Ch. 6 Kinetics Flashcards
Reaction rate units are
M/sec
mol/L x sec
What is the rate law?
an expression for the relationship between reactant concentrations and the rate of a reaction
What is the basic equation for rate law?
rate = K [A]^Y x [B]^z k = rate constant Y = order of reaction for A z = order of reaction for B
WHat is an order?
The degree to which the rate of the reaction is dependent on each reactant.
Order of reactant = coefficient
How would you calculate the overall order of a reaction?
Sum of the reactants orders (Y+Z = sum)
In a multistep rxn, the rate of reaction is dictated by?
The slowest step (rate-limiting step)
When determining an initial rate method, how do you use the trials?
You determine in which two trials is reaction A is different but reaction B remains the same. The same is done for reaction B.
The Arrhenius equation defines k, the rate constant, what is it?
k = rate of a reaction k = Ae^-Ea/RT
A - frequency of collisions between reactants
Ea -activation energy
R- Ideal gas constant
T - temp (in kelvin)
This rate constant can only be effected by activation energy and the temp.
(Ea/RT - decrease = rate constant increases)
(larger values of Ea = Ea/RT negative = lower reaction rate)
(there is an inverse relationship between reaction rate and activation energy)
A fundamental concept is that lower activation energy has what effect on reaction rate?
Lower activation energy = higher reaction rate
The temperature has what relation with reaction rate?
How does this relate to the Arrhenius equation?
Direct relationship
High temp = smaller Ea/RT = increased rate reaction)
What are the two main ways to increase reaction rate?
reduced activation energy and increased temperature
gas reactions can be affected by pressure, higher pressure = increased rate
What is activation energy?
The energy needed to reach the transition state
How do catalyst work?
They reduce the activation energy needed, thereby increasing the reaction rate.
What is a zero-order reaction?
the exponents add to zero.
In this situation the enzyme is saturated, the concentration of reactant outnumber the active site for the enzyme.
Catalyst/enzyme become rate-limiting
