lecture 8 - chemical kenetics Flashcards
What does A represent in the Arrhenius equation?
The frequency factor, related to the likelihood of collisions with proper orientation.
How does k vary with temperature?
k increases as temperature rises, because molecules have more energy.
Define reaction order.
The exponent to which the concentration of a reactant is raised in the rate law
What is the overall reaction order?
The sum of the exponents in the rate law.
Describe zero-order reactions.
Rate is independent of reactant concentration.
Describe first-order reactions.
Rate is proportional to reactant concentration.
Describe second-order reactions.
Rate is proportional to the square of reactant concentration.
What is the half-life formula for a first-order reaction?
t (1/2) = In (2)/k
How does half-life depend on concentration in first-order reactions?
A: It is constant and independent of concentration.
What is the half-life formula for a second-order reaction?
t(1/2)=1/K[A]0
How does half-life depend on concentration in second-order reactions?
It decreases as the initial concentration increases.
Why is the rate constant k independent of concentration?
Because k depends only on temperature and activation energy.
Q: How does a catalyst affect the reaction coordinate diagram?
A: Lowers the activation energy peak, making the reaction faster.
What is the role of temperature in the Arrhenius equation?
A: Higher temperature increases k , leading to faster reactions.
Q: How do you identify the order of a reaction experimentally?
A: Measure how the rate changes with reactant concentration.
Why are products not included in the rate law?
A: The rate law is based only on reactant concentrations and their effect on the rate.
