Reaction Kinetics

Chem 12 - Mr. Chan "I love my wife x3"

Reaction rate

Change in moles / time

The reaction rate is dependent on the …

Mole ratio

Reactions between ions are generally … because of the … between them

Fast; simple attraction

Reactions between molecules are generally … because … before the reaction can occur

Slower; bonds must break

Rank the following phases from slow to fast: gas, solid, liquid and ion

Solid, liquid, gas, ion

Homogenous reactions is where …

Reactants are in the same phase

Heterogenous reactions is where …

Reactants are in different phases

For a reaction to happen, particles must … with sufficient … and correct …

Collide; energy; geometry

Threshold energy is …

The minimum kinetic energy

Overall, the rate of a reaction is dependent upon the number of …

effective collision

Label this Boltzmann Distribution

Factors that affect rate are:

1. Temperature

2. Concentration

3. Catalyst & Inhibitor

4. Nature of Reactants

5. Surface Area

Increase in concentration … rate of reaction because …

increase, more particles colliding.

How does the Boltzmann Distribution change or not change with an increase in concentration?

Average energy and threshold stays same, while graphs becomes taller.

Increase in surface area … rate of reaction because …

increase; more exposed area for collisions.

Does the distribution curve change with a change in surface area? Why?

No because the energy of the particles have not changed.

A change in surface area only affects … reactions

heterogenous

Increasing temperature … rate of reaction because the particles … and …

increase; have more energy; collide more

A temperature increase is different from concentration, the … of effective collisions increase, while the number of molecules …

fraction; stay same

A 10 degree C increase in temperature will double the reaction rate for a … reaction because the increase in the …

slow; fraction of effective collisions will be greater.

With increasing temperature, how does the distribution change?

average energy shift right and down

A catalyst … a reaction without being …

speeds up a reaction, being used

A catalyst does what to the distribution? Does it increase the fraction of effective collision?

Lowers threshold energy ; Yes

Nature of reactants because some substances are …

more reactive than others.

A fast reactant has … threshold energy, while a slow has …

low; high

Label this potential energy diagram

activated complex is the point where reactants form a …, and where bonds are …

high energy intermediate compound; broken and formed.

Activation energy (forward) is read …, which is needed to form … forming …, and calculated by …

left to right; activated complex; products , PE(ac) - PE(react)

Activation energy (reverse) is read …, and is needed to form … forming …

right to left, activation complex, reactants.

Change in enthalpy is calculated by …, and positive means … and negatives means …

PE(product) - PE(react); endothermic, exothermic.

Exothermic reactions looks like:

React → product + energy

endothermic reactions looks like:

reaction + energy → product

particles collide, KE … and PE …, but total …

decrease, increase; stays same.

An activated complex has the … PE and … KE

highest, lowest

Reaction mechanism is a … for a reaction to occur

series of steps

Two types of reaction mechanisms:

1. Elementary process

2. Ternary process

In elementary process, a reaction occurs in … and has … activated complex and … activation energy

one step; one; one

In ternary process, a reaction occurs in … and has … step with the … activation energy

series of collisions; slow; highest.

PE diagrams of ternary process have at least …, and each corresponds with an …

two activated complexes; activated complex

other steps in a ternary process are considered …

fast

Change in the slow step has the … effect on the rate of reaction

greatest

Ea(slow) is considered the Ea of the … reaction

overall

Between the activation energies is a valley where … are found

reaction intermediates

reaction intermediates are produced … and used …

in an early step; in a later step

Catalysts a are used in … and produced …, and is used …

an early step; a later step; once

Are react intermediates and catalysts written in an overall equation?

no

What is different between an reaction intermediate and activated complex

R.I. are produced and used, while A.C. forms briefly for old bonds to break and new bonds form.