physical chemistry (Fabio) Flashcards
define molecularity
The molecularity of an elementary reaction is the number of molecules involved in the collision.
what is a unimolecular reaction and give an example
unimolecular reaction, a single molecule is involved
– e.g., radioactive decay, cis-trans isomerisations
what is a bimolecular reaction
bimolecular reaction, the all-important collision
involves two distinct molecules colliding.
These molecules might be of identical
chemical composition or different.
what value can molecularity not be
- can not be zero, fractional, infinite or imaginary
- can not be greater than three because there is not enough space
what is the rate equation for a first order reaction in respect to A
v=k[A]
what is the rate equation for a first order reaction in A and a first order reaction in B
v=k[A][B]
what is the rate equation for a second order reaction with respect to A
v=k[A]^2
for a zero order reaction what is the rate of reaction
the rates of zero order reactions do not vary with increasing or decreasing reactant concentrations. this means the reaction rate is equal to the rate constant k of that reaction
what are the units for a zero order reaction
Ms-1
for a first order reaction what is the rate of reaction
the rate of reaction increases linearly with increasing concentration of reactant
what are the units for a first order reaction
s-1
for a second order reaction what is the rate of reaction
normally dependent on temperature and relative concentration
what are the units for a second order reaction
M-1s-1
what is the half life equation for a zero order reaction and what does it depend on
t1/2 = [A]0/2k
depends on initial conc
what is the half life equation for a first order reaction and what does it depend on
t1/2 = 0.693/k
the half life is independent on the inital concentration
what is the half life equation for a second order reaction and what does it depend on
t1/2 = 1/k[A]0
half life depends on the inverse of inital conc
what is the arrhenius equation
k=Ae^-Ea/RT
k the observed rate constant
A is the pre exponential factor
Ea is activation energy
R is the universal contant
T absolute temperature
what is the equation for the rate of a chemical equation
rate of chemical reaction = number of collisons per secondfraction of collisions with proper orientationfraction of collisions with sufficient energy
What is the pre exponential factor A
number of collisions per second*fraction of collisions with proper orientation
what is the equation when comparing rates of reaction measured at any two temperatures
lnK1/K2=Ea/R(1/T2-1/T1)
what is transition state theory
It is based on the idea that a molecular collision that leads to reaction must pass through an intermediate state known as the transition state
what is the rate of reaction of transition state theory
rate = transition state concentration*decomposition frequency
what can transition state concetration be written as
e^-deltaG/RT
what can decomposition frequency be written as
v = KbT/h
what is Michaelis-menten rate law
The Michaelis-Menten rate law describes the rate of enzymatic reactions. Enzymes are biological catalysts that accelerate chemical reactions in living organisms. The Michaelis-Menten rate law specifically describes the rate of an enzymatic reaction involving a substrate (S) binding to an enzyme (E) to form an enzyme-substrate complex (ES), which then converts to the product (P) and releases the enzyme
what is the equation for the Michaelis - menten rate law
v=Vmax[S]/Km+[S]
V is the reaction rate or velocity.
Vmax is the maximum reaction rate, which occurs when the enzyme is fully saturated with substrate.
[S]is the concentration of the substrate.
Km is the Michaelis constant, which is a measure of the affinity of the enzyme for its substrate. It represents the substrate concentration at which the reaction rate is half of Vmax
what does the michaelis-menten equation show
The Michaelis-Menten equation shows that the reaction rate increases as the substrate concentration increases. However, at high substrate concentrations, the rate approaches Vmaxindicating that the enzyme is saturated with substrate.
what is a chain reaction
some reactions involve multiple intermediates which are produced and consumes through several steps, these are called chain reactions and the intermeidates are known as chain carriers.
what is a consecutive reaction
reactions where the reactant forms an intermediate species which subsequently reacts to form the product, catalysts generally react with one or more reactants to form intermediated that subsequently give the final reaction product in the process regenerating the catalyst
