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A Level - Chemistry > 10: Equilibrium I > Flashcards

10: Equilibrium I Flashcards

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1
Q

What is a reversible reaction?

A

Products break down into reactants

Mixture is present

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2
Q

What is an irreversible reaction?

A

All reactants turn into products

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3
Q

What is the formation of products called in equilibrium?

A

Forward reaction

“left to right”

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4
Q

What is the formation of the reactants called in equilibrium?

A

Backward reaction

“right to left”

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5
Q

What does dynamic equilibrium mean?

A

Dynamic - forward and backward reactions are constantly occurring, rates are equal
Equilibrium - no net change to amounts of reactant and product

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6
Q

What are all reversible reactions assumed to occur in?

A

A closed system

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7
Q

What is the term if more reactant is present at equilibrium?

A

Equilibrium lies to the left-hand side

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8
Q

What is the term if more product is present at equilibrium?

A

Equilibrium lies to the right-hand side

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9
Q

What is Le Chatelier’s principle?

A

When a change is applied to a system in dynamic equilibrium, the equilibrium shifts to oppose the change

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10
Q

What happens if the conc of the reactant is increased/ conc of product decreases?

A

Equilibrium shifts to the right

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11
Q

What happens if the conc of the reactant decreases / conc of product increases?

A

Equilibrium shifts to the left

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12
Q

How does increasing pressure affect a system in equilibrium ?

A

Equilibrium shifts to the side with fewer moles of gas

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13
Q

How does decreasing pressure affect a system in equilibrium ?

A

Equilibrium shifts to the side with most moles of gas

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14
Q

How is enthalpy related in reversible reactions?

A

Enthalpy value in forward reaction is equal and opposite to that of the backwards reaction
One is exothermic, the other endothermic

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15
Q

If the forward reaction is exothermic, what affect will increasing/decreasing the temperature have?

A

Increased - equilibrium shifts to the left

Decreased - equilibrium shifts to the right

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16
Q

If the forward reaction is endothermic, what affect will increasing/decreasing the temperature have?

A

Increased - equilibrium shifts to the right

Decreased - equilibrium shifts to the left

17
Q

What is the main reaction in the Haber process?

A

N2 + 3 H2 -> 2 NH3

All gas

18
Q

What is the enthalpy of the forward reaction of the Haber process?

A

-92 kJ/mol

19
Q

Where are the reactants found for the Haber process?

A

Hydrogen - natural gas

Nitrogen - atmosphere

20
Q

What are the conditions of the Haber process?

A 
Nitrogen to hydrogen in 1:3 ratio
~400 C
200 atm
Iron catalyst
Unreacted reactants are recycled
21
Q

What are the compromises of the conditions of the Haber process?

A

High yield of ammonia (shifts equilibrium)
Produces it quickly (decreases time to reach equilibrium)
Economic considerations

22
Q

What does the temperature (~400C) in the Haber process do?

A

Low temp - as forward reaction is exothermic
Increases rate of reaction
Compromise - reduces yield of ammonia but decreases production time

23
Q

What does the pressure (200 atm) in the Haber process do?

A

High pressure - favours forward reaction (more ammonia)

Compromise - not as high as possible as its expensive

24
Q

What does the catalyst (iron) in the Haber process do?

A

No affect on equilibrium

Increases rate of reaction

25
Q

What is a stoichiometric power?

A

Means number of molecules in the equation

Big number in front of molecule

26
Q

What is Kc?

A

Equilibrium constant
At a given temperature
Only gases, aqueous

27
Q

What is the Kc equation?

A

[C]^c x [D]^d
——————- = Kc
[A]^a x [B]^b

[A] [B} - product of conc of reactants
[C] [D] - product of conc of products
a b c d - number of molecules of each molecule

28
Q

What does a large Kc mean?

A

Higher conc of products than reactants at equilibrium

29
Q

What does a small Kc mean?

A

Higher conc of reactants than products at equilibrium

30
Q

What does a Kc value = 1 mean?

A

Roughly equal quantities of products and reactants at equilibrium

A Level - Chemistry (26 decks)

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