Rates Of Reaction & Energy Changes

Question 1

Name 3 methods determining rates of reactions

Answer 1

Precipitation

Changes in mass (gas given off)

The volume of gas given off

Question 2

Describe the precipitation method

Answer 2

Mixing 2 transparent solutions
Solution will start to go cloudy (producing a precipitate)

Measure how loving it takes for the solution to go cloudy
(Faster it disappears, after the reaction)

Question 3

Name 2 solutions you could use for the precipitation experiment

Answer 3

Hydrochloric acid

Sodium thiosulphate

Question 4

Describe the ‘change in mass’ experiment?

Answer 4

Mix a solution and solid
When gas is released, the lost mass can be measured

The quicker the reading on the balance drops, the faster the reaction

The reaction finishes when the reading stops

Question 5

If harmful gases are given off during the ‘change in mass experiment’ what do you do?

Answer 5

Do the experiment is a fume cupboard

Question 6

Describe the experiment when it shows you the volume of gas given off

Answer 6

Involves a gas syringe (measuring volume of gas given off)

The more gas given off during a set interval, the faster the reaction

Question 7

Name 4 ways you can measure temperature change

Answer 7

Salt dissolving in water

Neutralisation reaction

Displacement reaction

Precipitation reaction

Question 8

Describe salt dissolving in water reaction

Answer 8

Add salt to polystyrene cup of water

Measure change in temperature using thermometer

Question 9

Describe neutralisation reaction

Answer 9

Mixing acid and base —> salt and water

Question 10

What kind of reaction is neutralisation reactions

Answer 10

Exothemric

Question 11

Describe displacement reactions

Answer 11

More reactive element displaces less reactive element in a compound

Question 12

What kind of reaction is displacement reactions?

Answer 12

Exothermic

Question 13

Describe precipitation reactions

Answer 13

2 solutions mixing producing precipitates

Question 14

What kind of reaction are precipitation reactions?

Answer 14

Exothemric

Question 15

Define precipitate

Answer 15

An insoluble salt

Question 16

What does the rate of reaction depend on?

Answer 16

Collision frequency

More successful collisions = faster reaction

Question 17

Define collision frequency

Answer 17

How often particles collide

Question 18

What are the components of the collision theory?

Answer 18

Temperature

Concentration

Surface area

Question 19

What does an increasing temperature do to a reaction?

Answer 19

Increases rate of reaction

Particles move faster = more collisions + energy of collisions

Therefore more successful collisions

Question 20

What does increasing concentration do to a reactions?

Answer 20

Increases rate of reaction

Solution = more particles in fixed volume = more successful collisions

Gas(high pressure) = particles are more crowded = more successful collisions

Question 21

What does an increasing surface area do to a reaction?

Answer 21

Increases rate of reaction

Solid reactant breaks into smaller pieces
Increasing surface are to volume ratio

Particles will have for surface area = more successful collisions

Question 22

Define successful collisions

Answer 22

More parties will collide with enough energy to react

Question 23

Define catalyst

Answer 23

A substance which increases rate of reaction whiteout being chemically changed or used up in a reaction

Question 24

What does a catalyst do in terms of activation energy?

Answer 24

They decrease activation energy

They provide an alternative reaction pathway, that has a lower activation energy

Question 25

Define enzymes

Answer 25

Biological catalysts

Question 26

What are enzymes involved in?

Answer 26

Production of alcoholic drinks

Using enzymes from yeast cells

Question 27

Define activation energy

Answer 27

Minimum amount of energy needed for a bond to break

Question 28

Describe endothermic reactions

Answer 28

Takes in energy from its surroundings

Question 29

How are endothermic reactions shown?

Answer 29

In a fall in temperature

Question 30

Example of endothermic reaction

Answer 30

Breaking bonds

Question 31

Describe exothermic reaction

Answer 31

Gives out energy to its surroundings

Question 32

How are exothermic reactions shown?

Answer 32

Rise in temperature

Question 33

Example of exothermic reaction

Answer 33

Making bonds

Question 34

Equations for overall energy change

Answer 34

Energy required to break bond - energy released by forming bonds

Question 35

Unit for energy change

Answer 35

KJ mol -1