Unit 2: Reaction Equilibrium

Question 0

In a reaction that is said to be “reversible” while the forward reaction proceeds so does….

Answer 0

The reverse reaction

Question 1

In a closed system most reactions are _____.

Answer 1

Reversible

Question 2

At equilibrium the forward reaction rate is always equal to the…

Answer 2

Reverse reaction rate

Question 3

Only _____ reactions form an equilibrium

Answer 3

Reversible

Question 4

For a reaction to be reversible a ___ ____ is needed

Answer 4

Closed system

Question 5

At equilibrium no _____ changes occur

Answer 5

Macroscopic

Question 6

At equilibrium the _____ of both the reactants and products are constant (but not necessarily equal).

Answer 6

Concentration

Question 7

A dynamic equilibrium if upset will…

Answer 7

Re-establish itself

Question 8

A state of equilibrium exists whenever… (4 things)

Answer 8

1. There is a closed system
2. The reaction is reversible
3. There is no change in macroscopic properties
4. The temperature is constant

Question 9

Give 3 properties you could monitor so see if a equilibrium exists

Answer 9

• change in pressure
• change in concentration
• change in colour

Question 10

The two driving factors for all chemical processes are…

Answer 10

• enthalpy

- entropy

Question 11

Entropy is…

Answer 11

The tendency to achieve a higher state of disorder/randomness

Question 12

Enthalpy is…

Answer 12

The tendency to achieve a lower heat content

Question 13

All reactions want a ____ enthalpy and a ____ entropy

Answer 13

Lower

Higher

Question 14

Rank the following states by which is most favoured by entropy to least favoured by entropy. (Include > symbols)

Solid, liquid, aqueous, and gas

Answer 14

Gas»aqueous>liquid» solid

Note that aqueous has more entropy than liquids but it is not as great of a difference between liquids and solids

Question 15

When both entropy and enthalpy favour the formation of products a _____ does not exist

Answer 15

Equilibrium

Question 16

When both entropy and enthalpy favours the reactants the ____ does not go to _____

Answer 16

Reaction

Completion

Question 17

What 4 factors can shift the equilibrium

Answer 17

• concentration
• pressure
• temperature
• volume

Question 18

According to Le Chatelier’s principle whenever a stress is added is applied to a system the system will ____ so as to ____ the stress and re-establish ____.

Answer 18

Shift
Reduce
Equilibrium

Question 19

An increase in concentration increases the ____ ____ which in turn increases the ____ ____.

Answer 19

Collision frequency

Reaction rate

Question 20

Equilibrium favours a shift ____ from the increased concentration.

Answer 20

Away

Question 21

A decrease in volume of the closed system means there is a _____ ____ of the system which ____ the ____ ____ which leads to the ____ ____ increasing

Answer 21

Increased pressure
Increases
Collision frequency
Reaction rate

Question 22

Equilibrium favours a shift ____ from the greater number of gas molecules to the _____ number of gas molecules

Answer 22

Away

Lower

Question 23

An increase of the pressure of a container is a ____ in the volume of the container which leads to an ____ of the collision frequency and reaction rate

Answer 23

Decrease

Increase

Question 24

Pressure can be increased by adding a ____ gas and this added gas will have ____ affect on the equilibrium

Answer 24

Noble | No

Question 25

When a noble gas is added the overall ____ of each species of gas in the equilibrium will ____

Answer 25

Pressure | Increase

Question 26

An _____ in temperature increases both the forward and reverse reaction rates

Answer 26

Increase

Question 27

When the reaction is endothermic and heat is added the equilibrium shifts toward the ___ side

Answer 27

Product

Question 28

When the reaction is ______ and heat is added the equilibrium shifts toward the reactant side

Answer 28

Exothermic

Question 29

What effect do catalysts have on equilibrium

Answer 29

Catalysts have no effect on equilibrium | Catalysts increase both the forward and reverse reaction rate equally and equilibrium is reached faster

Question 30

[products]/[reactants] is the ____ expression

Answer 30

Keq

Question 31

When using the Keq expression make sure that the power (which are the coefficients of the products and reactants) are always in the ____ whole number ration

Answer 31

Lowest

Question 32

If you reverse the chemical equation then the equilibrium expression will be the _____ of the original constant

Answer 32

Reciprocal

Question 33

When Keq is large the _____are favoured

Answer 33

Products

Question 34

Keq is small when the ____ are favoured

Answer 34

Reactants

Question 35

In a closed system nothing can....

Answer 35

Leave or enter

Question 36

Temperature ____ (can/cannot) effect the equilibrium

Answer 36

Can

Question 37

At a new temperature _____ (the same/a new) equilibrium is attained

Answer 37

A new

Question 38

Is the equilibrium different if the reaction started with and excess of products?

Answer 38

No | Same goes for excess of reactants

Question 39

In a ____ equilibrium no macroscopic changes occur

Answer 39

Dynamic

Question 40

When a dynamic equilibrium exists all observable qualities are constant but at the molecular level there is....

Answer 40

Constant back and forth reaction between reactants and products (which is a perfect balance)

Question 41

The rate of consumption of reactants is equal to the rate of....

Answer 41

Production of reactants

Question 42

Is [reactants] always equal to [products]?

Answer 42

No. The [reactants] differs from [products] in general but they can be equal

Question 43

Are the [reactants] and [products] constant at equilibrium?

Answer 43

Yes

Question 44

A system that is capable of equilibrium that is not at equilibrium will tend to...

Answer 44

Move toward a position of equilibrium

Question 45

A _____ change is a change which occurs by itself, without outside assistance

Answer 45

Spontaneous

Question 46

A reaction is expected to move spontaneously to the side of the reaction having minimum energy if.....

Answer 46

The energy barrier is low enough

Question 47

Endothermic reactions are not expected to occur ___ without if sufficient heat is not available

Answer 47

Spontaneously

Question 48

The side of the reaction having minimum _____ (entropy/enthalpy) is said to be favoured because molecules will tend to go to or remain at minimum energy

Answer 48

Enthalpy

Question 49

Do all Exothermic reactions go to completion?

Answer 49

No. Sometime the reverse reaction occurs to some extent so the reaction is then at equilibrium

Question 50

Can an endothermic reaction occur spontaneously? If so give an example

Answer 50

Yes. Chemical cold packs.

Question 51

Why is a highly random state favoured over a highly ordered state?

Answer 51

Because there are more random states possible

Question 52

What is entropy?

Answer 52

The amount of randomness in a system

Question 53

The greater the difference in the amount of randomness of products vs reactants the greater the ____ drive of the system

Answer 53

Entropy

Question 54

Minimum ____ favours the side of the reaction containing the "heat" term

Answer 54

Enthalpy

Question 55

If there is only a single phase in the entire reaction entropy favours the side with....

Answer 55

The most molecules

Question 56

Le Chatelier's Principle is...

Answer 56

If a closed system at equilibrium is subjected to a change, processes will occur that tend to counteract that change

Question 57

Solids and pure liquids are not included in the equilibrium expression because...

Answer 57

They have a constant concentration

Question 58

What is the only change that can affect the value of keq

Answer 58

Temperature change