C2b

Question 1

What is activation energy?

Answer 1

The minimum energy required in a collision for particles to react

Question 2

What 4 factors affect the rate of a chemical reaction?

Answer 2

Temperature, pressure or concentration, surface area, catalysts

Question 3

What is the experiment for the effect of temperature on rate of reaction? How does it work?

Answer 3

1) Sodium thiosulfate and HCl
Clear solutions make yellow precipitate
Time mark fading, repeat at different temperatures
2) Particles more faster - higher chance of collision, higher energy = more successful

Question 4

What is the experiment for the effect of concentration on rate of reaction? How does it work?

Answer 4

1) Mg metal and HCl
H gas released - mass balance
Regular readings, repeat at different concentrations
2) Particles closer together, higher chance of collision

Question 5

What is the experiment for the effect of surface area on rate of reaction? How does it work?

Answer 5

1) Marble chips + HCl
Gas syringe of CO2 at regular intervals
Repeat more crushed up
2) More particles available to react

Question 6

What is the experiment for the effect of catalysts on rate of reaction? How does it work?

Answer 6

1) Decomposition of hydrogen peroxide
Measure O gas with syringe
Manganese IV oxide catalyst
2) Lowers Ea, provides surface for particles to stick to

Question 7

What is a catalyst?

Answer 7

A substance that speeds up the reaction without being changed or used up

Question 8

What are the advantages and disadvantages of using catalysts in a reaction?

Answer 8

+ Saves energy, environment, time, money

- Specific to reaction, expensive, can be poisoned

Question 9

What is the equation for the rate of a reaction?

Answer 9

Rate = change in reactant / time

Question 10

What are the three methods of measuring a reaction?

Answer 10

1) Precipitation - product clouds solution, time how long it takes for mark to disappear
2) Change in mass - gas given off
3) Volume of gas given off - with gas syringe in given time period

Question 11

What is an exothermic reaction?

Answer 11

A reaction that transfers (heat) energy to the surroundings, usually shown by a rise in temperature e.g. combustion, neutralisation, oxidation - hand warmers

Question 12

What is an endothermic reaction?

Answer 12

A reaction that takes in (heat) energy, usually shown by a fall in temperature e.g. thermal decomposition, sports injury packs

Question 13

What is the equation for neutralisation?

Answer 13

Acid + base = salt + water

H+ + OH- = H2O

Question 14

What is the difference between a base and an alkali?

Answer 14

Alkali = a base that can dissolve in water

Question 15

What is the equation for an acid reacting with a metal?

Answer 15

Acid + metal = Salt + hydrogen

Question 16

Why is the reactivity series relevant in a neutralisation reaction?

Answer 16

Any metal below H will not react

Question 17

Are (hydr)oxides soluble or insoluble?

Answer 17

Insoluble

Question 18

What is the equation for an acid reacting with a metal (hydr)oxide?

Answer 18

Acid + (hydr)oxide = Salt + water

Question 19

What is the Haber process?

Answer 19

Rare neutralisation reaction as no water produced
Ammonia + Nitric acid = Ammonium nitrate
NH3 + HNO3 = NH4NO3

Question 20

Which three salts are insoluble?

Answer 20

Lead Chloride (PbCl2)
Silver Chloride (AgCl)
Lead Sulfate (PbSO4)

Question 21

What are the two ways to make soluble salts?

Answer 21

Using a metal or insoluble (hydr)oxide

Using an alkali

Question 22

How do you make soluble salts using a metal or insoluble (hydr)oxide?

Answer 22

1) Excess metal to make sure all acid used up, stir
2) Filter excess
3) Evaporate

Question 23

How do you make soluble salts using an alkali?

Answer 23

1) Add exact amount of alkali to neutralise acid using universal indicator
2) Repeat without UI
3) Evaporate water

Question 24

How do you make an insoluble salt?

Answer 24

1) Pick solutions with ions you need

2) Once salt precipitated (lying at bottom), filter, wash ,dry

Question 25

What can a precipitation reaction to make an insoluble salt be used for?

Answer 25

Remove unwanted ions from water - treat sewage | Ca and Mg removed to make water hard - stops soap lathering

Question 26

What is electrolysis?

Answer 26

The splitting up of a substance with electricity

Question 27

What carries electricity in electrolysis?

Answer 27

Electrolyte - liquid with free ions (when a salt is molten it will conduct electricity)

Question 28

OIL RIG?

Answer 28

Oxidation is Loss | Reduction is Gain

Question 29

What is the difference between a cation and an anion?

Answer 29

``` Cation = positive Anion = negative ```

Question 30

What is the difference between a cathode and an anode?

Answer 30

``` Cathode = negative Anode = positive ```

Question 31

Why is cryolite used in the electrolysis of aluminum oxide (bauxite ore)

Answer 31

To lower melting point from 2000 to 900 - save energy and money

Question 32

Why is CO2 produced in the electrolysis of aluminum oxide?

Answer 32

Anode made from carbon so needs to be replaced

Question 33

Why is the reactivity series important in electrolysis?

Answer 33

If both metal+ and H+ are present, metal will stay in solution as more reactive

Question 34

What are halide ions?

Answer 34

Br, I, Cl - if these are present in a solution they will be formed. If not O2 is released

Question 35

What is produced in the electrolysis of brine (NaCl solution)?

Answer 35

Cl2 gas H2 gas NaOH

Question 36

What are Cl and NaOH used for?

Answer 36

Cl - bleach + plastics | NaOH - make soap

Question 37

What are the half equations for the electrolysis of Al2O3?

Answer 37

Cathode: Al3+ + 3e- = Al Anode: 2O2- - 4e- = O2

Question 38

What is electroplating?

Answer 38

Coating the surface of an object with a metal

Question 39

What needs to be in the electrolyte of any electroplating reaction?

Answer 39

Metal ions from the metal you want to coat an object with

Question 40

What charges do the pure metal and object have in electroplating?

Answer 40

Pure metal - positive | Object - negative

Question 41

Why do we use electroplating?

Answer 41

Decoration - cheaper to coat | Conduction