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Chemistry ~ Paper 2 > The Rate And Extent Of Chemical Change > Flashcards

The Rate And Extent Of Chemical Change Flashcards

1
Q

What is the rate of a chemical reaction?

A

The rate of a chemical reaction is how fast the reactants are changed into products.

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2
Q

What is one of the slowest chemical reactions mentioned?

A

The rusting of iron.

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3
Q

Give an example of a moderate speed reaction.

A

The reaction of magnesium with an acid producing a gentle stream of bubbles.

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4
Q

What type of reaction is burning classified as?

A

A fast reaction.

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5
Q

What is the fastest type of reaction mentioned?

A

Explosive reactions.

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6
Q

How can you find the speed of a reaction?

A

By recording the amount of product formed or the amount of reactant used up over time.

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7
Q

What does a steeper line on a reaction graph indicate?

A

A faster rate of reaction.

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8
Q

What happens to the line on a graph as reactants are used up?

A

The line becomes less steep.

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9
Q

What does it indicate if multiple graphs converge at the same level?

A

They all produce the same amount of product.

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10
Q

What is collision theory?

A

It explains that the rate of a chemical reaction depends on the collision frequency of reacting particles and the energy transferred during a collision.

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11
Q

What is activation energy?

A

The minimum amount of energy that particles need to react.

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12
Q

Name one factor that affects the rate of reaction.

A

Temperature, concentration of a solution, surface area, or the presence of a catalyst.

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13
Q

How does increasing temperature affect the rate of reaction?

A

Particles move faster and collide more frequently, leading to more successful collisions.

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14
Q

What happens when the concentration of a solution is increased?

A

There are more particles in the same volume, increasing collision frequency.

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15
Q

How does increasing surface area affect reaction rate?

A

It increases the surface area to volume ratio, leading to more frequent collisions.

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16
Q

What is a catalyst?

A

A substance that speeds up a reaction without being used up.

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17
Q

How do catalysts work?

A

By providing an alternative reaction pathway with a lower activation energy.

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18
Q

What are enzymes?

A

Biological catalysts that catalyse reactions in living things.

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19
Q

Fill in the blank: The rate of reaction depends on _______.

A

Temperature, concentration, surface area, and the presence of a catalyst.

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20
Q

True or False: A catalyst is consumed in the reaction.

A

False.

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21
Q

What is the formula for calculating the rate of a reaction?

A

Rate of Reaction = Amount of reactant used or amount of product formed / Time

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22
Q

What units can be used to measure the rate of a reaction involving gases?

A

cm³, mol/s

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23
Q

What units can be used to measure the rate of a reaction involving solids?

A

g/s

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24
Q

What is the first method for measuring the rate of a reaction?

A

Precipitation and Colour Change

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25
How can you observe a precipitation reaction?
Record the visual change when a transparent solution becomes opaque
26
What is a subjective method for measuring the rate of a reaction?
Timing how long it takes for a mark to disappear through a solution
27
What is the second method for measuring the rate of a reaction?
Change in Mass (Usually Gas Given Off)
28
How is the speed of a reaction producing gas measured?
Using a mass balance to measure the mass loss
29
What is the third method for measuring the rate of a reaction?
The Volume of Gas Given Off
30
What equipment is typically used to measure the volume of gas produced in a reaction?
Gas syringe
31
True or False: The quicker the mass reading drops on a balance, the faster the reaction.
True
32
Fill in the blank: To measure the rate of reaction between solid Na2CO3 and aqueous HCl, one could use a _______.
mass balance
33
In the magnesium and HCl experiment, what must be kept constant?
The amount of magnesium ribbon and the volume of acid
34
What happens when the concentration of acid increases in the magnesium and HCl reaction?
The rate of reaction increases
35
What is produced when sodium thiosulfate and HCl react?
A yellow precipitate of sulfur
36
How is the time taken for a reaction measured in the sodium thiosulfate experiment?
By timing how long it takes for a black cross to disappear
37
What safety consideration should be taken when conducting the sodium thiosulfate and HCl experiment?
Carry out in a well-ventilated place
38
What should be done to ensure a fair test in reaction experiments?
Only change the concentration of one reactant at a time
39
What does increasing the concentration of HCl do to the time taken for the black cross to disappear?
It decreases the time taken
40
What type of graph can be plotted from the results of the magnesium and HCl experiment?
A graph with time on the x-axis and loss of mass on the y-axis
41
Fill in the blank: The method of measuring the rate of a reaction by observing color change is known as _______.
Precipitation and Colour Change
42
What is a disadvantage of using a mass balance to measure gas production?
Gas is released into the room
43
True or False: Different people may agree on the exact point when a mark disappears in a visual reaction test.
False
44
What does a rate of reaction graph show on the y-axis?
The amount of product formed or amount of reactant used up ## Footnote This graph is essential for calculating reaction rates.
45
How do you calculate the mean rate of reaction from a graph?
Overall change in y-value ÷ total time taken for the reaction ## Footnote This gives the average rate of reaction over the entire time interval.
46
What is the formula to find the mean rate of reaction between two points in time?
Mean rate of reaction = change in y ÷ change in x ## Footnote Example: (19 cm³ - 15 cm³) ÷ 20 s = 0.2 cm³/s.
47
What does the tangent of a curve represent in reaction rate graphs?
The rate of the reaction at a particular point in time ## Footnote Finding the gradient of the tangent gives the reaction rate at that specific moment.
48
How do you calculate the gradient of a tangent?
Change in y ÷ change in x ## Footnote Example: (2.2 - 1.4) ÷ (5.0 - 2.0) = 0.27 g/min.
49
What is a reversible reaction?
A reaction that can go backwards ## Footnote The products can react to form the reactants again.
50
What happens to the concentrations of reactants and products in a reversible reaction as they react?
The concentrations of reactants fall and products rise ## Footnote This dynamic leads to changes in the rates of the forward and backward reactions.
51
What is dynamic equilibrium?
Both reactions are still happening, but there's no overall effect ## Footnote At this point, the concentrations of reactants and products are balanced.
52
What conditions must be met for equilibrium to be reached in a reversible reaction?
The reaction must take place in a closed system ## Footnote This means that no reactants or products can escape.
53
What does it mean if the equilibrium lies to the right?
The concentration of products is greater than that of the reactants ## Footnote This indicates a shift in favor of product formation.
54
What factors affect the position of equilibrium?
Temperature, pressure (for gas equilibria), concentration of reactants and products ## Footnote Each of these factors can shift the equilibrium position.
55
What happens to the equilibrium position when the temperature is increased in an endothermic reaction?
It moves to the right ## Footnote This results in more products being formed.
56
What is the relationship between endothermic and exothermic reactions in reversible processes?
If one direction is endothermic, the reverse is exothermic ## Footnote Energy transferred from surroundings is equal in both processes.
57
What is an example of a reversible reaction involving hydrated copper sulfate?
Hydrated copper sulfate ⇌ anhydrous copper sulfate + water ## Footnote Heating drives off water (endothermic), adding water restores the hydrated form (exothermic).
58
What does it mean for a system to be at equilibrium?
There is no overall change in the concentrations of reactants and products ## Footnote The system is stable despite ongoing reactions.
59
What is Le Chatelier's Principle?
Le Chatelier's Principle states that if you change the conditions of a reversible reaction at equilibrium, the system will try to counteract that change.
60
How does temperature affect a reversible reaction according to Le Chatelier's Principle?
If you decrease the temperature, the equilibrium moves in the exothermic direction to produce more heat, resulting in more products for the exothermic reaction and fewer for the endothermic reaction.
61
What happens to the equilibrium when the temperature is increased?
If you raise the temperature, the equilibrium moves in the endothermic direction to decrease the temperature, resulting in more products for the endothermic reaction and fewer for the exothermic reaction.
62
How does changing pressure affect equilibrium involving gases?
Changing the pressure affects an equilibrium involving gases by shifting the equilibrium towards the side with fewer molecules of gas when pressure is increased, and towards the side with more molecules of gas when pressure is decreased.
63
In the reaction N2 + 3H2 ⇌ 2NH3, what is the effect of increasing the pressure?
Increasing the pressure shifts the equilibrium to the right, producing more NH3, because there are fewer moles of gas on the right side.
64
What is the effect of increasing the concentration of reactants in a reversible reaction?
Increasing the concentration of reactants causes the system to produce more products to restore equilibrium.
65
What happens when the concentration of products is decreased in a reversible reaction?
Decreasing the concentration of products causes the system to reduce the amount of reactants to restore equilibrium.
66
True or False: An equilibrium will always shift to favor the side with more molecules of gas when pressure is increased.
False
67
Fill in the blank: If you decrease the temperature of a reaction that is exothermic in the forward direction, the equilibrium will shift to the _______.
right
68
What is the significance of control in reversible reactions for industrial processes?
Control in reversible reactions allows for profitable outcomes in industrial processes.

Chemistry ~ Paper 2 (5 decks)

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