Chem 2 exam 4

What is transition state

The high-energy, unstable species formed during the reaction

What factors affect reaction rate (collision theory)

Physical form: surface area, state

Concentration/pressure

Temperature

Catalyst

According to collision theory, a chemical reaction occurs only when reactant molecules:

Collide with sufficient energy and proper orientation

How does temperature affect the reaction rate in collision theory

A greater fraction of collisions have sufficient energy to bond

The number of collisions increases

What does activation energy (Ea) represent

The minimum energy required to form the transition state

compares the energy of reactants to transition state

What happens if a reaction has a very large activation energy?

proper orientation is difficult to achieve

Using collision theory: How does a catalyst make a reaction faster?

A catalyst coordinates collisions to guarantee proper orientation.

A catalyst coordinates the movements of reactant molecules so that collisions occur at the proper orientation every time. The bonding process does not rely on random collisions.

Using transition state theory: how does a catalyst make a reaction faster

A catalyst lowers the required Energy of Activation (Ea) for the formation of the transition state

When using a catalyst, is more or less energy needed to form bonds?

Less energy. Due to the coordination of the collisions to have greater efficiency, less energy is needed in order to get bonds to form.

requirements of Positron/EC decay mode

An element that is too light (mass number lighter than periodic mass number)

Neutron to proton ratio is too low

What nuclei is more likely to undergo Beta decay

Things that are too heavy (higher mass number than on periodic table)

What form of decay happens when neutron to proton ratio is too high?

Beta decay

Gamma ray

More penetrating than a beta ray or alpha ray

consists of photons, not neutrons

It is not deflected by an electric field

Catalyst

Consumed in one step of the reaction, regenerated in a later step

Not present in the overall balanced equation

Appears on the reactant side first and reappears on the product side later

Substance added to the reaction to coordinate collisions

U-235

Isotope of uranium capable of fission

Enriched uranium fuel for nuclear reactors

What is a significant difficulty in using fusion as an energy source?

The extreme conditions required to initiate and sustain fusion reactions

What type of nuclear process requires extremely high temperatures to occur?

Fusion

Fusion

Small nuclei combine into a larger nucleus

Requires extreme heat to initiate

Basis of hydrogen bomb

Powers the sun and stars

2H combines with 3H to 4He and a neutron and LOTS OF ENERGYY

Critical mass

The smallest amount of fissionable material required to sustain a nuclear chain reaction

Fission

Larger nuclei split into smaller nuclei

Bombards nuclei with neutrons

control rods- used to absorb neutrons to control rate of nuclear reaction

Alpha particle

4/2 He (helium nucleus)

decay mode that results in an increased atomic number for the decaying atom

Beta

-1

How does increasing reactant concentration effect collision theory?

Causes collisions to occur more frequently

order of importance of collision theory

1. Collisions(more is better)

2. Of proper orientation

3. With enough energy to make and break bonds

10 degree celsius rule

Every 10 degrees doubles the rate

How does increasing surface area increase reaction rate

Exposes more particles to collide= more collisions

How does increasing temperature increase reaction rate

Particles have more energy= move faster= collide more frequently and with more force

How does the addition of a catalyst increase reaction rate

Coordinates the movements of reactants to guarantee that collision occurs at the proper orientation

COLLISIONS NO LONGER RANDOM

Advantages of nuclear power

An enormous amount of energy for a long time

Generates low greenhouse gas emissions

Disadvantages of nuclear power

Radioactive waste is difficult and expensive to be stored safely

Risk of emergencies or accidents that can release radiation into the environment

Transition state

High energy, temporary, unstable stage in the process of converting reactants into products

Control rods

Used to absorb excess neutrons and slow fission to a manageable rate

Breeder reactor

Reactor that makes more fissionable material than it consumes

What isotope of uranium is required for fission?

235

The longer the half life, the more _____ the isotope

stable

Which radiation particle is the most dangerous?

Gamma

A mechanism shows how many particles of each substance is needed to construct

the transition state. This shows up in its rate law equation as

exponents

Nuclear fission is based upon emission and absorption of which radiation type?

Neutrons

Which radiation particle is associated with radon in houses?

Alpha

Isotope 3/1H is called

Tritium