C2 - Rates of Reaction

Question 0

Where are catalysts used?

Answer 0

They are used in industrial chemical reactions where there isn’t much time
They are used in catalytic converters

Question 1

What is a catalyst?

Answer 1

A substance that massively increases the rate of a reaction without being used up or changed

Question 2

What are the 4 factors that can change the speed of a reaction?

Answer 2

Temperature, concentration, surface area and pressure

Question 3

Why is a catalytic converter needed?

Answer 3

The harmful gases of carbon monoxide and nitrogen oxides are changed to the much less harmful carbon dioxide and nitrogen

Question 4

What is the biggest problem with catalysts?

Answer 4

They are very specific

Only one type of catalyst will catalyse a specific reaction

Question 5

What is the Haber process?

Answer 5

Iron is used as a catalyst to produce ammonia from nitrogen gas and hydrogen gas

Question 6

How do catalysts work?

Answer 6

The catalyst particles collide with the reactant particles and lower the activation energy by providing an alternative route for the reaction

Question 7

What is concentration?

Answer 7

It is the amount of molecules of the reactant dissolved in a given volume of water

Question 8

How does concentration change the rate of reaction?

Answer 8

If the particles are more crowded (higher concentration) they are much more likely to collide so the reaction is faster

Question 9

How does pressure affect the rate of reaction?

Answer 9

If we squash more gas into a smaller area, the molecules will be closer together meaning they are more likely to collide

Question 10

What is pressure?

Answer 10

How much gas has been squashed into a given area

They have more pressure making the particles closer together

Question 11

How does temperature affect the rate of reaction?

Answer 11

If there is a higher temperature, the particles will vibrate more giving them more energy
More energy means they move faster and are more likely to collide

Question 12

How does surface area affect the rate of reaction?

Answer 12

If the surface area is larger, more of the reactant is exposed meaning the particles of the other reactant are more likely to collide with it

Question 13

Give 2 ways in which we can measure the rate of a reaction

Answer 13

How fast the reactants are used up

How fast the products of the reaction are formed

Question 14

What is collision theory?

Answer 14

The theory that substances react when the particles of the reactants collide, break apart and then re-form to create new substances

Question 15

What are successful collisions?

Answer 15

Collisions that result in a chemical reaction

Question 16

What is activation energy?

Answer 16

The amount of energy that needs to be put in to trigger the reaction

Question 17

What are the 3 ways of measuring the rate of reaction?

Answer 17

Change in mass

Volume of gas given off

Precipitation

Question 18

How do you measure rate of reaction with precipitation?

Answer 18

This is when the product of the reaction is a precipitate that clouds the solution

Observe a mark through the solution and measure how long it takes to disappear

The quicker the mark, the quicker the tst

Question 19

What are the 2 problems with the precipitation rate of reaction experiment?

Answer 19

Different people might not agree on the exact point that the mark disappears

Only works for reactions where the initial solution is clear

Question 20

How do you measure rate of reaction using change in mass?

Answer 20

If a reaction produces a gas, you can measure the rate of reaction by looking at the change in mass (gas is lost)

You measure the change in mass by using a balance and looking at how fast the mass goes down

Question 21

What is the advantage and disadvantage of the change in mass experiment?

Answer 21

Very accurate because the mass balance is accurate

But the gas is released straight into the room

Question 22

How do you measure the rate of reaction with the volume of gas given off?

Answer 22

You use a gas syringe to collect up the gas of the reaction

The more gas given off in a given time, the faster the reaction

Question 23

What is the advantage and disadvantage of the volume of gas given off experiment?

Answer 23

The volume of gas measured is very accurate

If the reaction is too violent, you can blow the plunger out of the end of the syringe

Question 24

Describe the experiment you use to see the effect of surface area on rate of reaction

Answer 24

You put marble chips and hydrochloric acid in conical flask and use the volume of gas given off method to calculate the rate of reaction

You then do the same but crunch up the chips more which gives a larger surface area

The second reaction should happen faster

Question 25

Describe the experiment you use to see the effect of concentration on rate of reaction

Answer 25

You use the change in mass method to calculate the rate of reaction of magnesium metal and dilute hydrochloric acid

You do the sane reaction with a higher concentration hydrochloric acid

The second reaction should have a higher rate

Question 26

Describe the experiment you use to see the effect of temperature on rate of reaction

Answer 26

Let the 2 clear solutions of sodium thiosulphate and hydrochloric acid react in a comical flask and use the precipitation method to calculate the rate of reaction

Then use a water bath to heat the solutions up before mixing them and calculate the rate of reaction

The second reaction should be faster

Question 27

Describe the experiment you use to see the effect of a catalyst on rate of reaction

Answer 27

You put hydrogen peroxide in a conical flask and put in a catalyst

Use the volume of gas given off (oxygen gas) to calculate the rate of reaction

Do this method for all the different catalysts to be tested

Question 28

What are the 2 advantages of using catalysts in industrial reactions?

Answer 28

Increases rate of reaction so the plant doesn’t need to operate for as long saving money

Allows the reaction to work at lower temperatures and pressures

Question 29

What are the 3 disadvantages of using catalysts in industrial reactions?

Answer 29

They often need to be removed from the product and cleaned

Different reactions use different catalysts so they can be quite expensive

Catalysts can stop working because of impurities so you need to keep your reaction mixture very clean