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AQA Chemistry [Paper 2] > [Part 4]- C8- the rate and extent of chemical change 💥 > Flashcards

[Part 4]- C8- the rate and extent of chemical change 💥 Flashcards

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1
Q

RECAP: What is equilibrium ?

Hint: occur at the same…

A
  • [chemical] equilibrium, is a state in a reaction where the rate of the forward reaction, is equal to the rate of the reverse reaction.
  • [meaning, the forward and reverse reaction occur at the same rate]
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2
Q

What’s Le Chatelier’s principle ?

A
  • Le Chatelier’s principle states: when a system is at equilibrium, and a change is made to the conditions, the system [reaction] responds to counteract the changes.
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3
Q

What happens, if the reactant concentration increases ?

A
  • when the reactant concentration increases, more products will be formed.
  • this is because, of Le Chatelier’s principle therefore, it will counteract the change, by decreasing the concentration of the reactant.
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4
Q

How can a system, decrease the concentration of a reactant ?

Hint: favouring

Hint #2: rate at which…

A
  • a system, can decrease the concentration of a reactant by:
  • increasing the rate at which the reactant is used up, and favouring the forward reaction.
  • this increases the rate of formation of the product- until equilibrium is established again
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5
Q

What happens, if the product concentration increases ?

A
  • if the product concentration increases, more reactants will be formed.
  • this is because, of Le Chatelier’s principle therefore, the system will counteract the change by decreasing the concentration of the product.
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6
Q

How can a system, decrease the concentration of a product ?

Hint: until equilibrium

A
  • a system can decrease the concentration of a product by:
  • increasing the rate at which the product turns into reactants, and favouring the reverse reaction, increasing its rate- until equilibrium is established again
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7
Q

What’s the difference between equilibrium 🆚dynamic equilibrium ?

Hint: occuring

A
  • dynamic equilibrium is when the forward and reverse reactions are still occurring; the substances remain in balance [equilibrium].
  • and [chemical] equilibrium, is a state in a reaction where the rate of the forward reaction, is equal to the rate of the reverse reaction.
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8
Q

RECAP: What happens if a reversible reaction, is exothermic is one direction ?

A
  • if a reversible reaction is exothermic in one direction, the reversible reaction is then endothermic in the opposite direction.
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9
Q

What happens to the temperature, if the forward reaction is exothermic ?

Hint: why ?

A
  • as the forward reaction is exothermic:
  • when the forward reaction takes place, energy is released and the temperature of the system increases.
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10
Q
  • Fill in the gaps: Because every reversible reaction is _________, some reversible reactions are exothermic in the forwards direction.
  • ; some are endothermic in the _________ reaction.
A
  • Because every reversible reaction is different, some reversible reactions are exothermic in the forwards direction.
  • ; some are endothermic in the backwards reaction.
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11
Q

What happens to the temperature, if the backwards reaction is endothermic ?

A
  • if the backwards reaction is endothermic, energy is taken in and the temperature of the system decreases [when the reverse reaction takes place]
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12
Q

What is pressure ?

A
  • pressure, is the force exerted over an area.
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13
Q
  • Fill in the gaps: pressure, affects reactions involving _____
A
  • pressure, affects reactions involving gases
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14
Q

What does the pressure of a gas, depend on ?

A
  • the pressure of a gas depends on the number of molecules
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15
Q

What happens, if we increase the pressure on a reversible reaction, at equilibrium ? [2]

Hint: why ?

A
  • if we increase the pressure on a reversible reaction, at equilibrium:
  • the position of equilibrium shifts to the side with the smaller number of molecules.
  • this is because an increase in pressure, favours the side with less molecules.
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16
Q

What happens, if we reduce the pressure on a reversible reaction, at equilibrium ?

A
  • if we reduce the pressure on a reversible reaction, at equilibrium:
  • the position of equilibrium, shifts to the side with the larger number of molecules.
17
Q

What happens, if the number of molecules is the same on both sides?

Hint: pressure

A
  • if the number of molecules is the same on both sides, changing pressure, will have no effect on the position of equilibrium
18
Q

Regarding pressure, what happens if the forwards reaction produces more molecules of gas ?

Hint: yield

A
  • if the forwards reaction produces more molecules of gas:
  • an increase in pressure will decrease the yield of products formed
  • ; a decrease in pressure, will increase the yield of product formed
19
Q

Regarding pressure, what happens if the forwards reaction produces fewer molecules of gas ?

A
  • if the forwards reaction produces fewer molecules of gas:
  • an increase in pressure, will increase the yield of product formed
  • ; a decrease in pressure, will decrease the yield of product formed
20
Q

Regarding temperature, what happens if the forward reaction is exothermic ?

Hint: increase and decrease

A
  • if the forward reaction is exothermic:
  • an increase in temperature, decreases the yield of product formed
  • ; a decrease in pressure, increases the yield of products formed
21
Q

Regarding temperature, what happens if the forward reaction is endothermic ?

A
  • if the forward reaction is endothermic:
  • an increase in temperature increases the yield of product formed; a decrease in pressure, decreases the yield of product formed
22
Q

What happens if the temperature increases, to a system at equilibrium ?

A
  • if the temperature increases, the position of equilibrium will shift to reduce the temperature.
  • this is because of le chatelier’s principle therefore, the endothermic reaction will be favoured
23
Q

What happens if the temperature decreases, to a system at equilibrium ?

A
  • if the temperature decreases, equilibrium will shift to increase the temperature.
  • this is because of le chatelier’s principle so, the exothermic reaction will be favoured

AQA Chemistry [Paper 2] (17 decks)

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