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Chemistry Unit 2 > Equlibrium > Flashcards

Equlibrium Flashcards

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1
Q

What is chemical equilibrium?

A

A state where the rate of the forward and reverse reactions occurs at the same rate

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2
Q

What indicates that a reaction goes to completion?

A

The entire limiting reagent has been used up, indicated by →

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3
Q

What is a reversible reaction?

A

A reaction that can proceed in both forward and reverse directions

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4
Q

Provide an example of a reversible reaction.

A

2502(g) + O2(g) ↔ 2503(l)

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5
Q

What does the symbol ↔ represent in a reversible reaction?

A

Equilibrium, indicating the reaction can occur in both directions

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6
Q

What is dynamic equilibrium?

A

A state where the concentrations of reactants and products remain constant with no observable change

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7
Q

What is meant by ‘the position of the equilibrium’?

A

The extent to which the reaction has gone towards the products

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8
Q

What are fixed conditions in a chemical equilibrium?

A

Temperature and pressure remain the same

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9
Q

What defines an isolated system in chemical equilibrium?

A

No material is added or removed from the system

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10
Q

True or False: At equilibrium, the concentrations of reactants and products change over time.

A

False

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11
Q

Fill in the blank: A reversible reaction can take place in the ______ direction.

A

[forward and reverse]

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12
Q

What is equilibrium in the context of a chemical reaction?

A

Equilibrium is the state when the rate of forward reaction equals the rate of reverse reaction.

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13
Q

What does the graph of the formation of ammonia from hydrogen and nitrogen gases depict?

A

The graph depicts the disappearance of reactants (H and N) and the appearance of products (NH3) over time.

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14
Q

What does it mean when the lines in the concentration graph level off?

A

It indicates that constant concentration has been achieved, meaning equilibrium is reached.

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15
Q

In the reaction N2(g) + 3H2(g) = 2NH3(g), what happens from points A to B?

A

The reaction is occurring and products are being made.

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16
Q

What occurs between points B and C in the concentration graph?

A

Equilibrium exists, but the forward and reverse reactions are still occurring.

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17
Q

True or False: At equilibrium, the concentrations of reactants and products change.

A

False

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18
Q

Fill in the blank: At equilibrium, the concentrations of reactants and products are _______.

A

stable

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19
Q

What are the components of the reaction that forms ammonia?

A
  • N2(g)
  • 3H2(g)
  • 2NH3(g)
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20
Q

What does the term ‘constant concentration’ refer to?

A

It refers to the state achieved when the concentrations of reactants and products remain unchanged.

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21
Q

What factors can alter the position of equilibrium?

A

1) Changing the concentration of reactants or products
2) Changing the pressure (if gases involved)
3) Changing temperature

These factors can shift the equilibrium position.

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22
Q

What principle can be used to predict the effects of changes on equilibrium?

A

Le Chatelier’s Principle

This principle states that a system at equilibrium will shift to counteract changes imposed upon it.

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23
Q

According to Le Chatelier’s Principle, how does a system in equilibrium respond to a change?

A

The equilibrium will shift to counteract the change.

This means it will oppose the change imposed upon it.

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24
Q

What happens to the equilibrium when the concentration of reactants is increased?

A

The equilibrium shifts towards the products.

This occurs to remove the extra reactants by shifting the equilibrium in the forward direction.

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25
What is the effect of increasing the concentration of products on equilibrium?
The equilibrium shifts towards the reactants. ## Footnote This happens to remove the extra products by shifting the equilibrium in the reverse direction.
26
In the reaction Co(H2O)2* + 4Cl (a) = CoCl4 (a) + 6H2O (aq), what color change occurs when HCl is added?
The color changes from pink to blue. ## Footnote This is due to the increase in the concentration of Cl ions which shifts the equilibrium towards the products.
27
What happens to the reaction when H2O molecules are added to the mixture after HCl?
The color changes from blue to pink. ## Footnote This occurs because the concentration of Cl ions decreases, shifting the equilibrium towards the reactants.
28
Fill in the blank: Le Chatelier's Principle states that if a system at equilibrium is subjected to a change, the equilibrium will shift to _______.
counteract the change. ## Footnote This principle helps predict how equilibrium systems will respond to different stresses.
29
What happens to the equilibrium when pressure is increased in a system with gases?
The equilibrium moves to the side with the least number of moles of gas ## Footnote This is observed through an initial darkening followed by lightening of the brown NO color.
30
What is the effect of decreasing pressure on the equilibrium of gases?
The equilibrium moves to the side with the most number of moles of gas ## Footnote This is indicated by an initial lightening followed by darkening of the brown NO color.
31
What color is associated with the gas NO in the syringe?
Brown ## Footnote NO is the brown gas in the equilibrium system.
32
What color is associated with the gas N2O in the syringe?
Colourless ## Footnote N2O does not contribute to the color change observed in the system.
33
If the pressure is increased, what initial visual change is observed in the syringe?
Darkening of the brown NO color ## Footnote This occurs due to the concentration of gases increasing.
34
If the pressure is decreased, what initial visual change is observed in the syringe?
Lightening of the brown NO color ## Footnote This occurs due to the dilution of gases.
35
What is the relationship between pressure changes and the number of moles of gas in the system?
Increasing pressure favors the side with fewer moles and decreasing pressure favors the side with more moles ## Footnote This relationship is based on Le Chatelier's principle.
36
Fill in the blank: Increasing pressure moves the equilibrium towards the side with _______ moles of gas.
the least number of
37
Fill in the blank: Decreasing pressure moves the equilibrium towards the side with _______ moles of gas.
the most number of
38
What is the total number of moles of gas present in the syringe?
3 moles ## Footnote 1 mole of N2O and 2 moles of NO are present.
39
What effect does a change in temperature have on equilibrium?
A change in temperature affects the position of the equilibrium.
40
What type of reaction is represented by NH, Co) - Hate) + HCg)?
Endothermic reaction.
41
What happens to the equilibrium when the reaction is heated?
It moves to the products.
42
What side of the reaction is considered endothermic?
The cold side.
43
What occurs when the reaction is cooled?
The reaction moves to the reactants.
44
What side of the reaction is considered exothermic?
The hot side.
45
What principle explains how equilibrium responds to changes?
The equilibrium moves to oppose the change imposed upon it.
46
What happens to the equilibrium when the temperature is increased?
The equilibrium will move to the side that will reduce temperature.
47
What happens to the equilibrium when the temperature is decreased?
The equilibrium will move to the side that will increase temperature.
48
What is the effect of a catalyst on the position of equilibrium?
A catalyst has no effect on the position of the equilibrium.
49
How does a catalyst affect the rate of a reaction?
A catalyst speeds up the rate of a reaction.
50
True or False: A catalyst changes the position of equilibrium.
False
51
True or False: A catalyst increases the rate at which equilibrium is achieved.
True
52
Fill in the blank: A catalyst only increases the rate at which _______ is achieved.
equilibrium
53
What is true for both the forward and reverse reaction regarding catalysts?
A catalyst speeds up the rate at which equilibrium is achieved.
54
What is the equilibrium constant denoted as?
K
55
What is a homogeneous equilibrium?
An equilibrium where everything is present in the same phase
56
What are usual examples of homogeneous equilibrium?
* Reactions where everything is a gas * Reactions where everything is in the same solution
57
In the general equilibrium expression for the reaction aA + bB ⇌ cC + dD, how are the concentrations represented?
K = [C]^c [D]^d / [A]^a [B]^b
58
What does the symbol [ ] represent in the equilibrium constant expression?
Concentrations in mol cm^-3
59
What is the relationship between the equilibrium constant and temperature?
The equilibrium constant always has the same value provided you don't change the temperature
60
Is the equilibrium constant affected by changes in pressure?
No, it is unaffected by a change in pressure
61
What role does a catalyst play in relation to the equilibrium constant?
It does not affect the equilibrium constant
62
In the K expression, how are the substances in the chemical equation organized?
Substances on the right-hand side are on top; left-hand side on the bottom
63
Fill in the blank: The indices in the equilibrium constant expression are the numbers in front of each _______.
[substance] in the chemical equation
64
True or False: The equilibrium constant can change based on the amounts of reactants and products used.
False
65
What does the magnitude of Kc indicate about a reaction?
It indicates the position of an equilibrium reaction and how far a reaction proceeds, not how fast it occurs.
66
What does Kc = 1 signify?
The reaction lies in-between the reactants and products, with the rate of the forward reaction equal to the rate of the reverse reaction.
67
When Kc > 1 (e.g., Kc = 10), what does this indicate?
The reaction lies in the forward direction, favoring product formation.
68
What does Kc >> 1 (e.g., Kc = 1 × 10^59) suggest about the reaction?
The reaction lies heavily in the forward direction, containing almost all products and nearly going to completion.
69
What does Kc < 1 indicate about a reaction?
The reaction lies in the reverse direction, favoring reactant formation.
70
What does Kc << 1 (e.g., Kc = 1 x 10^-17) imply about the reaction?
The reaction lies heavily in the reverse direction, containing almost all reactants and hardly proceeding at all.
71
72
What process is used for the production of ammonia in industry?
Haber-Bosch process ## Footnote The Haber-Bosch process involves the reaction of nitrogen and hydrogen in the presence of a catalyst.
73
What are the reactants in the Haber-Bosch process for ammonia production?
Nitrogen (N2) and Hydrogen (H2) ## Footnote The reaction is N2(g) + 3H2(g) → 2NH3(g).
74
What is the role of the granulated iron catalyst in the Haber-Bosch process?
To increase the rate at which equilibrium is established ## Footnote This helps produce ammonia more quickly.
75
What temperature is typically used in the Haber-Bosch process?
450 °C ## Footnote This temperature is chosen to maximize ammonia production.
76
How does removing ammonia from the reaction mixture affect the equilibrium position?
It shifts the position of equilibrium further to the right ## Footnote This results in the production of more ammonia.
77
What effect does increasing pressure have on the yield of ammonia?
The yield of ammonia increases ## Footnote Higher pressure shifts the equilibrium to the right, reducing the number of molecules.
78
At what pressure is the Haber-Bosch process typically operated for maximum profit?
250 atmospheres ## Footnote This pressure represents a compromise between yield and cost.
79
True or False: Higher temperatures always increase the yield of ammonia.
False ## Footnote Higher temperatures may increase the rate but can lower the yield.
80
Fill in the blank: The reaction for ammonia production can be represented as N2(g) + 3H2(g) → _______.
2NH3(g) ## Footnote This equation shows the stoichiometry of the reaction.
81
What is the enthalpy change (ΔH) for the ammonia production reaction?
-92 kJ ## Footnote This indicates that the reaction is exothermic.
82
What is the relationship between pressure and equilibrium position in the Haber-Bosch process?
Higher pressure shifts the equilibrium to the right ## Footnote This reduces the number of gas molecules in the reaction.
83
What happens to the profitability of the Haber-Bosch process at very high pressures?
Increased costs of equipment reduce profits ## Footnote This makes it necessary to find a balance in operating pressure.
84
What happens to the yield of ammonia as the reaction temperature increases?
The yield of ammonia decreases as the temperature of the reaction mixture is increased. ## Footnote This is due to the exothermic nature of the forward reaction and Le Chatelier's Principle.
85
What is the operating temperature chosen for ammonia production?
450 °C. ## Footnote This temperature represents a compromise between reaction rate and yield.
86
What principle explains the shift in equilibrium with temperature changes?
Le Chatelier's Principle. ## Footnote It states that the position of equilibrium shifts to absorb changes in heat.
87
What is the primary use of sulfuric acid?
To make a wide range of useful materials including fertiliser, paints, detergents, and pharmaceuticals. ## Footnote Sulfuric acid is a key industrial chemical.
88
What is the name of the process used to produce sulfuric acid?
The Contact process. ## Footnote This process involves multiple steps including the production of sulfur dioxide.
89
What is the first step in the Contact process for sulfuric acid production?
S (s) + O2(g) → SO2(g). ## Footnote This step involves burning sulfur in air to produce sulfur dioxide.
90
At what temperature is sulfur dioxide mixed with air in the Contact process?
450 °C. ## Footnote This temperature is crucial for the subsequent reactions.
91
What catalyst is used in the reaction of sulfur dioxide with oxygen?
Vanadium (V) oxide, V2O5. ## Footnote This catalyst facilitates the formation of sulfur trioxide.
92
What is the reaction equation for the formation of sulfur trioxide from sulfur dioxide?
2SO2(g) + O2(g) → 2SO3(g) ΔH = -197 kJ. ## Footnote This reaction is exothermic and establishes chemical equilibrium.
93
How does increasing temperature affect the yield of sulfur trioxide?
It decreases the yield of sulfur trioxide as the equilibrium shifts to the left. ## Footnote This shift occurs in an effort to absorb excess heat.
94
What is the compromise temperature for sulfur trioxide production?
450 °C. ## Footnote This temperature balances the need for a reasonable yield and a sufficient reaction rate.
95
How does increasing the operating pressure affect the yield of sulfur trioxide?
It is expected to further increase the yield of sulfur trioxide at equilibrium. ## Footnote However, the cost of high pressure may not be justified.
96
What is the final step in the production of sulfuric acid?
Dissolving sulfur trioxide in sulfuric acid and adding water. ## Footnote This step produces oleum.

Chemistry Unit 2 (11 decks)

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