Chapter 10 Reaction rates & equilibrium Flashcards

1
Q

What is the equation for rate of reaction, With concentration?

A

Rate of reaction = Change in concentration / Time

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2
Q

What are the four main factors that change rate of reaction?

A
  • Concentration
  • Temperature
  • Use of a catalyst
  • Surface area of solid reactants
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3
Q

What is the collision theory?

A

States that two reacting particles must collide for a reaction to occur

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4
Q

What two conditions must be met for a collision to be effective?

A
  • The particles collide with the correct orientation

- The particles have sufficient energy to overcome the activition energy barrier of the reaction

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5
Q

What are the effects of increasing concentration on rate of reaction?

A

An increase in concentration increases the number of particles in the same volume so the particles are closer together and have a higher freqency of collisions

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6
Q

What are the effects of increasing pressure on rate of reaction?

A

As pressure increases, the concentration of the gas molecules increases as the same number of gas molecules occupy a smaller volume. The gas molecules are closer together and collide more frequently leading to mroe effective collisions

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7
Q

What is a catalyst?

A

A substance that changes the rate of a chemical reaction without undergoing any permanent change itself

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8
Q

What is a homogeneous catalyst?

A

A catalyst in the same physical state as the reactants

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9
Q

How does a homogeneous catalyst work?

A

The catalyst reacts with the reactants to form an intermediate
The intermediate then breaks down to give the product
The catalyst is regenerated

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10
Q

What is a hetrogeneous catalyst?

A

A catalyst in a different physical state from the reactants

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11
Q

How does a hetrogeneous catalyst work?

A

Reactant molecules are adsorbed onto the surface of the catalyst where the reaction takes palce
After the reaction, the product molecules leave the surface of the catalyst by desoprtion

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12
Q

What are reversible reactions?

A

Reactions that take place in both ‘forward’ and ‘reverse’ directions

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13
Q

What is a closed system?

A

A system isolated from its surroudings, so the temperature,pressure and concentrations of reactants and products are unaffected by outside influences

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14
Q

What does the position of equilibrium indicate?

A

The extent of the reaction

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15
Q

What is Le Chatelier’s principle?

A

When a system in equilbrium is subjected to an external change the system readjusts itself to minimise the effect of that change

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16
Q

What are the effects of concentration changes on equilibrium?

A

An increase in concentration of reactants leads to a decrease in concentration of products and the position of equilbrium will shift to the right

An increase in concentration of products leads to a decrease in concentration of reactants and the position of equilibrium will shift to the left

17
Q

What are the effects of temperature change on equilbrium when the forward reaction is exothermic

A

Increase in temp, shifts position of equilibirum to the left

Decrease in temp, shifts position of equilibrium to the right

18
Q

What are the effects of temperature change on equilbrium when the forward reaction is endothermic

A

Increase in temp, shifts position of equilibirum to the right

Decrease in temp, shifts position of equilibrium to the left

19
Q

What are the effects of chaning pressure on equilibrium?

A

Increase in pressure shifts towards the fewer gaseous molecules
Decrease in pressure shifts towards the more gaseous molecules

20
Q

What are the effects of a catalyst on equilibrium?

A

Catalysts have no effect on equilbrium

21
Q

Regarding the boltzmann distribution, what does the curve starting at the origin suggest?

A

That no molecules have zero energy

22
Q

Regarding the boltzmann distribution, what does the area under the curve represent

A

The total number of molecules

23
Q

Regarding the boltzmann distribution, what does the curve not reaching the x-axis suggest?

A

That there is no maximum energy for a molecule

24
Q

What are the effects of temperature on a boltzmann distribution curve?

A

Shorter peak more to the right and fatter, larger area of activation energy

25
Q

What are the effects of a catalyst on a boltzmann distribution curve?

A

The activation line moves to the left

26
Q

Regarding the equilibrium constant what does the value of k tell us?

A

When k = 1, position of equilibrium is halfway between the products and reactants
When k > 1, position of equilibirum is towards the products
When k < 1, position of equilibrium is towards the reactants