Rates Of Reaction & Collision Theory Flashcards
(103 cards)
1
Q
What is the Rate of Reaction?
A
The speed at which a reaction takes place.
2
Q
How can the rate of reaction be measured?
A
By measuring how quickly the reactants are used up and how quickly the products are formed.
3
Q
What are the three main methods to measure the rate of reaction?
A
- Change in mass
- Volume of gas formed
- Formation of a precipitate
4
Q
How does Change in mass method work?
A
The mass of the flask and contents decreases as the gas formed leaves the flask.
5
Q
What does the Volume of gas formed method involve?
A
A gas syringe is used to collect the gas as it is produced during the reaction.
6
Q
How is the Formation of a precipitate method measured?
A
By recording the decrease in light intensity over time as the solution turns milky cloudy.
7
Q
What is Collision Theory?
A
For a reaction to happen, the reacting particles must successfully collide.
8
Q
What is required for a successful collision?
A
The reacting particles must have sufficient energy.
9
Q
What is activation energy?
A
The minimum energy reacting particles must have when they collide for the reaction to take place.
10
Q
What factors can change the rate of a reaction?
A
- Temperature
- Concentration
- Surface area
- Catalyst
11
Q
How does temperature affect the rate of reaction?
A
Increasing the temperature makes the particles move faster and increases the chance of successful collisions.
12
Q
What effect does increasing concentration have on the rate of reaction?
A
It increases the number of reacting particles, leading to a higher chance of successful collisions.
13
Q
How does surface area impact the rate of reaction?
A
A larger surface area provides more space for the reacting particles to collide, increasing the chance of successful collisions.
14
Q
What is the role of a catalyst in a reaction?
A
A catalyst speeds up a reaction without being used up and lowers the activation energy.
15
Q
What does a rate graph show?
A
It is used to follow the course of a reaction and compare the rates of similar reactions.
16
Q
What characterizes a faster reaction on a rate graph?
A
- Higher temperature
- Larger surface area
- Presence of a catalyst
17
Q
What characterizes a slower reaction on a rate graph?
A
- Lower concentration
- Smaller surface area
- Absence of a catalyst
18
Q
What is the rate of a reaction?
A
How quickly reactants are used up or products are produced.
19
Q
What is the equation for calculating the mean rate of reaction?
A
Mean rate = change in quantity of product or reactant / time taken.
20
Q
What is the unit for rate of reaction in a reaction involving a change in mass?
A
g/s
21
Q
What is the unit for rate of reaction in a reaction involving a change in volume?
A
cm/s
22
Q
What is the activation energy?
A
The minimum amount of energy colliding particles have to have before a reaction will take place.
23
Q
What effect does increasing concentration have on the rate of reaction?
A
Increases.
24
Q
Why does increasing concentration have this effect?
A
More reactant particles in the same volume lead to more frequent collisions.
25
What effect does increasing pressure have on the rate of reaction?
Increases.
26
Why does increasing pressure have this effect?
Less space between particles means more frequent collisions.
27
What effect does increasing surface area have on the rate of reaction?
Increases.
28
Why does increasing surface area have this effect?
More reactant particles are exposed and able to collide, leading to more frequent collisions.
29
What effect does increasing temperature have on the rate of reaction?
Increases.
30
Why does increasing temperature have this effect?
Particles move faster, leading to more frequent collisions.
31
What is a catalyst?
A substance that increases the rate of a reaction but is not used up in the reaction.
32
How do catalysts increase the rate of a reaction?
Lower the activation energy of the reaction, so more collisions result in a reaction.
33
What is the term used to describe magnesium in the reaction with hydrochloric acid?
reactant
## Footnote
Reactants are substances that undergo chemical changes in a reaction.
34
How can the rate of a chemical reaction be determined?
by measuring the quantity of reactant used up or the quantity of the products formed over time
## Footnote
This method provides a quantitative measure of the reaction rate.
35
Which factor does not affect the rate of a chemical reaction?
volume
## Footnote
The main factors affecting reaction rates include pressure, surface area, and temperature.
36
According to collision theory, when can chemical reactions occur?
when particles collide with each other with enough energy
## Footnote
Collision theory states that for a reaction to occur, particles must collide effectively.
37
Fill in the blank: The reaction of magnesium with hydrochloric acid produces _______.
magnesium chloride and hydrogen
## Footnote
This is the product of the reaction, demonstrating the transformation of reactants.
38
Which statement is not true about catalysts?
A. catalysts are used up in chemical reactions
## Footnote
Catalysts are not consumed in the reactions they facilitate; they remain unchanged after the reaction.
39
How do catalysts help in chemical reactions?
B. catalysts can help to reduce the cost of large-scale chemical reactions
## Footnote
By lowering the activation energy, catalysts can make reactions more efficient and cost-effective.
40
What do catalysts reduce in chemical reactions?
C. catalysts reduce the activation energy of chemical reactions
## Footnote
This allows reactions to proceed faster at lower temperatures.
41
Why might different chemical reactions require different catalysts?
D. different chemical reactions may need different catalysts
## Footnote
Each reaction has unique characteristics that may require specific catalysts to optimize the reaction rate.
42
Why does increasing the concentration of a reactant increase the rate of a reaction?
B. particles collide more often
## Footnote
Higher concentration leads to more frequent collisions between reactant particles, increasing the likelihood of reaction.
43
Fill in the blank: In a chemical reaction, increasing the concentration of a reactant leads to _______.
increased reaction rate
## Footnote
This occurs due to more frequent collisions among reactant particles.
44
Which reaction was the slowest based on Figure 1?
A. W
## Footnote
The amount of product formed over time indicates that reaction W had the least product formed.
45
Fill in the blank: The amount of product formed over time in chemical reactions can be represented in a _______.
graph
## Footnote
Graphs visually depict the relationship between time and product formation in chemical reactions.
46
How can the mean rate of a reaction be calculated?
mean rate of reaction = quantity of reactant used ÷ time taken
## Footnote
The mean rate of reaction is a fundamental concept in chemistry used to quantify how quickly a reaction occurs.
47
What is the mean rate of reaction if a reaction produces 45cm³ of carbon dioxide in 30 seconds?
1.5cm³/s
## Footnote
Mean rate of reaction is calculated by dividing the volume of product formed by the time taken.
48
How could the rate of reaction between calcium carbonate and sulfuric acid be increased?
grind the calcium carbonate into a powder
## Footnote
Increasing the surface area of reactants can enhance the rate of reaction by allowing more collisions.
49
Which term describes the minimum energy that particles must have to react?
activation energy
## Footnote
Activation energy is a key concept in understanding reaction kinetics and the energy barrier for reactions.
50
What is the effect of temperature on the rate of reaction between sodium thiosulfate and hydrochloric acid?
Increasing temperature generally increases the rate of reaction.
51
What equipment is needed to measure the dependent variable in the investigation?
D. timer
52
What equipment is needed to measure the independent variable in the investigation?
C. thermometer
53
What effect does increasing the temperature of a reaction have on its rate?
B. the rate increases because the frequency of collisions is increased
54
Fill in the blank: The student records the time it takes for the 'X' to be obscured by the _______.
yellow precipitate
55
What is the purpose of the piece of paper marked with an 'X' in the investigation?
To visually determine when the reaction has progressed to a certain point.
56
True or False: The conical flask is used to measure the independent variable.
False
57
Fill in the blank: The reactants mixed in the investigation are sodium thiosulfate and _______.
hydrochloric acid
58
What is the name of the piece of equipment labelled X?
B. gas syringe
59
What is a hypothesis?
C. an idea that can be tested
60
How does a catalyst increase the rate of a reaction?
It reduces the activation energy of the reaction
## Footnote
A catalyst provides an alternative reaction pathway with lower energy requirements.
61
What is the thermal decomposition reaction of hydrogen peroxide as shown in Equation 1?
2H2O2(l) → 2H2O(l) + O2(g)
## Footnote
This reaction involves breaking down hydrogen peroxide into water and oxygen.
62
In the investigation, how did the students measure the rate of reaction?
By recording the volume of oxygen gas produced after 30 seconds
## Footnote
The volume of gas produced is a common method to assess reaction rates.
63
Which substance in Table 1 is the most suitable catalyst for the reaction shown by Equation 1?
D
## Footnote
The results indicated that Substance D produced the highest volume of oxygen in the shortest time.
64
Fill in the blank: A catalyst _______ the activation energy of a reaction.
reduces
65
True or False: A catalyst changes the products of the reaction.
False
## Footnote
A catalyst does not alter the products but facilitates the reaction.
66
What volume of oxygen was produced in 30 seconds with Substance A?
11 cm3
67
What volume of oxygen was produced in 30 seconds with Substance D?
21 cm3
68
What color do copper objects change to over many years?
Dull, green-blue color
## Footnote
This color change is due to an oxidation reaction.
69
What is the cause of the change in appearance of copper objects?
Oxidation reaction
## Footnote
The oxidation reaction leads to the dulling of the copper's original shiny color.
70
Why does the oxidation reaction of copper take place over many years?
C. the reaction has a very high activation energy
## Footnote
High activation energy means that the reaction proceeds slowly over time.
71
How does the size of the particles in a solid affect its rate of reaction?
C. smaller particles have a greater surface area to volume ratio which increases the rate of reaction
## Footnote
A greater surface area allows for more collisions between reactant particles.
72
True or False: Larger particles have a greater surface area to volume ratio which increases the rate of reaction.
False
## Footnote
Larger particles have a smaller surface area to volume ratio.
73
Fill in the blank: The reaction that causes copper to change color is an _______.
oxidation reaction
## Footnote
This term refers to the chemical process that changes the state of the metal.
74
What happens to the surface area to volume ratio as particle size increases?
It decreases
## Footnote
A decrease in this ratio leads to a slower reaction rate.
75
What happens to reactants during a chemical reaction?
Reactants are used up.
76
How does the rate of reaction change as reactants are used up?
The rate of reaction decreases.
77
Explain, in terms of particles, why the rate of reaction decreases.
As reactants are used up, there are fewer particles available to collide and react.
78
What does the rate of reaction graph show?
The rate of reaction graph shows that the reaction goes quickly to start with and then starts to level off.
## Footnote
The leveling off indicates that there are more products and less reactants, leading to fewer reactions occurring.
79
Write down the formula to calculate the rate of reaction.
Rate of reaction = quantity of product formed / time taken
80
Calculate the rate of reaction when the amount of product made is 650g and it takes 50 seconds to produce.
Rate of reaction = 650g / 50s = 13g/s
81
What happens when a reaction is in equilibrium?
The rate of the forward reaction is equal to the rate of the reverse reaction.
82
Why does the rate of reaction graph level off?
The graph levels off because there are more products and less reactants, resulting in fewer reactions occurring.
83
What is the definition of a catalyst?
A catalyst speeds up the rate of a reaction without being used up.
84
How do catalysts work?
Catalysts lower the activation energy.
## Footnote
For example, they provide a surface area for the reactants to bind to.
85
Describe how increasing the surface area of a solid reactant affects the rate of reaction.
Increasing the surface area of a solid reactant makes the rate of reaction quicker.
86
Why does increasing the surface area of a solid reactant result in a quicker reaction?
There is more surface area for the reactants to react with, so the reaction occurs quicker.
87
What happens to particles when they are heated in terms of collision theory?
When particles are heated, they have more kinetic energy, collide more frequently with more energy, and there are more successful collisions.
88
When concentration increases, why does the rate of the reaction increase?
There are more particles in the same volume, so collisions are more frequent.
89
What is the first step in the reaction between marble chips and hydrochloric acid?
Measure out the HCl
## Footnote
Hydrochloric acid (HCl) is used to react with marble chips (calcium carbonate) to produce carbon dioxide.
90
What should be done after pouring hydrochloric acid into a conical flask?
Measure out the marble chips
## Footnote
Marble chips are the solid reactant in this experiment.
91
What is the purpose of adding a bung and delivery tube after adding marble chips to the flask?
To collect the gas produced
## Footnote
The delivery tube directs the carbon dioxide gas into a gas syringe for measurement.
92
How often should gas be measured during the reaction?
Every 10 seconds
## Footnote
This allows for tracking the rate of gas production over time.
93
What does a balance measure in the context of gas production?
The mass lost during the reaction
## Footnote
The mass loss correlates with the amount of gas produced.
94
Choose the correct statement regarding mass and reaction speed: The quicker the mass lost, the _______.
quicker the reaction
## Footnote
This indicates that a faster loss of mass correlates with a faster reaction rate.
95
What is the mean rate of reaction calculated from the produced gas volume and time?
Divide the amount of product formed by the time taken
## Footnote
This gives the average rate over the reaction period.
96
What was the volume of gas produced when the reaction finished?
80 cm³
## Footnote
This volume was recorded at the end of the reaction period.
97
Calculate the mean rate of reaction based on the provided data.
Mean rate = 80/70 = 1.14 cm³/s
## Footnote
This represents the average rate of gas production during the reaction.
98
What should be done to visualize the results of gas production over time?
Draw a graph with a curve of best fit
## Footnote
This helps to interpret the data trends effectively.
99
How would you sketch a graph to show a slow reaction?
Show a gradual increase in volume of gas over time
## Footnote
The graph should reflect a lower slope compared to that of a fast reaction.
100
What characterizes a sketch of a graph showing a quick reaction?
A steep increase in volume of gas over time
## Footnote
This indicates a rapid production of gas.
101
Why would you add a tangent to the graph?
To see how the reaction rate changes
## Footnote
A tangent can indicate the instantaneous rate at a specific point in time.
102
What does the steepness of the tangent on a graph indicate?
How fast the rate of reaction is
## Footnote
A steeper tangent indicates a faster reaction rate.
103
Find the mean rate of reaction between these points: At 30s, 20 cm³ of product; at 60s, 75 cm³ of product.
Mean rate = 55/30 = 1.8 cm³/s
## Footnote
This calculation shows the average rate of gas production over the specified time interval.
