Facts In Books

Question 1

How does a catalyst work

Answer 1

They lower the activation energy as they provide an alternative pathway at a lower energy level so more successful collisions occur
^^ meaning they speed up reactions

Question 2

What do catalysts do and not do

Answer 2

They speed up reactions but are not used up

Question 3

What is the meaning of a reversible reaction

Answer 3

A reaction that can be changed back to its original form > the reaction can go in both directions

Question 4

What is the collision theory

Answer 4

In a chemical reaction, reactant particles must collide and the colliding particles must have enough energy for the collision to be successful

Question 5

Give 2 ways you can measure the rate of a reaction

Answer 5

Amount of reactant used up (divide) time
Or
Amount of product made (divide) time

Question 6

What is the effect of temperature on rates

Answer 6

If increased the reactant particles move more quickly which means they have more energy and collisions happen more therefore the rate of reaction increases

Question 7

What effect does a catalyst have on a rate of reaction

Answer 7

They lower the activation energy, providing a different pathway and a lower energy level so more successful collisions occur

Question 8

What affect does the surface area have on rates of a reaction

Answer 8

The fate will increase as more particles are exposed to the other reactant and more collision will therefore happen

Question 9

What is the effect of concentration/ pressure on rates of a reaction

Answer 9

More reactant particles in same volume so a greater chance for particles to collide and rate increased

Question 10

What is the mass of a substances measured with

Answer 10

Balance

Question 11

Volume of a gas is measured with?

Answer 11

Gas syringe or burette

Question 12

What factored effect rates of a reaction

Answer 12

Temperature change 
Concentration of a dissolved reactant 
Pressure of a reacting gas 
Surface area is changed 
Catalysts

Question 13

Whats the activation energy

Answer 13

The minimum energy needed for particles to react

Question 14

What does an iron catalyst do

Answer 14

Makes ammonia from nitrogen and hydrogen

Question 15

What’s a platinum catalyst effect

Answer 15

Making ammonia from nitrogen and hydrogen

Question 16

What is bond breaking

Answer 16

An endothermic reaction because energy must be supplied to break existing bonds

Question 17

What is bond formation

Answer 17

Exothermic reaction because energy is released when new bonds are formed

Question 18

How can you calculate the overall energy change for a reaction

Answer 18

Using bond energies

Question 19

What’s the equation for energy change

Answer 19

Energy if bond breaking - energy if bond making

Question 20

How do you work out the amount of energy used in bond breaking

Answer 20

Adding up the bond energies of all the bonds in the reactants

Question 21

How do you work out the amount of energy given out from bond making

Answer 21

Adding up the bond energies of all the bonds in all the products

Question 22

Give some facts on ammonia

Answer 22

It breaks down when it is heated

It’s a colourless gas

Question 23

What happens when ammonium chloride breaks down

Answer 23

It firms ammonia gas and hydrogen chloride gas

Question 24

What is a closed system

Answer 24

When I ether reactants nor products can enter or leave

Question 25

What is the position of equilibrium

Answer 25

When reversible reactions reach a balance point, where the amount of reactants and the amount of products formed remain constant

Question 26

When is an equilibrium reached

Answer 26

When the forward and reverse reactions occur at the exactly same rate

Question 27

What is le chateliers principle | To do with dynamic equilibrium

Answer 27

If a dynamic equilibrium is disturbed by changing the conditions, the reaction moves to conteract change

Question 28

How is a does concentration change the position of equilibrium

Answer 28

If more of a reactant is added, the system would work by removing this reactant and making more of the products

Question 29

How does temperature change the position of equilibrium

Answer 29

Decreasing the temp moves the position of E in the direction of the exothermic reaction Increasing the temp moves the position of E in the endothermic direction

Question 30

How does changing the pressure effect the post Position of equilibrium

Answer 30

Increasing the pressure moves the position of E to the suede with the least number of molecules

Question 31

What happens if you add a catalyst to an equilibrium reaction

Answer 31

It reduces the time to reach equilibrium but doesn't change the position of E

Question 32

Why do particles need to smash into one another

Answer 32

So the bonds are broken and new substance is made

Question 33

What happens if activation energy is low

Answer 33

Particles don't need to collide with much energy to react | Meaning they'll react as soon as they're mixed

Question 34

What does carbon dioxide produce during a reaction

Answer 34

Fizzing

Question 35

What's is the concentration

Answer 35

Amount of molecules dissolved in a volume of water

Question 36

What can't you do if two reactants are gases | And what the alternative thing to do

Answer 36

Increase the concentration | So you increase the pressure

Question 37

How can the rate of reaction between marble chips and hydrochloride acid be changed

Answer 37

Changing the temperature and surface area of reactants

Question 38

Why are powders like icing sugar flour and custard powder dangerous

Answer 38

They react very quickly as they have very large surface areas so they need to avoid naked flames

Question 39

What are the pros of catalysts

Answer 39

Very small amounts can be used and they can be used again and again thus many industrial chemical reactions use them

Question 40

What is a drawback if catalysts

Answer 40

They are very specific to what they can be used on

Question 41

What are catalysts in living things called

Answer 41

Enzymes | Sometimes known as biological catalysts

Question 42

Where do reactions stop

Answer 42

One or both of the reactants are used up

Question 43

What is the reactant called that causes the reactions to stop

Answer 43

Limiting reactant

Question 44

How to measure the rate of reaction on a graph on a fine point on the graph

Answer 44

Make a tangent (straight line) on the curve of where the point asked is Then draw a right angles triangle and find the steepness of the tangent by dividing the height by the width Thus = vol. gas collected (divided) time taken

Question 45

To measure reactions rates what do you need to do

Answer 45

Observe the reaction at time intervals see amount of gas released Change in mass The colour or appearance change