Kinetics Lesson 4-6 MIDTERMS

• Parallel Reactions

• Series Reactions

• Independent Reactions

Three Basic Types of Multiple Reactions

Competing reactions

Parallel reactions are also called _____________

Parallel reactions

The reactant is consumed by two different reaction pathways to form different products

desired and undesired

In Parallel reactions, the reactant is consumed by two different reaction pathways to form different products: _________ and _________

To maximize formation of the desired product

The goal of engineers in parallel reactions

Consecutive Reactions

Series reactions are also called?

Series Reactions

The reactant forms an intermediate product, which reacts further to form another product.

Independent Reactions

Reactions occurring simultaneously but independent from each other. Occur in feed stocks containing many reactants.

Cracking of crude oil to form gasoline

Example of Independent Reactions

Autocatalytic Reactions

A reaction in which one of the products of reaction acts as a catalyst.

A catalyst

-substance that affects the rate of reaction but emerges from process uncharged.

molecular path (mechanism)

A catalyst usually changes a reaction rate by promoting a different __________________ for the reaction.

FALSE
A catalyst can accelerate the reaction rate but cannot change the equilibrium.

TRUE or FALSE
A catalyst can accelerate the reaction rate but CAN change the equilibrium.

• Gaseous reactants

• Gas-phase reaction

• Volume changes with time

Properties of a reaction in a constant pressure batch reactor

The volume of the reacting system varies linearly with conversion

What is the assumption in Autocatalytic Reactions?

Half-life

time it takes to convert for half of the initial concentration.

Space time,

time required to process one reactor volume of feed measured at specified condition.

Fao

time required to process one reactor volume. It is the time it takes for the amount of fluid that takes up the entire volume of the reactor to either completely enter or completely exit the reactor.

Fao

also used as capacity measurement for chemical reactors.

Space Velocity, s

the volume of entering feed at specified conditions per unit time per void volume of reactor.

Holding Time

- retention time of reactants inside the reactor volume.

1/t

The unit of k for a first order elementary reaction is

Directly proportional

Relationship of K to how far the reaction is to completion

2

If the temperature of a chemical reaction is raised by I0°C, the rate of reaction is increased by a factor of about

Adding a catalyst

The activation energy, E of a reaction may be lowered by

Rate equation

The mechanism of a reaction can sometimes be deduced from

Mass action

The law governing the kinetics of a reaction is the law of

does not depend on the initial concentration

The equilibrium constant in a reversible chemical reaction at a given temperature

Rate of reaction

It increases the number of particles with the necessary activation energy

Zero order

If the rate of reaction is independent of the concentration of the reactants, the reaction is said to be

Temperature

The specific rate of reaction is primarily dependent on.

molecularity of the reaction

The rate of reaction is not influenced by

Non-elementary

For the reaction 2A(g) + 3B(gl ~ D(g) + 2E(g) with r0 = kCAC8 2 the rea~tion is said to be

Pressure

Chemical reaction rates in solution do not depend to any extent upon

3

The overall order of reaction for the elementary reaction A+ 2B = Cis

2ra

The rate of formation of B in terms ofrA (where rA = -kCACb&2 )

is

0

The net rate of reaction of an intermediate is