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A-Level Chemistry > Equilibria > Flashcards

Equilibria Flashcards

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1
Q

What are the conditions for equilibrium?

A

closed system

concentrations of the reactants and products are constant

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2
Q

What is a dynamic equilibrium?

A

The forward and backward reactions are occurring simultaneously at a constant rate.

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3
Q

State Le Chatelier’s principle

A

If a factor affecting the position of equilibrium is altered, the position of equilibrium will shift to oppose the change.

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4
Q

What happens in a reversible reaction at equilibrium?

A

the forward and reverse reactions proceed at equal rates

the concentrations of reactants and products remain constant

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5
Q

Which are the three factors that affect equilibrium?

A

Pressure
Temperature
Concentration

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6
Q

What is a homogeneous equilibrium?

A

A reaction where every species is in the same physical state

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7
Q

What would be the effect of increasing the concentration of a reactant on the equilibrium?

A

The equilibrium will shift to the right to oppose the change

Therefore, more products will be produced

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8
Q

What woulld be the effect of increasing the concentration of a product on the equilibrium?

A

The equilibrium will shift to the left to oppose the change

Therefore, the reverse reaction will go faster

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9
Q

What would be the effect of increasing pressure on the equilibrium?

A

The equilibrium will shift to the side with fewer gas molecules
Therefore, reducing pressure

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10
Q

What is only affected by the change in pressure?

A

Gases

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11
Q

What would be the effect of increasing temperature on the equilibrium?

A

The equilibrium will shift in the endothermic direction

Therefore, the temperature will be decreased

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12
Q

What would be the effect of decreasing temperature ont the equilibrium?

A

The equilibrium will shift in the exothermic direction

Therefore, the temperature will be increased?

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13
Q

What does NOT affect the equilibrium position?

A

Catalysts

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14
Q

Why do catalysts not affect the position of equilibrium and yield?

A

They allow equilibrium to be reached faster

They speed up both forward and backward reactions at the same rate, therefore having no effect on the yield

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15
Q

Why are catalysts used in industry?

A

They allow lower temperatures to be used as they provide alternative routes with lower activation energie
Therefore, there are lower energy costs

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16
Q

What is the Haber process?

A

The manufacturing of ammonia

N2(g) + 3H2(g) ↔ 2NH3(g)

17
Q

What are the conditions for the Haber Process?

A

400-450 C
200-1000 atm
Iron catalyst

18
Q

Why are compromised conditions used in industry?

A

Low temperatures produce very high yields but the reactions are slow
High pressures also produce high yields but the equipment required is very expensive

19
Q

What is the Contact Process?

A

Stage 1: S(s) + O2(g) → SO2(g)

Stage 2: SO2(g) + 0.5O2(g) ↔ SO3(g)

20
Q

What are the conditions for the Contact Process?

A

450C
1/2 atm
V2O5 catalyst

21
Q

What are the conditions for the hydration of ethene to produce ethanol?

A

300C
70atm
conc. H3PO4

22
Q

What is the equation for the hydration of ethene?

A

C2H4(g) + H2O(g) ↔ C2H5OH(g)

23
Q

What do manufacturers do to improve the overall yields of processes?

A

They recycle uncreated reactants back into the reactors

24
Q

When calculating Kc, how is concentration of a species represented?

A

[ ] = equilibrium concentration

25
Q

How is Kc calculated?

A

Kc= [products] / [reactants]

26
Q

What are the units for concentration?

A

mol dm^-3

27
Q

How does temperature affect the Kc value?

A

When the temperature is altered, the Kc value and position of equilibrium will change

28
Q

How does pressure affect the Kc value?

A

The position of equilibrium will change but the Kc value remains constant

29
Q

How does a catalyst affect the Kc value?

A

A catalyst has no effect on the Kc value or the position of equilibrium

30
Q

What happens when Kc< 1?

A

Equilibrium shifts to the left

31
Q

What happens when Kc = 1?

A

Neither side of the system is favoured

32
Q

What happens when Kc> 1?

A

Equilibrium shifts to the right

33
Q

What is a homogeneous equilibrium?

A

Every species involved in the reaction is in the same phase

34
Q

What is a heterogeneous equilibrium?

A

There are different phases in the equilibrium mixture

35
Q

What is a phase?

A

A state of matter

36
Q

Give an example of a homogenous equilibrium

A

The Contact Process

37
Q

Give an example of a heterogeneous equilibrium?

A

The Haber Process

38
Q

Why are solids and liquids not included in the Kc expression in a heterogeneous equilibrium?

A

Liquids and solids are incompressible

Therefore, their concentrations are constant

A-Level Chemistry (30 decks)

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