Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Chemistry > Chapter 10 - Reaction rates and Equilibrium > Flashcards

Chapter 10 - Reaction rates and Equilibrium Flashcards

You may prefer our related Brainscape-certified flashcards:
Periodic Table flashcards Chemistry 101 flashcards AP® Chemistry flashcards Organic Chemistry 101 flashcards
1
Q

Define Activation Energy

A

The minimum energy required to start a reaction by the breaking of bonds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What does rate of reaction measure (2)

A

How fast a reactant is being used up
or
how fast a product is being formed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What features can affect rate of reaction?

A

Concentration or pressure
Temperature
Use of a catalyst
Surface area of solid reactants

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What does the collision theory state?

A

That 2 reacting particles must collide for a reaction to occur.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are the 2 conditions reacting particles have to meet for a successful collision?

A

The particles have sufficient energy to overcome the activation energy barrier of the reaction
The particles collide with the correct orientation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the equation for rate of reaction?

A

Rate (moldm-3s-1) = change in concentration (moldm-3)/

Time (s)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What happens to rate of reaction when the concentration of a reactant is increased? Why?

A

The rate increases because the number of particles in the same volume increases and therefore particles are closer together and will collide more frequently. In a given time there will therefore be more effective collisions and the rate of reaction will increase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What happens to rate of reaction when the pressure of a reactant is increased? Why?

A

The rate increases because the same number of particles are compressed into a smaller volume and therefore particles are closer together and will collide more frequently. In a given time there will therefore be more effective collisions and the rate of reaction will increase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are the 2 methods for following the progress of a reactiopn?

A

Monitoring the removal of a reactant (decease in concentration)
Monitoring the formation of a product (increase in concentration)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is one method of determining rate of reaction for a reaction that produces gases?

How would you record this data?

A

Monitoring the volume of gas produced at regular intervals by collecting the gases formed.
Use a water trough and an upside down measuring cylinder filled with water, connected to a conical flask where the reaction is taking place by a delivery tube to measure the gas formed.
Time(x) against volume of gas produced (y)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is another method of determining rate of reaction for a reaction that produces gases?

How would you record this data?

A 
Monitor the mass loss of the reactant using a balance. 
Mass lost (y) against time (x)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is a catalyst and what does it do?

A

A catalyst is a substance that changes the rate of reaction without undergoing any permanent change itself

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How does a catalyst increase the rate of reaction?

A

It provides an alternative reaction pathway with a lower activation energy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are the types of catalysts?

A

Homogeneous

Heterogeneous

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is a homogeneous catalyst? What does it do?

A

A catalyst with the same physical state as the reactants. It reacts with the reactants to form an intermediate which then breaks down to give the products and regenerates the catalyst

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are homogeneous catalysts used for? (2) and in each case what is the catalyst

A

Making esters - sulfuric acid

Ozone depletion - Cl radicals

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is a heterogeneous catalyst and what does it do?

A

It is a catalyst that has a different physical state to the reactants. The reactant molecules are weakly bonded (adsorbed) onto the surface of the catalyst where a reaction occurs. The product molecules are then desorbed from the catalyst. The catalyst is usually a solid in contact with gaseous or aqueous reactants

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What are heterogeneous catalysts used for? (2) and in each case what is the catalyst

A

Making ammonia via the haber process - solid Iron

Hydrogenation of alkenes Ni(s)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What are the positives to the use of catalysts? (4)

A

Lower production costs as temperatures requirements are reduced
More products can be produced more quickly using less energy - increases profitability
It lowers the temperatures, reducing the demand for fossil fuels so less CO2 is emitted
Better atom economy (reduces wastage and pollutants

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What are the negatives to the use of catalysts? (4)

A

Some catalysts are toxic so need to be disposed of carefully
Catalysts can be very specific and only catalyse one reaction
Catalysts can be very expensive
Some catalysts are poisoned by impurities and will become inefficient over time

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What does the Maxwell Boltzmann distribution graph show?

A

The energy distribution of all molecules in a gaseous state

22
Q

Describe the basics of a Maxwell Boltzmann distribution graph

A

The number of molecules is on the Y axis
The energy is on the X axis
The activation energy is represented by a vertical line coming up from the energy

23
Q

Where does the curve start on a Maxwell Boltzmann distribution graph?

A

At the origin (0,0)

24
Q

What does the area under the Maxwell Boltzmann distribution graph give?

A

The total number of molecules

25
Q

What does the peak on the Maxwell Boltzmann distribution graph show?

A

The most likely energy of any molecule

26
Q

What happens if you use a catalyst in a reaction and how is this shown on a Maxwell Boltzmann distribution graph?

A

Provides an alternative energy pathway which lowers the activation energy which means more molecules have sufficient energy to react when they collide. This is represented as a vertical line from the X axis but is a smaller energy and is therefore closer to the y axis than the activation energy without a catalyst

27
Q

At a higher temperature what happens to the most likely energy of any molecule?

A

It will increase (meaning the peak will be further from the Y axis at a higher energy)

28
Q

What happens to the area of the Maxwell Boltzmann distribution graph when the temperature increases?

A

It remains the same because no new molecules have been introduced

29
Q

When at a higher temperature what happens to the number of molecules that have energy equal to or greater than the activation energy?

A

It increases because molecules have more energy

30
Q

What happens to the number of collisions at a higher temperature?

A

It increases in frequency because the molecules have more energy and will collide more often due to moving more

31
Q

What happens to the rate of reaction at higher temperatures?

A

It INCREASES due to an increase in energy of molecules and an increase in the frequency of collisions

32
Q

What conditions are required for dynamic equilibrium to be achieved?

A

Closed system with a reversible reaction

33
Q

Define closed system

A

A system where reactants and products are isolated from their surroundings so their temperature, pressure and concentrations remain unaffected by outside influences.

34
Q

Define dynamic equilibrium

A

exists in a closes system where the rate of the forwards reaction is equal to the rate of the reverse reaction and the concentrations of the products and reactants has not changed

35
Q

List 4 features of dynamic equilibrium

A

the concentrations of the products and reactants does not change
the rate of the forward reaction equals the rate of the backwards reaction
it is in a closed sytem
there is no change in macroscopic properties

36
Q

What 3 physical changes can be predicted by Le Chatelier’s principle?

A

Change in temperature
Change in pressure
Change in concentration

37
Q

What does Le Chatelier’s principle state?

A

when a system in equilibrium is subjected to an external change the system readjusts itself to minimise the effect of that change

38
Q

What happens to the position of equilibrium if the concentration of a product is increased?

A

The equilibrium will shift to the left to form more reactants

39
Q

What happens to the position of equilibrium if the concentration of a reactant is increased?

A

The equilibrium will shift to the right to form more products

40
Q

What happens to the equilibrium if pressure is increased?

A

Equilibrium shifts to the side with fewer molecules

41
Q

What happens to the position of equilibrium if pressure is decreased?

A

Equilibrium shifts to the side with more molecules

42
Q

What happens to the position of equilibrium if pressure is increased or decreased in a reaction which has the same number of molecules on both sides?

A

There will be no effect on the position of equilibrium because there are the same number of molecules on either side

43
Q

What happens to the position of equilibrium if temperature is decreased in a exothermic reaction?

A

It shift to the exothermic side which is the product side

44
Q

What happens to the position of equilibrium if temperature is increased in an exothermic reaction?

A

It shift to the endothermic side which is the reactant side

45
Q

What happens if the position of equilibrium if temperature is increased in an endothermic reaction?

A

It shift to the endothermic side which is the product side

46
Q

What happens to the position of equilibrium if temperature is decreased in an endothermic reaction?

A

It shift to the side exothermic side which is the reactant side

47
Q

Do catalysts affect the position of equilibrium?

A

No but it increases the rate of the forwards and reverse reaction equally.

48
Q

How can the position of equilibrium be calculated?

A

Using the equilibrium law where you use the concentrations of products and reactants at equilibrium

49
Q

If the value of equilibrium constant is 1 what does it mean about the position of equilibrium?

A

It is halfway between the products and reactants

50
Q

If the value of equilibrium constant is less than 1 what does it mean about the position of equilibrium?

A

It is towards the reactant side

51
Q

If the value of equilibrium constant is more than 1 what does it mean about the position of equilibrium?

A

It is towards the product side

52
Q

What is an equilibrium constant?

A

The actual position of equilibrium

Chemistry (21 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions