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GCSE Chemistry > Rates of Reaction (Paper 2) > Flashcards

Rates of Reaction (Paper 2) Flashcards

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1
Q

What is meant by rate of reaction

A

How quickly reactants turn into products

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2
Q

Phrase used to describe how quickly reactants turn into products

A

Rate of reaction

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3
Q

2 things to measure when calculating rate of reaction

A

How quickly the reactant is used up
How quickly the product is produced

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4
Q

True or false, some reactions can take years or decades

A

True (e.g rusting of iron)

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5
Q

True or false, some reactions take place in just a fraction of a second

A

True e.g fireworks

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6
Q

Equation to measure how fast the reactants are being used up (rate of reaction)

A

Quantity of reactants used/ time taken

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7
Q

Measuring how quickly the reactant is used up/ how quickly the product Is formed are 2 different ways to tell you the…

A

Rate of reaction

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8
Q

Equation to measure how quickly the product is formed (rate of reaction)

A

Quantity of product formed/ time taken

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9
Q

When measuring rate of reaction, what is the quantity (of reactant/ product) measured in

A

Grams or cm cubed

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10
Q

When measuring rate of reaction, what is time taken measured in

A

Seconds

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11
Q

Do reactions start of fast and slow down or slow and speed up

A

Start fast but slow down
(That’s why when measuring rate of reaction it’s only an average)

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12
Q

When drawing graphs showing rate of reaction, what goes on the x axis

A

Time (in seconds)

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13
Q

When drawing graphs showing rate of reaction what goes on the y axis

A

Mass of reactant used/ product formed (g or cm cubed)

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14
Q

5 factors affecting rate of reaction

A

Surface area
Temperature
Concentration
(Absence/ presence of) catalyst
Pressure of gases

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15
Q

What is meant by collision theory

A

In order to react, particles must collide with sufficient energy

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16
Q

Name for theory where in order to react, particles must collide with sufficient energy

A

Collision theory

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17
Q

The collision theory states that in order to… particles must…with sufficient…

A

React, collide, energy

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18
Q

Name for minimum amount of energy needed for particles to collide with each other and react

A

Activation energy

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19
Q

What is activation energy

A

Minimum amount of energy needed for particles to collide with each other and react

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20
Q

How temperature increases rate of reaction

A

As temperature increases, particles gain more kinetic energy and move faster so there are more frequent collisions and they will collide with more energy so more of the collisions are successful

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21
Q

Both concentration and pressure refer to how many particles there are per unit of…

A

Volume

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22
Q

How increasing pressure/ concentration increases rate of reaction

A

Increasing pressure/ concentration means that there are more particles per unit of volume so more frequent collisions which increases rate of reaction

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23
Q

How increasing surface area increases rate of reaction

A

The greater the surface area, the more particles there are that are exposed, so more frequent collisions which increases rate of reaction

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24
Q

What is a catalyst

A

Something that speeds up the rate of reaction without being used up

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25
Q

Why aren’t catalysts used in the reaction equation

A

They aren’t reactants or products

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26
Q

What do catalysts do to the activation energy

A

Lower it
(Particles need less energy to collide and react)

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27
Q

A catalyst provides an alternative… which lowers the activation energy reaction

A

Pathway

28
Q

How to calculate rate of reaction at a particular time using graph

A

Draw tangent at particular time you’re interested in and measure gradient

29
Q

When writing an equation what does the double arrow mean

A

The reaction is reversible

30
Q

How to represent reaction being reversible when writing an equation

A

Use double arrow
(not single one)

31
Q

In a reversible reaction we call the top arrow the… reaction

A

Forward

32
Q

In a reversible reaction we call the bottom arrow the… reaction

A

Backward

33
Q

True or false, in a reversible reaction both the forward and backward reaction can happen

A

True

34
Q

True or false, in a reversible reaction the forward and backward reactions can take place at different rates

A

True

35
Q

Dynamic equilibrium meaning

A

Point in reversible reaction where the forward and backward reaction are at the same rate in a closed system

(Both reactions are happening but they basically cancel each other out)

36
Q

True or false, in dynamic equilibrium the amount of reactant and product are always equal

A

False
They are always constant but not necessarily the same as each other

37
Q

Equilibrium can only be reached if the reaction is done in what type of system

A

Closed system

38
Q

True or false, in a closed system no reactants or products can escape

A

True

39
Q

True or false, at equilibrium the reactants are still turning into products and products still turning back into reactants

A

True- it’s just at the same rate so the amount of reactants and products are constant (not necessarily equal)

40
Q

True or false, equilibrium can only be reached if the reaction is done in a closed system

A

True
Otherwise the reactants/ products could keep escaping

41
Q

True or false, reversible reactions are always exothermic in one direction and endothermic in the other direction

A

True

42
Q

Hydrated meaning

A

Water is present

43
Q

Anhydrous meaning

A

No water is present

44
Q

True or false, the position of equilibrium can change (shift to left/ right) depending on conditions

A

True

45
Q

Le Chatelier’s principle is about the position of what during a reversible reaction

A

Equilibrium

46
Q

3 main ways to change conditions of closed system

A

Temperature
Pressure
Concentration

47
Q

If there are more reactants than products does the equilibrium lie to the left or right

A

Left

48
Q

If there are more products than reactants does the equilibrium lie to the left or right

A

Right

49
Q

Why do exothermic reactions have an overall negative energy change

A

Energy is released to surroundings so lost

50
Q

Why do endothermic reactions have an overall positive energy change

A

Take in energy from surrounds so energy is gained (added)

51
Q

What is a reversible reaction

A

Reaction where reactants can turn into products and products can turn back into reactants

52
Q

What is meant by Le Chatelier’s principle

A

If a change is made to a system that’s at dynamic equilibrium, the system will try to undo (counteract) the change by favouring either the forward or reverse reaction so that it stays at dynamic equilibrium

53
Q

If the concentration of the product is lowered, which reaction will the system favour and why

A

Forward reaction
Forward reaction turns reactants into products and the way to counteract a decreased product concentration is to increase it

54
Q

If I increase the temperature what will the system do and how

A

Decrease temperature
Favour endothermic reaction which decreases temperature so moves towards endothermic

55
Q

If I decrease the temperature what will the system do and how

A

Increase temperature by favouring (moving towards) exothermic reaction which increases temperature

56
Q

If I increase concentration what will the system do

A

Decrease concentration by moving towards reaction that removes that chemical

57
Q

If I decrease concentration what will the system do

A

Move towards reaction that produces that chemical

58
Q

If I increase pressure what will the system do

A

Decrease pressure by favouring reaction that produces fewest molecules

59
Q

If I decrease pressure what will the system do

A

Increase pressure by favouring reaction that produces greatest number of molecules

60
Q

2 units for rate of reaction

A

g/s
Cm cubed/ s

(as the quantity of reactant used/ product formed can either be measured in grams or cm cubed and time is always in seconds)

61
Q

5 examples of evidence for a chemical reaction occurring

A

Change in colour
Change in temperature
Bubbles/ fizzing
Precipitate (solid) formed
Odours/ sounds

62
Q

What do particles do if they don’t have enough energy to react

A

Bounce off each other

63
Q

Why does the rate of reaction decrease towards the end

A

Reactants becoming used up so less frequent collisions

64
Q

How can we tell on a graph where the rate of reaction is highest

A

Steepest gradient

65
Q

If the temperature of a reversible reaction is raised, what happens to the yield from the exothermic reaction

A

It decreases

GCSE Chemistry (18 decks)

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