Brainscape's Knowledge GenomeTM

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


See full index

Chapter 10=> Reaction Rates And Equillbrium > 10.1 - 10.4 > Flashcards

10.1 - 10.4 Flashcards

1
Q

Complete the sentence:
For a collision to occur….

A
  • particles must COLLIDE
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Define the term rate of reaction

A
  • the change of concentration/amount of a reactant or product per unit time
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

How do you work out the rate

A

amount of reactant used/ product made
______________________________________________
Time

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

What is collision theory

A
  • The theory that for a reaction to occur particles have to:
    1) collide in the right DIRECTION/ORIENTATION
    2) have the minimum amount of KINETIC ENERGY
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Define the term activation energy

A
  • the minimum amount of energy required for a reaction to occur
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

At the peak of the energy profile diagram what does the peak show

A
  • that bonds have sufficient amount of energy to break
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What does the Maxwell- Boltzmann distribution show

A
  • the energy in gas particles
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Why do gas particles move at different speeds

A
  • because they have different amounts of kinetic energy
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Describe how a Maxwell-Boltzmann distribution graph looks

A
  • y axis= number of molecules
  • x axis= kinetic energy
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Describe the characteristics of a Maxwell- Boltzmann distribution graph

A
  • starts a 0,0 as NO particle has 0 kinetic energy
  • the area under the curve= the total number of molecules
  • the peak of the graph shows the most likely energy of a particle
  • to the right of the most likely energy is the mean energy of the particles
  • activation energy is on the right hand side of
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What 4 things affects the rate

A

1) Temperature
2) Pressure
3) Concentration
4) Catalysts

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

How does high temperature affect rate

A
  • particles have greater kinetic energy when heated
  • larger proportion of the molecules will have energy greater than the activation energy
  • large area under the curve is beyond the activation energy
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Describe a Maxwell-Boltzmann distribution graph when temperature is higher

A
  • curve shifts to the right
  • peak is lower
  • bigger area under activation energy
  • area under the cure is the same
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

How does low temperature affect rate

A
  • a smaller proportion of molecules will have the energy equal or greater than the activation energy
  • small area under the curve beyond activation energy
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Describe a Maxwell-Boltzmann distribution graph when temperature is low

A
  • curve shifts right
  • peak is higher
  • area under curve is the same
  • area under curve beyond activation energy decreases
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Why do we get a faster rate of reaction when temperature is increased

A
  • particles move around more at higher temperatures ad they have more kinetic energy
  • so they increase the frequency of collisions therefore increasing the frequency of successful collisions
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

How does increase in pressure affect rate

A
  • INCREASES RATE:
  • particles are closer together and so they will collide more often
  • as there are more frequent collisions there is a higher chances of successful collisions
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

How does increase in concentration affect rate

A
  • INCREASE RATE OF REACTION:
  • there are more particles per volume so the particles can collide more frequently
  • more frequent collisions means there is higher rates of successful collisions so higher chance of reactions
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What are catalyst

A
  • a substances that increases the rate of a reaction by providing an alternative pathway that has a lower activation energy. The catalyst is chemically unchanged at the end of the reaction
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Why are catalyst useful

A
  • they make products faster and can be used to lower the temperature
  • which save energy and money
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What are the 2 types of catalysts

A

1) homogenous
2) heterogenous

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What are heterogenous catalysts

A
  • a catalyst that is in a different state from the reactants
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What as an example of the use of heterogenous catalyst

A
  • Haber process:
  • uses a solid iron catalyst
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is an advantage of heterogenous catalysts

A
  • increases the surface area of the catalyst which will increase the rate of reaction as more particles can react with he catalyst at the same time
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What is homogenous catalysts

A
  • a catalyst that is in the same state as the reactants
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

How do homogenous catalysts work

A
  • the catalyst forms a intermediate species by the reactants combining with the catalyst which react to form products
  • catalyst is reformed again
27
Q

How do heterogenous catalysts work

A
  • the reactants stick to the catalyst them dissolve and move away
28
Q

How would a catalyst affect the Maxwell-Boltzmann distribution graph

A
  • add another line behind the activation energy as it would decrease it
  • so more particles would have enough energy to react
29
Q

How would a catalyst affect an energy profile diagram

A
  • lower curve
    -shorter energy profile
30
Q

Why do we uses catalysts

A

1) lower the temp=> less money and less CO2 produced
2) speed up reaction=> provides an alternative pathway so less time
3) change the properties of a product

31
Q

What are the environmental benefits of using a catalyst

A

1) lower temp and pressure=> reduces energy and CO2 produced
2) less waste produced=> as there is better atom economy

32
Q

What are catalytic converters

A
  • used in cars
  • reduce levels of pollution
  • made of rhodium, platinum and palladium alloy
33
Q

What is one way we can measure rates experimentally and what is the issue of this

A
  • MEASURE HOW LONG IT TAKES FOR A PRECIPITATES TO FORM:
  • place a cross on paper and time how long it takes for the cross to disappear (precipitate to form)
    *difficult to know when, exactly the cross disappears it is very subjective
34
Q

What is one way we can measure rates experimentally

A
  • AMOUNT OF MASS LOST:
  • for a reaction that produces a gas
  • place ration on a balance and measure the mass loss as a gas is lost
    *accurate method
35
Q

What is one way we can measure rates experimentally

A
  • VOLUME OF GAS PRODUCED:
  • if a gas is produced
  • measure the amount of gas using a gas syringe over a specific time
36
Q

How do you find the rate from a graph

A
  • from the gradient
37
Q

How do you work out the gradient

A

change in y
———————
change in x

38
Q

When we have a curves line how do we work out the rate

A
  • gradient of a tangent
39
Q

Explain how you find the gradient from the tangent of a curve

A

1) draw a tangent at a specific point
2) extend the line right across the graph
3) work out the gradient

40
Q

What are reversible reactions

A
  • where a reaction can go forward and backwards
41
Q

How do forward reactions initially react

A
  • quickly but then they react slower as their concentration drops
42
Q

How do backward reactions initially react

A
  • reformed slowly but then they speeed up as the concentration of products increase
43
Q

What does a product reactant graph with concentration time look like

A
44
Q

What is a dynamic equilibrium

A
  • the rate of the forward reaction is equal to that of the backward reaction
45
Q

Complete the sentence:
The concentrations of the products and reactants in reversible reactions…

A
  • remain constant
46
Q

What type of systems do dynamic equilibrium occur in

A
  • closed systems
47
Q

What does position of equilibrium describe

A
  • the composition of the equilibrium mixture
  • if the position favours the reactants then the it is said to be “towards the left”
48
Q

What does Le Chatelier’s principle state

A
  • that when a system in dynamic equilibrium is subjected to an external change, the system readjusts itself to minimise the effect of the change and to restore equilibrium
49
Q

What affect would chaining the concentration have according to Le Chatelier’s principle

A
  • if we increase the concentration of a reactant OR product the equilibrium will shift to try and reduce the concentration (opposite will happen if concentration is decreased)
50
Q

What type of equilibria does Le Chatelier’s principle of changing concentration, pressure and temperature work in

A
  • Homogenous equilibria
51
Q

What affect would chaining the pressure have according to Le Chatelier’s principle

A
  • if we increase the pressure the equilibrium will SHIFT to try and reduce the pressure (the opposite happens if pressure decreases)
  • if we increase the pressure the equilibrium will shift to the side with the FEWEST NUMBER OF GAS PARTICLES
52
Q

What affect would chaining the temperature have according to Le Chatelier’s principle

A
  • if we increase the temperature the equilibrium will shift to try to reduce the temperature ( the opposite will happen if temperature is decreased)
53
Q

If we increase the temperature where the forward reaction is exothermic, where will the equilibrium shift and why

A
  • to the endothermic direction as this will reduce the temperature
54
Q

What factors can cause an affect according to Le Chatelier’s principle

A

1) Temperature
2) Concentration
3) Pressure

55
Q

What affect do catalysts have according to Le Chatelier’s principle

A
  • they have NO EFFECT on the position of equilibrium
  • catalysts speed up the rate at which equilibrium is established as it speeds up the rate of forward and backward reaction equally
56
Q

Do catalysts have an effect on yield

A
  • NO
57
Q

Describe comprises made in the haber reaction:
N2 + 3H2 <=> 2NH3 ^H= -ve (exo)
T= 450 degrees Celsius
P= 200- 1000atm catalyst= iron

A
  • low temp gives a good yield but a slow rate so there is a compromise on the temp
  • high pressure gives good yield and high rate but pressures to high would lead to too high energy costs for pumps to produce the pressure
  • catalysts speed up the rate allowing for lower temperatures to be used (meaning lower energy costs) but has no effect on equilibrium
58
Q

What is Kc

A
  • the equilibrium constant
59
Q

Write a Kc equation for the reaction:
2A + B <=> 2C + D

A

Kc= [C]^2 [D]
—————-
[A]^2 [B]
* always products over reactants

60
Q

What affects the value of Kc

A
  • temperature
61
Q

How does temperature affect the Kc

A
  • Kc is only valid for one temperature
  • changing the temperature will change the equilibrium concentrations and so Kc will also change
62
Q

What happens to Kc if temperature change causes the equilibrium to shift right

A
  • Kc will INCREASE
63
Q

What happens to Kc if temperature change causes the equilibrium to shift left

A
  • Kc will DECREASE

Chapter 10=> Reaction Rates And Equillbrium (1 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions