Week 1 - kinetics and equilibrium

Collision theory

In order to react molecules, they must collide

Reaction rate and concentration of reactants relationship

As concentration of reactants increases, reaction rate increases (directly proportional)

Reaction rate and temperature relationship

As temperature increases, reaction rate increases (directly proportional)

Instantaneous reaction rate

Rate at a given point in time/one specific concentration, slope of the tangent

(steeper —> greater concentration, less steep → less concentration)

Unique average reaction rate

-1/a(ΔA/Δt) = -1/b(ΔB/Δt) = 1/c(ΔC/Δt) = 1/d(ΔD/Δt)

Average reaction rate

Change in concentration of a product or reactant over time

ΔA/Δt

ΔA = concentration of A (mol/L)

What is a rate law? What is the equation for a rate law?

an equation that relates the speed of a reaction to the concentration of its reactions

ex) aA + bB —> cC + dD

k[A]^x[B]^y (relates to concentration of the reactants)

• k → constant

• x, y → reaction order

• A, B → reactant

When should we use the stoichometry of the entire equation to write the rate law?

only when the reaction is an elementary reaction (i.e., it happens in a single step, NOT multiple steps)

ex) aA + bB → dD (only one step)

What is the best way to determine the rate law?

method of initial rates

Why is using the stoichometry of the entire equation generally inaccurate?

Because most reactions happen in multiple steps, not a single step

Which factors impact reaction rate?

1. temp

2. concentration of reactant

3. orientation of reactants

Our rate law is generally dependent on our ___ step(s) of the reaction.

Our rate law is generally dependent on our slow steps of the reaction because it acts as a traffic jam, where the reaction cannot go faster than its slowest step.

What is an intermediate?

Smth that is formed during a reaction and not present in the final reaction (used up in the reaction)

ex) A multi-step reaction is A+B+D → E

Step 1: A+B → C

Step 2: C+D → E

C is the intermediate because it is only formed during the reaction but not present in the final reaction

(It is NOT a reactant or a product)