Increasing the reaction rate

Question 1

How can the reaction rate be increased?

Answer 1

Increase the proportion of successful collisions

Question 2

how can the proportion of successful collisions be increased?

Answer 2

increasing frequency of collisions, or increasing the proportion of collisions that have sufficient energy to voercome the activation energy barrier.

Question 3

3 ways of increasing frequency of collisions?

Answer 3

increase concentration (solution), pressure (gas) or surface area

Question 4

how does increasing concentration of solution increase the rate of reaction?

Answer 4

as the concentration increases, there are more reactant particles moving randomly in a given volume. This increases the frequency of collisions, and hence the proportion of successful collisions – resulting in an increased reaction rate

Question 5

how does increasing the pressure of a gas increase the concentration?

Answer 5

as the pressure increases, the concentration increases…

Question 6

in terms of surface areas, what particles can react?

Answer 6

only those at the surface

Question 7

how can we increase the surface area?

Answer 7

break an object into smaller parts/make the object porous

Question 8

what is the effect of increasing sa on rate of reaction?

Answer 8

As the SA increases, more particles are exposed and can therefore collide with other reactants. This increases the frequency of collisions, and hence the proportion of successful collisions – resulting in an increased reaction rate.

Question 9

What does the maxwell-boltzmann distribution show?

Answer 9

at a given temperature: the number of particles with a particular kinetic energy

Question 10

in terms of the maxwell-boltzmann distribution, at a specific temperautre:

Answer 10

, most particles have a similar kinetic energy, but some have much more/less than others.

Question 11

area under the mb distribution?

Answer 11

equals total number of particles - the same for all.

Question 12

how can we increase the energy of collisions?

Answer 12

increase temperature, or add a catalyst

Question 13

how does temp increase the energy of collisions?

Answer 13

as temperature increases, the average kinetic energy of particles increases. Hence, collisions occur at greater energy and this energy is more likely to be greater than or equal to the activation energy. Hence the proportion of successful collisions will increase, and so will the reaction rate.

Question 14

does increasing temp increase the frequency of collisions?

Answer 14

yes - but to a SMALLER EXTENT. Increased temp  increased average kinetic energy of particles  higher frequency of collisions  higher proportion of successful reactions  higher rate of reaction.

Question 15

for maxwell-boltzmann distribution, what happens when temp is increased?

Answer 15

shifted to the right - increased average kinetic energy

Question 16

Characteristics of catalysts?

Answer 16

aren’t consumed.
Provide an alternative reaction pathway, resulting in lowered activation energy.
can be organic or inorganic.

Question 17

for maxwell boltzmann distribution, what happens when a catalyst is added?

Answer 17

you tell me

Question 18

mode of action for solid inorganic catalysts?

Answer 18

the reactants adsorb (form bonds with) it, which causes bonds between reactants to break, which allows new bonds between products to form.

Question 19

define: homogeneous catalyst

Answer 19

in the same physical state as the reactants and products

Question 20

define: hetergeneous catalysts

Answer 20

in a different physical state as the reactants and products.

Question 21

why are heterogeneous catalysts preferred by the chemical industry?

Answer 21

a) easier to separate from the products of a reaction and hence easier to reuse, and b) can be used at high temperature