C2.4 Rates of Reaction NOT FINISHED

Question 1

How does temperature affect the rate of a reaction?

Answer 1

The higher the temperature, the faster the reaction

Question 2

How does the concentration of reactants (or pressure for gases) affect the rate of a reaction?

Answer 2

The more concentrated the reactants (or pressure for gasses), the faster the reaction goes

Question 3

How does the surface area of reactants affect the rate of a reaction?

Answer 3

The larger the surface area, the faster the reaction goes

Question 4

How do catalysts affect the rate of a reaction?

Answer 4

Reactions with catalysts will go faster than those without

Question 5

What is collision theory?

Answer 5

The rate of a reaction depends on how often and how hard the reacting particles collide with each other

Question 6

How do particles react?

Answer 6

Particles have to collide hard enough and with enough energy in order to react

Question 7

What are the two ways rate of reaction can be increased?

Answer 7

By increasing the number of collision so that the probability of a successful collision increases, and/or increase the energy of the collisions so that more of the collisions are successful

Question 8

How does temperature affect the number of collision in a reaction?

Answer 8

An increase in temp. means that the particles all move quicker - if they’re moving quicker, they will collide more often and cause more successful collisions

Question 9

How does concentration affect the number of collision in a reaction?

Answer 9

A more concentrated solution, means there are more particles of reactant knocking between the water molecules, so there are more collisions between the important particles

Question 10

How does pressure (of a gas) affect the number of collision in a reaction?

Answer 10

Similar to concentration, the particles are forced closer together so there are more frequent collisions

Question 11

How does the surface area affect the number of collision in a reaction?

Answer 11

Breaking up a solid into smaller pieces will increase the total surface area, which means that there is more area for the particles to work on which results in more frequent collision and an increase in the rate of reaction

Question 12

How does temperature affect the energy of collisions in a reaction?

Answer 12

Particles require a certain amount of energy in order to react (this is called the activation energy), so increasing the temp. will provide the energy need for a reaction to take place

Question 13

What is a catalyst?

Answer 13

A substance which can speed up a reaction, without being changed or used up in the reaction

Question 14

Why are catalysts beneficial for industries? (3)

Answer 14

Because it allows them to produce the same amount of product in less time, it allows reactions to work at a lower temp. and they don’t get used up in the reaction so they can be used over and over again

Question 15

What are disadvantages of using catalysts? (4)

Answer 15

They can be expensive, they need to be removed from the product and cleaned which is inconvenient, different reactions use different catalysts so some plants may require several different catalysts, and catalysts can be ‘poisoned by impurities, so they stop working

Question 16

What is the formula for the rate of a reaction?

Answer 16

Rate of reaction = amount of reactant used or product formed / time

Question 17

What method can be used to measure the rate of reaction (which involves a precipitate)?

Answer 17

Observe a cross through a solution, add the reactant, measure how long it takes for the solution to go completely cloudy so you can’t see the cross - but this can be difficult to see exactly when the cross disappears

Question 18

What method can be used to measure the rate of reaction (which involves a change in mass)?

Answer 18

Used on a reaction which produces a gas, measure how long it takes to lose a certain amount of mass - this is very accurate due to the balance, but it releases gas into the room which could be harmful

Question 19

What method can be used to measure the rate of reaction (which involves the volume of gas produced)?

Answer 19

Using a gas syringe, see how much gas is produced in a set amount of time - gas syringes are quite precise, and this experiment prevents gas from being released into the room which is good

Question 20

How can we show the rate of a reaction?

Answer 20

On a graph - the amount of product formed (or amount of reactant used) in a reaction is plotted against time

Question 21

What is the common gradient of a rate of reaction graph? why?

Answer 21

It begins to react quickly, it the slowly begins to slow down and then it levels off (it’s stopped reacting) - this Is because to begin with, there are lots of particles so there are more collisions

Question 22

When comparing graphs, what does it mean if a rate of reaction graph has a steeper line to begin with?

Answer 22

It reaction is occurring at a faster rate - the sooner a reaction finishes means it is faster as well

Question 23

Where will two graphs with the same amount of reactant used finish?

Answer 23

At the same height - as they produce the same amount of product