Chapter 13 Flashcards
What four things affect the rate of a reaction?
Concentration, Temperature, Surface area, Catalysts
From the equation 2 NO2»_space;> 2 NO + O2, the expression (ΔNO2) / (Δt) represents what? Why will it be negative?
The rate at which the concentration of NO2 changes. It will be negative because it denotes the disappearance of a reactant. The same equation for NO or O2 will be positive.
The general rate law for aA + bB»_space;> cC + dD is
-1/a x ΔA/Δt = -1/b x ΔB/Δt = 1/c x ΔC/Δt = 1/d x ΔD/Δt
What is used to measure pressure change? Concentration change?
A manometer. Spectroscopy.
EQUATION Rate
k x [A]^m x [B]^n, where k is a reaction specific constant, A and B are the equation’s reactants, and m and n are their respective orders.
How do you find the order of a reactant?
Do two experiments where only that reactant changes, and solve for the following.
(factor that the reactant increased by)^order = ratio that the product increased by
The units of k are
M^(1-general order) x s^-1
EQUATION integrated rate law, first order
ln[A]_t = -kt + ln[A]_initial
EQUATION half life, first order
ln 2 / k (or 0.693 / k)
Collision theory states that the rate of reaction depends on the ______, the ______, and the _______.
number of collisions, correct orientations of the particles, energy of the particles
In transition state theory, molecules must overcome an _____________ to reach a ________, where the molecules are not fully _____________.
activation energy barrier, transition state, bonded to one another
EQUATION Effect of Temperature on reaction rates
k = (A)(e^(-E_a / (R)(T)))
What’s a reaction mechanism?
A step-by-step sequence of elementary reactions.
In an elementary reaction, the order of a substance equals
its stoichiometric coefficient.
The ____ elementary reaction in a mechanism is the rate-determining step.
slowest
Catalysts make themselves ______, E_a ______, k _____, and the reaction _____.
unchanged, lower, higher, faster
Homogenous catalysts are
in the same phase as the reacting system.
Heterogeneous catalysts are usually _____ in a reacting system whose phase is ___________.
solid, liquid or gas
The four steps of heterogeneous catalysis are
(1) Adsorption
(2) Diffusion
(3) Reaction
(4) Desorption (break away from molecule)
