Rates of Reaction- Chemistry Paper 2

Question 1

What is the rate of reaction?

Answer 1

How quickly the reactants are changed into products

Question 2

Is the rusting of iron a fast or a slow reaction?

Answer 2

Slow

Question 3

What are the 4 main factors that affect how quickly a reaction goes?

Answer 3

Temperature, concentration, surface area, catalysts

Question 4

What 2 things are collision theory dependent on?

Answer 4

• The frequency of reacting particles, or how often they collide
• The energy transferred during a collision, as particles have to collide with enough energy to be successful

Question 5

The more particle collisions…

Answer 5

the faster the reaction is

Question 6

What happens when the temperature is increased?

Answer 6

All particles gain more kinetic energy and so move quicker. Collisions will therefore occur more often , resulting in a faster rate of reaction

Question 7

What does increasing the concentration do?

Answer 7

Allow for more frequent collisions and therefore more collisions

Question 8

What is the concentration?

Answer 8

The particles per unit volume

Question 9

If one of the reactants is a solid, what will breaking it up into smaller pieces do?

Answer 9

Increase the surface to volume ratio

Question 10

Why does increasing the surface area to volume ratio result in more frequent collisions?

Answer 10

Because for the same volume particles will have more surface area to work on. This will result in more frequent collisions and so the rate of reaction will be faster.

Question 11

What does increasing the temperature also increase?

Answer 11

The energy of the collisions and the frequency of the collisions

Question 12

What is activation energy?

Answer 12

The minimum energy needed for the particles to react

Question 13

For a collision to be successful, what must happen?

Answer 13

The energy of the particles must be greater than or equal to the activation energy.

Question 14

What happens if particles don’t have enough energy to react?

Answer 14

Then the particles will simply just bounce off each other

Question 15

What is the rate of a reaction directly proportional to?

Answer 15

The frequency of successful collisions

Question 16

What can decrease the activation energy needed for a reaction to occur?

Answer 16

Catalysts

Question 17

What is the mean rate in reaction equal to?

Answer 17

The quantity of reactant used or product formed/time

Question 18

What is a reversible reaction?

Answer 18

A reaction where the products can react to become the original reactants

Question 19

What is a dynamic equilibrium?

Answer 19

where the rate of the forwards reaction is equal to the rate of the backwards reaction,

Question 20

Dynamic equilibrium must happen in what type of system?

Answer 20

A closed system, where none of the reactants or products can leave and nothing else can get in

Question 21

What is Le Chanelier’s principle?

Answer 21

The idea that if you change the conditions of a dynamic equilibrium reaction, the system will try to counteract the change.

Question 22

What happens if you raise the temperature of a reaction? (le chantelier’s)

Answer 22

The yield of the endothermic reaction will increase and the yield of the exothermic reaction will decrease.

Question 23

What happens if you decrease the temperature of a reaction? le chantelier

Answer 23

The yield of the exothermic reaction will increase and the yield of the endothermic reaction will decrease

Question 24

What happens if you increase the pressure of a reaction?(le chantelier)

Answer 24

the pressure will favour the side with fewer molecules to try and decrease the pressure

Question 25

What happens if you decrease the pressure of a reaction?

Answer 25

the pressure will favour the side with the greatest number of molecules

Question 26

What is the equation for the mean rate of reaction if the quantity of a reactant is measured?

Answer 26

mean rate of reaction = quantity of reactant used/ time taken

Question 27

What is the equation for the mean rate of reaction if the quantity of a product is measured?

Answer 27

quantity of product formed/ time taken

Question 28

Increasing the pressure...

Answer 28

increases the frequency of collisions and hence, increases the rate of reaction

Question 30

How can the change in a volume be measured?

Answer 30

The volume of a gas is measured using a gas syringe, or an upside down burette or measuring cylinder.

Question 31

What is the gradient of a line equal to?

Answer 31

The rate of reaction

Question 32

What is an example of a reversible reaction?

Answer 32

The production of ammonia

Question 33

What is the Haber process?

Answer 33

when nitrogen gas is reacted with hydrogen gas to make ammonia gas. The forward reaction is exothermic.

Question 34

What experiment could be used to see how changes in concentration affect the rates of reaction?

Answer 34

1) First, 50 cm^3 of sodium thiosulfate solution should be be measured in a measuring cylinder and then transferred into a flask. 2) With a separate measuring cylinder, 10cm^3 of hydrochloric acid should be measured. The hydrochloric acid should then be added to the flask containing sodium thiosulfate solution and then the stopwatch should be started. 3) A yellow sulphur precipitate forms in the flask 4) The experiment is then repeated with mixtures of sodium thiosulfate solution and water to see how different concentrations affect the time it takes for the cross to disappear

Question 35

What different ways can you measure the formation of products during a reaction?

Answer 35

- Through looking for precipitation - Through recording the change in mass - By using a gas syringe to measure the volume of gas given off

Question 36

What happens if you heat blue hydrated copper sulfate crystals?

Answer 36

The water is driven off and leaves white anhydrous copper sulfate powder. This reaction is endothermic.

Question 37

What happens if you add water to white anhydrous copper sulfate powder?

Answer 37

You get the blue copper crystals again and energy is given out - this is exothermic

Question 38

What does anhydrous mean?

Answer 38

Without water

Question 39

What is the symbol equation for the thermal decomposition of calcium carbonate?

Answer 39

CaCO3 <=> CaO + CO2

Question 40

Is the thermal decomposition of calcium carbonate an endothermic or exothermic reaction?

Answer 40

Endothermic, as the calcium carbonate is heated and so takes in heat

Question 41

What happens if you increase the concentration of a reactant?(le chantelier)

Answer 41

The system tries to decrease the concentration by making more products

Question 42

What happens if you decrease the concentration of a product?(le chantelier)

Answer 42

The system tries to increase the concentration reducing the amount of reactants