-2 t^-1
Decaying Order
First Order
How to cancel Ln out?
Raise both sides to the e^ power.
100% in Integer form
100
100% in Fraction form
1
Collision Theory
Requirements that need to take place for a chemical reaction to occur:
1. Collision (must collide).
2. Proper orientation.
3. Sufficient energy (to get over activation barrier).
Arrhenius Equation (def)
Relates activation energy and the rate constant (k).
Arrhenius Equation (Exponential equation - before two point)
k = Ae^-Ea/RT
Arrhenius Equation (Y = mx + b)
ln(k) = - Ea/R(1/T) + lnA
Frequency Factor (A) - Arrhenius Equation (Definition for A)
Fraction of molecules that have the proper orientation when they collide.
R (energy constant value for rate law)
8.314 J/mol * k
Transition states
Short lived molecules formed in between reactants turning into products.
(Forms when E,a is met - top point of graph).
(e^-Ea/RT) def in Arrenius Equation
Fraction of molecules that have enough energy to get over the activation energy barrier.
Activation Energy (E,a)
Minimum amount of energy needed to make products during a collision.
E,a (graphical method slope equation)
ea = -(slope)(R)
Two Point Arrhenius Formula (two temps &/or two Rate Constants)
ln(k1/k2) = Ea/R * (1/T^2 - 1/T^1)
Ea Unit
J mol^-1
or
J/mol
C —> K
C + 273.15
Frequency Factor (A Equation) - Find K
k = Ae^-Ea/RT
Frequency Factor (A) Unit
Same as K values
Reaction Mechanism
Provides precise details of the step-by-step process by which a reaction occurs.
Elementary reaction
Each step in a reaction mechanism.
Intermediate
Species that are produced in one step and used up in another step. (Appears on product side first then cancels out).
Molecularity (Elementary Reaction)
Number of reactant entities (atoms, molecules, ions).
Unimolecular Reaction
Reactions involving a single reactant entity to produce one or more products.
Usually happens when one reactant breaks up into two or more products.
A —-> Products
rate = k[A]
Biomolecular Reaction
Reaction involving two reactants to produce one or more products.
A + B —-> Products
rate = k[A][B]
2A ——-> Products
rate = k[A]^2
Termolecular Reaction
Reaction involving the simultaneous collision of three entities.
*Rare
2NO + O –> 2No,2
rate = k[NO]^2[O,2]
Rate Limiting Step (Role Determining Step)
Slowest step in an elementary reaction.
*Slowest step is the first used in a rate law. If slowest step is after fast step must solve differently.
Overall Reaction
Sum of all the elementary steps of the reaction.
Intermediate vs. Catalyst
Intermediate appears on the products side first then cancels out. Catalyst appears on the reactant side first then cancels out.
k,1 Elementary Reactions
The forward reaction
Enthalpy
The internal energy of a system plus the P*V
Arrenihus Equation (Def)
Describes the relationship between the reaction rate and temperature for chemical reactions.
