Unit 1-Test 1-Kinetics and Equilibrium

Question 1

What is the Kinetic Molecular Theory?
What is KMT supported by?
(Pg 469 in Text)

Answer 1

-It is a theory that states that matter is made of particles(atoms,ions,or molecules) in continuous or constant motion.
An increase in temperature:
- increases the speed of particles
-reduces the forces of attraction between particles (According to Text: A theory that explains the ideal gas behavior based on the basis of random motion of gas particles)

KMT is supported by…

Diffusion: particles of a gas spread to fill their container (“perfume in a room”)

Pressure: a balloon remains inflated because gas particles are continuously hitting the sides of the balloon

Question 2

What is the Collision Theory? (Pg470)

Answer 2

• The theory that states reactant particles must collide with one another for a chemical reaction to occur.
• Particles must collide with proper orientation
• collisions must have enough intensity to break old bonds and allow new bonds to form.

Question 3

Kinetic Energy

Answer 3

is the energy of motion, ex

Question 4

Potential Energy

Answer 4

energy that is stored ex

Question 5

Activation Energy(Ea)

Answer 5

the minimum energy that is required for a successful reaction between colliding molecules

Question 6

Activated Complex

Answer 6

A highly unstable transition species that has partial bonds and is neither product nor reactant.
-It is a temporary,unstable, intermediate species that quickly decomposes to products.

Question 7

Enthalpy/Delta H

Answer 7

Enthalpy change(Delta H)- is the difference between the potential energy (PE) of the reactants and the potential energy (PE) of the products.

Question 8

Catalyst

Answer 8

A substance that increases the rate of a chemical reaction without being consumed by the reaction

Question 9

Reaction Mechanism

Answer 9

a series of steps that make up an overall reaction

Question 10

Enthalpy of reaction

Answer 10

the enthalpy change of a chemmical reaction. Delta H represents the heat of reaction or the enthalpy of reaction

Question 11

Elementary process

Answer 11

?

Question 12

Elementary reaction

Answer 12

• Each step in a reaction mechanism
• It is a reaction that involves a single molecular event ,such as a simple collision between atoms,molecules,or ions ;can involve the formation of different molecules,or ions;may involve a change in the energy of the starting molecules; cannot be broken down into simpler steps

Question 13

Reaction intermediates

Answer 13

Molecules, atoms,or ions that are formed in an elementary reaction/step,and consumed in a later elementary reaction/ step, but are NOT included in the overall reaction.

Question 14

Rate determining step

Answer 14

the slowest reaction step; determines the rate of the reaction.

Question 15

Endothermic

Answer 15

absorb more energy than they release ( ex photosynthesis)
The Delta H of a endothermic reaction is always positive. On a PE diagram the products are higher than the reactants.
Endothermic Equation=
AB+C –> AC +B

Question 16

Exothermic

Answer 16

-release more energy than they absorb(ex. burning)
The Delta H of an exothermic reaction is negative
-The reactants are higher than the products
Exothermic equation=
C+D + CD

Question 17

PE diagrams

Answer 17

diagrams that show changes in potential energy( stored chemical energy) during a chemical reaction

Question 18

Reaction Kinetics

Answer 18

is the study of the rate of a chemical reaction

Question 19

What is reaction rate & its formula?

Answer 19

Reaction rate (Quantitative)  measures how fast products are formed or how fast reactants are consumer. All reactions are bond breaking/bond forming events ,and the rate of a reaction depends on how quickly bonds are broken and how rapidly new bonds form.
Note: KMT and the collision theory are used to explain reaction rate.

         Change in Quantity           Rate = ------------------------------
        Change in time

Th units depend on what you’re measuring

Question 20

What are 6 methods for measuring reaction rate?

Answer 20

1. If there is an acid or base in the equation, monitor pH
2. Record changes in gas volume if there is a gas
3. If there is a gas in the equation, you can record changes in pressure
4. If solids are present, record changes in mass
5. Monitor absorption of light if there is colour change
6. Changes in electrical conductivity indicate changes in ion concentration

Question 21

With reference to the Collision theory, explain how concentration affects reaction rate

Answer 21

An increase in the concentration of a reactant usually increase the rate of a chemical reaction, this is because when the concentration increases..

• there are more particles
• which means more collisions between particles
• thus more successful collisions

Question 22

With reference to the collisions theory, explain how temperature affects reaction rate

Answer 22

An increase in temperature increase the rate of a reaction
This is because a higher temperature results in
-more collisions between particles
-more intense collisions
-more successful collisions,faster reaction rate.
AN INCREASE IN TEMP BY 10C WILL USUALLY CAUSE THE REACTION RATE TO DOUBLE

Question 23

explain how the nature of reactions affects the reaction rate

Answer 23

Compounds with fewer bonds to break will react more rapidly than compounds with many bonds

(ex. propane,C3H8, burns faster than candle wax , C25H52,because it has fewer bonds
- compounds with weak bonds react more rapid;y than compounds with strong bonds
- ions will react more rapidly than atoms and molecules

Question 24

With reference to the collision theory, explain how surface area affects reaction rate

Answer 24

Crushing a solid to produce a powder,or changing a substance to the gas phase,EXPOSES MORE PARTICLES FOR COLLISION
if more particles are available for collision there will be:-more collisions-more successful collisions,and a faster rate.

Question 25

With reference to the collision theory, explain how Catalysts affects reaction rate

Answer 25

a catalyst increases rate by providing a different reaction pathway or mechanism with a lower activation energy
- a catalyst IS NOT consumed by a chemical reaction

Question 26

What is the heat of reaction?

Answer 26

It is the same had Delta H or enthalpy.In other words it

is the difference between the PE of the reactions, & the PE of products.

Question 27

What is the formula for calculating Delta H, Ea rev,or Ea fwd

Answer 27

Ea fwd-Ea rev= delta H