6. The Rate and Extent of Chemical Change

studied byStudied by 0 people
0.0(0)
learn
LearnA personalized and smart learning plan
exam
Practice TestTake a test on your terms and definitions
spaced repetition
Spaced RepetitionScientifically backed study method
heart puzzle
Matching GameHow quick can you match all your cards?
flashcards
FlashcardsStudy terms and definitions

1 / 106

encourage image

There's no tags or description

Looks like no one added any tags here yet for you.

107 Terms

1

Collision Theory (using bullet points - )

-Must collide with activation energy to be successful (if not particles bounce off each other with no successful collisions so no reaction occurs)

-RATE OF REACTION depends on two things: how frequently and forcefully particles collide.

-if frequency and forcefulness are changed, RATE OF REACTION will change

New cards
2
<p>Collision Theory explanations: Label A, B, and C in terms of <strong>collision theory</strong><br><br>*This is accurate for <strong>any fizzy reaction</strong></p>

Collision Theory explanations: Label A, B, and C in terms of collision theory

*This is accurate for any fizzy reaction

A: many reacting particles, very frequent collisions

B: fewer reacting particles, less frequent collisions

C: no more reacting particles as one reactant has been used up

New cards
3
<p>Label A, B and C (<strong>not</strong> collision theory)<br><br>*This is accurate for <strong>any fizzy reaction</strong></p>

Label A, B and C (not collision theory)

*This is accurate for any fizzy reaction

A: Reaction fastest (steepest gradient)

B: Reaction slowing (less steep gradient)

C: Reaction stops

New cards
4

Rate of Reaction definition

the change in amount of substance per second

New cards
5

To find mean rate

read off graph and divide y/x

New cards
6

To find mean rate using a tangent

Draw tangent, turn into triangle, divide y/x

New cards
7

Gas Syringe Method definition

The gas syringe is used to collect and measure the amount of gas produced during a reaction from a conical flask.knowt flashcard image

New cards
8

Gas Syringe Method Advantages

Good Resolution, Gases are not released into the room.

New cards
9

Gas Syringe Method Monitoring Options

Either decide time and measure volume or decide volume and measure time or measure at intervals.

New cards
10


Mass Loss method definition

MEASURES GAS: Use scales to measure how much mass is lost with conical flask and cotton wool ball (only allows gas to escape, not liquid).C6 B) Rate of Reaction – AQA Chemistry - Elevise

New cards
11

Mass Loss method advantages

Excellent resolution: masses measured to the nearest 0.01g

New cards
12

Mass Loss method disadvantages

Gases are released into the room

New cards
13

Mass Loss method monitoring options

Either choose time and measure mass loss or choose mass loss and measure time. Or measure at regular time intervals.

New cards
14

Monitoring Rate of Reactions that don’t produce gas: DEFINITION

If no gas is produced and reaction produces a precipitate or dark colour, time how long it takes for a cross on piece of paper to disappear.

New cards
15

Conical Flask

knowt flashcard image

New cards
16

Precipitate

A solid formed by change in solution.

New cards
17

What factors affect rate

Surface Area, Concentration, Pressure, Temperature

New cards
18

Repeatable

I do it lots and get the same results

New cards
19

Reproducable

Others do it lots and get the same results

New cards
20

In the order Concentration, Surface Area, Pressure, Temperature how do these factors effect rate?

Concentration: Higher concentration, faster rate of reaction
Surface Area: Larger surface area, faster rate of reaction.
Pressure: Increased pressure, faster rate of reaction.

Temperature: Increased temperature increases rate of reaction.

New cards
21

How is pressure caused?

Gas particles colliding with container walls

New cards
22

When does a reaction stop?

When one reactant has been used up so there are no more collisions.

New cards
23

Independent Variable

What I change

New cards
24

Dependent Variable

What I observe

New cards
25

Controlled Variable

What I keep the same

New cards
26

Explain, in terms of particles, why rate of reaction increases with temperature.

-Temperature increase means particles have more energy
-Particles have activation energy
-More frequent collisions

-More forceful collisions

New cards
27

What does a Catalyst do?

Provides a new route for a reaction with lower activation energy so particles can collide more frequently

particles HAVE NOT got more energy!! ONLY

temperature increase can do this

New cards
28

Who are the best catalysts?

Transition metals (specifically manganese oxide) and their compounds

New cards
29

Advantages of using a catalyst + explanations

Reactions done at lower temperatures
-less non-renewable fossil fuels used

-less CO2 emissions, less global warming

-less SO2 emissions, less acid rain

-less NOx emissions, less acid rain

-less particulates, less global dimming and lung diseases

Sustainable

-less non-renewable sources of metal catalyst used

-less mining of metal catalyst, less habit destruction

New cards
30

Disadvantages of using a catalyst + explanations

Fill up landfill sites on disposal:
-they do not decompose/rot
-can contain toxic poisons that enter environment
Eventually stop working so mining of metal catalysts:
-expensive to mine/extract
-rare metals are very expensive to mine/extract

New cards
31

floating head reaction
RP: Sodium Thiosulphate-HCl Reaction
Important information

-no gas produced in this reaction so we cannot use a gas syringe or a balance to monitor it
-A yellow precipitate of sulphur is produced (S(s))
-we measure time taken for the cross to dissapear

New cards
32

floating head reaction
RP: Sodium Thiosulphate-HCl Reaction
What is it used for?

Any reaction that produces a precipitate or a dark colour

New cards
33

floating head reaction
RP: Sodium Thiosulphate-HCl Reaction

Variables

IV: Concentration of ‘thio’
DV: Time for cross to disappear
CV: Concentration of HCl
Volume of HCl

Total volume of ‘thio’
Constant Temperature

New cards
34

floating head reaction
RP: Sodium Thiosulphate-HCl Reaction
Accuracy

To improve accuracy
-use pipette or burette to measure vol

-use light sensor connected to a data logger to measure when light intensity drops to a certain value (as precipitate forms)
-use water bath set at fixed temp to keep contents in a flask at a constant temperature

New cards
35

Calcium Carbonate (marble) or Magnesium HCl reaction
Methods

-Measure gas volume with a gas syringe

-Measure mass loss using a balance

New cards
36

Calcium Carbonate (marble) or Magnesium HCl reaction
Variables

IV: Concentration of HCl
DV: Time for cross to disappear
CV: Total voume of HCl
Same mass of solid
Constant room temperature

New cards
37

Calcium Carbonate (marble) or Magnesium HCl reaction
Accuracy

To improve accuracy:
-use pipette or burette to measure volume

-use water bath set at fixed temp to keep contents at a constant temp.

New cards
38

How to prove a Catalyst can not be used up

-weigh catalyst

-filter mix

-dry catalyst

-reweigh cat.

New cards
39

Endothermic

reactants absorb heat energy from the surroundings to form products

New cards
40

Exothermic

releases heat, causing the temperature of the immediate surroundings to rise

New cards
41
<p>Volume/Mass Loss vs time graph</p>

Volume/Mass Loss vs time graph

Lower Concentration: Slower (less steep) and less gas produced
Halving concentration: halves volume/ mass gas produced

New cards
42

Concentration mathematical link

-Rate directly proportional to concentration (rate ∝ concentration)
e.g if doubling conc doubles rate
twice as many reacting particles
twice as many frequent collisions

New cards
43

Temperature mathematical link

-Rate is NOT directly proportional to temperature
-Rate approximately doubles per 10 degree rise

New cards
44

More diluted solution means

Less gas produced (less steep line, finishes later)

New cards
45

Change in surface area

Does not change how much gas is produced, just gives a much faster reaction

New cards
46

Surface area mathematical link

-rate is directly proportional to surface area

-e.g doubling surface area doubles rate
twice as many reacting solid particles available

twice as many frequent collisions

New cards
47

Pressure mathematical link

-rate directly proportional to pressure
-e.g doubling pressure doubles rate
same number of particles in half the volume
twice as many frequent collisions

New cards
48

Straight line through origin

Directly proportional

New cards
49

Change in temperature

Does not change amount of gas produced, just gives a faster reaction

New cards
50
<p>Change in temperature graph</p>

Change in temperature graph

Not straight line through the origin:

Rate is not directly proportional to temperature
Pattern is called ‘exponential’

New cards
51

‘exponential’

increase one thing by a certain amount each time (eg 10 degrees)

other ‘thing’ increases by more and more each time
(eg by 2, then 7, then 25 etc)

New cards
52

The most common reactions that produce gas

Adding metal to an acid to produce H2 gas
for example:

Magnesium + Hydrochloric Acid → Magnesium Chloride + Hydrogen

Adding a carbonate to an acid to produce CO2 gas
for example:
Calcium Carbonate + Hydrochloric Acid → Calcium Chloride + Carbon Dioxide + Water

New cards
53

The rate of any reaction that produces a gas

can be measured by mass loss or gas volume methods

New cards
54

A successful collision means

bonds are broken in reactants

the particles separate from each other

they combine differently

new bonds form between them to make the products

New cards
55

Making catalysts even better

-Powdered Catalysts: Large Surface Area, Reactions go even faster
-Nanocatalysts: Huge surface area to volume ratio (huge surface area compared to volume)

New cards
56

Catalysts and rate

Hydrogen Peroxide solution (aq) breaks down very slowly. Can be sped up using a catalyst.

New cards
57

What factors affect rate

Surface Area, Concentration, Pressure, Temperature

New cards
58

Repeatable

I do it lots and get the same results

New cards
59

Reproducable

Others do it lots and get the same results

New cards
60

Collision Theory

Many reacting particles, more frequent collisions

New cards
61

Concentration

Higher concentration, faster rate of reaction.

New cards
62

Surface Area

Larger surface area, faster rate of reaction.

New cards
63

Pressure

Increased pressure, faster rate of reaction.

New cards
64

How is pressure caused?

Gas particles colliding with container walls

New cards
65

Temperature

Increased temperature, faster rate of reaction.

New cards
66

GRAPHS: Fast (steep gradient)

Many reacting particles, very frequent collisions

New cards
67

GRAPHS: Slower (less steep gradient)

Fewer reacting particles, less frequent collisions.

New cards
68

When does a reaction stop?

When one reactant has been used up so there are no more collisions.

New cards
69

Gas Syringe Method definition

The gas syringe is used to collect and measure the amount of gas produced during a reaction from a conical flask.

<p>The gas syringe is used to collect and measure the amount of gas produced during a reaction from a conical flask.</p>
New cards
70

Gas Syringe Method Advantages

Good Resolution, Gases are not released into the room.

New cards
71

Gas Syringe Method Disadvantages

Very fast reaction could make the plunger shoot out and break.

New cards
72

Gas Syringe Method Monitoring Options

Either decide time and measure volume or decide volume and measure time or measure at intervals.

New cards
73

Mass Loss method definition

MEASURES GAS: Use scales to measure how much mass is lost with conical flask and cotton wool ball (only allows gas to escape, not liquid).

New cards
74

Mass Loss method advantages

Excellent resolution: masses measured to the nearest 0.01g

New cards
75

Mass Loss method disadvantages

Gases are released into the room

New cards
76

Mass Loss method monitoring options

Either choose time and measure mass loss or choose mass loss and measure time. Or measure at regular time intervals.

New cards
77

Monitoring Rate of Reactions that don’t produce gas: DEFINITION

If no gas is produced and reaction produces a precipitate or dark colour, time how long it takes for a cross on piece of paper to disappear.

New cards
78

Conical Flask

knowt flashcard image
New cards
79

Precipitate

A solid formed by change in solution.

New cards
80

Magnesium + Hydrochloric Acid →

Mg(s) + 2HCl(aq) →

Magnesium Chloride + Hydrogen

MgCl2(aq) + H2(g)

New cards
81

Magnesium + Sulphuric Acid →

Mg(s) + H2SO4(aq) →

Magnesium Sulphate + hydrogen

MgSO4(aq) + H2(g)

New cards
82

Calcium Carbonate + Hyrdrochloric Acid →

CaCO3(s) + 2HCl(aq) →

Calcium Chloride + Carbon Dioxide + Water

CaCl2(aq) + CO2(g) + H2O(l)

New cards
83

Collision Theory Definition

For reactions to occur, particles must collide successfully.

New cards
84

What is a successful collision?

Particles must collide, with sufficient energy, and with the correct orientation.

<p>Particles must collide, with sufficient energy, and with the correct orientation. </p>
New cards
85

Activation Energy (E with subscript A)

Minimum energy particles must have to react

New cards
86

Rate of Reaction

How frequently particles collide and how hard they hit each other (collision energy)

New cards
87

To find mean rate

Read off graph at time given and then divide y/x

New cards
88

To find rate using a tangent

Draw tangent, turn into triangle, divide y/x

New cards
89

Reversible reaction

products can react to produce original reactants

direction can be changed by changing conditions

same amount of energy transferred each way (one way energy lost, one gained)

New cards
90

If reaction is exothermic one way..

endothermic the other

New cards
91

Equilibrium

When a reversible reaction occurs in a closed system, equilibrium is reached when the reactions occur at exactly the same rate in each direction.

New cards
92

Le Chatelier’s law

an equilibrium will react to oppose changes made to it

New cards
93

if substance added to equilibrium,

if we add something to one side, it gets used up

so more of the other side forms (the opposite side is favoured)

new equilibrium established

<p>if we add something to one side, it gets used up</p><p>so more of the other side forms (the opposite side is favoured)</p><p>new equilibrium established</p>
New cards
94

Equilibrium: Adding extra A or B

-A or B is used up

-forward reaction is favoured so more C, D &amp; E will form

(equilibrium has moved to RHS)

-a new equilibrium is established

<p>-A or B is used up</p><p>-forward reaction is favoured so more C, D &amp;amp; E will form</p><p>(equilibrium has moved to RHS)</p><p>-a new equilibrium is established</p>
New cards
95

Equilibrium: adding extra C, D, E

-C/D/E is used up

-reverse reaction is favoured so more A & B will form

(equilibrium has moved to LHS)

-a new equilibrium is established

<p>-C/D/E is used up</p><p>-reverse reaction is favoured so more A &amp; B will form</p><p>(equilibrium has moved to LHS)</p><p>-a new equilibrium is established</p>
New cards
96

removing substances from an equilibrium

if we remove something from one side, it is brought back

so the side we remove from is favoured

New cards
97

equilibrium: removing A or B

-reverse reaction (LHS) is favoured so C, D & E react

-to restore A/B (the equilibrium has moved to LHS)

-a new equilibrium is established

New cards
98

equilibrium: removing C, D or E

-forward reaction (RHS) is favoured so A & B react

-to restore C/D/E (the equilibrium has moved to RHS)

-a new equilibrium is established

New cards
99

changing temperature of an equilibrium

cool an equilibrium: more ‘hot side’ is made

warm an equilibrium up: more ‘cold side’ is made

New cards
100
<p>The forward reaction is exothermic (Z gives out heat)</p><p>increase temperature </p>

The forward reaction is exothermic (Z gives out heat)

increase temperature

-increasing temperature favours endothermic (reverse) reaction (LHS)

-more X &Y (less Z) forms (equilibrium moved to LHS)

-a new equilibrium is established

New cards

Explore top notes

note Note
studied byStudied by 6 people
663 days ago
5.0(1)
note Note
studied byStudied by 3 people
28 days ago
5.0(1)
note Note
studied byStudied by 13 people
856 days ago
5.0(1)
note Note
studied byStudied by 520 people
170 days ago
4.5(2)
note Note
studied byStudied by 3 people
38 days ago
5.0(1)
note Note
studied byStudied by 14 people
707 days ago
5.0(2)
note Note
studied byStudied by 37 people
869 days ago
5.0(1)
note Note
studied byStudied by 23695 people
704 days ago
4.8(93)

Explore top flashcards

flashcards Flashcard (98)
studied byStudied by 1 person
829 days ago
5.0(1)
flashcards Flashcard (27)
studied byStudied by 7 people
38 days ago
5.0(1)
flashcards Flashcard (23)
studied byStudied by 27 people
429 days ago
5.0(1)
flashcards Flashcard (44)
studied byStudied by 7 people
789 days ago
5.0(1)
flashcards Flashcard (35)
studied byStudied by 10 people
731 days ago
5.0(2)
flashcards Flashcard (107)
studied byStudied by 4 people
155 days ago
5.0(1)
flashcards Flashcard (21)
studied byStudied by 48 people
544 days ago
5.0(1)
flashcards Flashcard (32)
studied byStudied by 79 people
755 days ago
5.0(3)
robot