Chemistry Chapter 16 - Kinetics

Kinetics

the study of the rates of chemical reactions and the steps by which they occur

Kinetics answers two specific questions

Will the reaction react?

How fast will it react?

Just because a reaction is thermodynamically favorable does not mean…

it will proceed automatically

Some reactions need…, others proceed…

a push to get started; on their own

Some reactions proceed at an extremely…; others are…

slow rate; rapid

Thermodynamics is…

path-independent; relates only to the starting and ending points of the reaction

Kinetics is…

path-dependent; it is more concerned with how the reaction proceeds from point A to B

Energy Diagrams

graph the energy changes during a reaction

The highest point on an energy graph represents…

the energy needed by the reactants to form the products

Collision Theory

Particles must collide; the particles must collide in the proper orientation necessary for the rearrangement of atoms and electrons; the collision must be energetic enough to form products

Effective Collisions

those that are sufficiently energetic and properly oriented

How is the rate of reaction increased?

any factor that increases the number of effective collisions

Activation Energy (E_a)

the minimum energy necessary for a chemical reaction to occur

Each reaction has a…

specific activation energy that must be overcome in order for the reaction to occur

…prevents the occurrence of many reactions that are spontaneous

activation energy

The…the activation energy is, the faster the reaction will occur

lower

Energy released during…can provide the activation energy for more collisions

bond formation

Reaction Steps

the breaking of bonds and the formation of new bonds takes place at the same instant

Activated Complex

an unstable, intermediate substance that forms as the reactants transition into the products

Rate Law

an equation that mathematically describes how fast a reaction occurs

Rate Formula

concentration of reactants/time

Sometimes, concentration will…a graph, sometimes…

not impact; it will

Writing a Rate Law

Rate = k[A]ⁿ[B]^m

n and m are the rate orders

[A] and [B] are the concentrations of the reactants

Zero Order

the concentration does not affect the rate; n = 0

First Order

the concentration affects the rate directly; n = 1

Second Order

the concentration will change at a rate of the power of 2; n = 2

Thermodynamics asks the question…

Can it react?