Chemistry Paper 2

Question 1

Factors effecting rate of reaction and why

Answer 1

Temperature, surface area, concentration of solution or pressure of gas, if catalyst is present

Question 2

Ways to measure rate of reaction

Answer 2

Precipitate or change in colour
Change in mass(because of gas given off)
Volume of gas given off(using gas syringe)

Question 3

What is meant by equilibrium

Answer 3

At some point reaction reaches equilibrium where the forward reaction and backwards reaction are at the same rate so concentration of each doesn’t change they are still reacting but overall concentration doesn’t change.
Only happens in a closed system where nothing comes in or out

Question 4

How different factors affecting position of equilibrium (le Ch ateliers)

Answer 4

Concentration
If concentration of product is increased some product turns into reactants until it reaches equilibrium
What ever gets increased the equilibrium tries to decrease it

Temperature
One direction is endothermic the other direction is exothermic
So if temperature is changed the equilibrium changes into the direction to get the temperature back to what it was
e.g. temperature is increased so goes towards endothermic side

Pressure
Only effects reactions that include gases
If pressure is changed reaction try’s to counteract e.g. increase pressure reaction goes towards the side with least amount of gas molecules(moles) to try and get the pressure the same

Question 5

Structure of Alkanes

Answer 5

For every carbon 2 hydrogen + 2 extra hydrogen

Question 6

Structure of Alkenes

Answer 6

2 hydrogen for every carbon and a carbon to carbon double bond, Carbon can only make 4 bonds so if it has double bonds it will only be bonded to 1 carbon and 1 hydrogen
They are unsaturated because of the double bond

Question 7

Why do alkenes have smoky flame

Answer 7

When not enough oxygen they undergo incomplete combustion producing carbon, carbon monoxide, carbon dioxide, water the smokiness being from carbon

Question 8

What is a homologous series

Answer 8

Chemicals that have the same functional group so they react same way

Question 9

What is hydrogenation

Answer 9

Alkene reacted with hydrogen in presence of catalyst to form a saturated alkane

Question 10

What happens when halogen react with alkene and what can it be used for

Answer 10

Halogen react with alkene to unsaturated bond
Can be used as a test for Alkene
Bromine can be added and mixed starts colourless if alkene present reacts with is and becomes colourless if not present is cant react because all the other bonds are saturated

Question 11

Describe addition polymerisation and how to draw it

Answer 11

Monomers containing double bonds join together in high pressure and catalyst to make a repeating chain polymer
Monomer is brackets with n on left
Polymer is brackets with bonds coming out and n in bottom left

Question 12

Alcohol formular and structure
and properties

Answer 12

C(n) H(2n+1) OH same as alkanes but instead of a hydrogen on the right you have functional group OH

Properties flammable and completely combust. React with sodium to produce hydrogen
Oxidise with oxygen causing carboxylic acid(that’s why wine smells vinegary after sitting out)
Can dissolve stuff water cant so used in industry as solvents
Can also be used as fuel since it burns cleanly

Question 13

Carboxylic acid names

Answer 13

methanolic acid, ethanoic acid, propanoic acid, butanoic acid

Question 14

How do carboxylic acids react and what is the name of what they form

Answer 14

React like other acids so with a carbonate it produces water ,salt ,carbon dioxide
The salt produced will be something like sodium ethanoate, sodium butonate surname will end in onate

Question 15

What are esters functional group and structure and how are they made

Answer 15

Functional group COO the functional group of the acid (COOH) the hydrogen get replaced by the alcohol
So a carboxylic acid and alcohol react to produce water and ester needs acid catalyst present
Its structure is a carboxylic acid on the left and acid on the right the OH of the acid and OH of the alcohol join together and get replaced by a single oxygen so the extra O and 2H form water

Question 16

Carboxylic acid structure

Answer 16

Like a alkane but the last carbon doesn’t have any hydrogen attached but instead a oxygen double bonded and a OH bonded to it

Question 17

Two types of condensation polymerisation

Answer 17

One can be made using two monomers each with 2 of the same functional group
Can also have one monomer with 2 different functional group

Question 18

What is condensation polymerisation with reactants and how to show it

Answer 18

A diol (two alcohol functional group) and a dicarboxylic acid (two carboxylic acid) each with 2 of the same functional group react together
The reactants have one functional group on the left then a box with bonds(lines) going into a box then another functional group MIRRORED on the right. They each have an “n” in front

The polymer has the same functional group as an ester COO (because alcohol and acid reacting together) a box in between them and functional group mirrored on either side and another box on the far left with brackets and bonds going out “n” in the bottom left
Also has water produced for the same reason as the ester 2nH2O for every repeat of the polymer there is 2 water because there is 2 functional groups in every repeat of the polymer

Question 19

Amino acid structure

Answer 19

amino group on left NH2 and carbon and hydrogen in middle with carboxylic acid functional group on right

Question 20

How are proteins made

Answer 20

Amino acids join in condensation polymerisation the two functional group in the amino acid react together to produce one water and join to each other

Question 21

Different gas tests

Answer 21

Chlorine should bleach damp litmus paper

Hydrogen squeaky pop test when burning hydrogen

Oxygen glowing splint should relight once in oxygen

CO2 bubble it through limewater and it should go cloudy

Question 22

What is a Anion

Answer 22

Ion that gets attracted to anode so negative ion
So Carbonates, Sulphates and Halides

Question 23

Carbonate test

Answer 23

Add substance to dilute acid then connect test tube to test tube of lime water to bubble the gas through if it turns cloudy then CO2 is present

Question 24

Flame test

Answer 24

Can burn metals and look at their colour~
Lithium Crimson
Sodium yellow
Potassium lilac
Calcium orange-red
Copper green

Question 25

Metal with NaOH test

Answer 25

Calcium white percipitate
Magnesium white
Aluminum white then back to clear
Copper Blue
Iron 2+ green
Iron 3+brown

Question 26

Halide test

Answer 26

Add mixture to dilute nitric acid and add silver nitrate
The silver reacts with the halide to give a precipitate

Chlorine White (milk)
Bromine Cream (cream)
Iodine Yellow (butter)

Question 27

What is a cation

Answer 27

Ion that is attracted to the cathode so positive ions

Question 28

Sulphate test

Answer 28

Add HCL acid to get rid of any traces of carbonate then add Barium Chloride and a white precipitate will form if sulphate is present

Question 29

Formulation

Answer 29

A precise mixture with a certain purpose

Question 30

How has the atmosphere changed

Answer 30

Now it has 78% nitrogen 21% oxygen
First billion year volcanoes erupted giving out CO2, water vapour , small amount of nitrogen

Water vapour cooled and formed oceans, the CO2 dissolved in it and created precipitates causing sediments to form over time, animals used CO2 to make shells.

2.7 billion years ago algae evolved that used up carbon dioxide for photosynthesis and released oxygen decreasing amount of CO2 and increasing amount of Oxygen.
Over time more plants evolved increasing amount oxygen

Question 31

How to tell if something is pure

Answer 31

The MP and BP will be a range and the boiling point will be higher than if it was pure and the melting point will be lower than if it was pure

Question 32

What is the Rf value

Answer 32

How soluble the solute is in the solvent i.e. how far has the ink travelled compared to the solvent
So distance travelled by substance/ distance travelled by solute

Question 33

Types of cracking and how to do them

Answer 33

Catalytic cracking vapoured long hydrocarbons passed over hot catalyst

Steam cracking vapoured long chain hydrocarbon mixed with steam at high temperature

Question 34

Explain greenhouse effect

Answer 34

Sun gives out short wavelength radiation that goes through the atmosphere then gets absorbed by the earth and reflected back as long radiation, the long radiation then is absorbed by the greenhouse gases and re-radiated back trapping the long radiation and keeping the earth warm
Without it no life would exist but deforestation, agriculture, burning fossil fuels releases too many greenhouse gases

Question 35

Effect of climate change

Answer 35

Extreme weather, melting glaciers causing rise in sea level, temperature change

Question 36

Examples of air polution

Answer 36

Global dimming as a result of soot and other particulates that are formed because of incomplete combustion blocking out the sun

Carbon monoxide poisoning from incomplete combustion causing oxygen nit to be carried in the blood

Nitrogen oxides nitrogen and oxygen react in the heat of a engine during combustion causing nitrate oxide

Sulphur dioxide sulphur impurity’s in fossil fuels react with oxygen when fossil fuels are burnt

Acid rain caused by sulphur dioxide and nitrogen oxides reacting with rain water causing acid rain that corrodes building and kills plants

Question 37

What is rust and what is needed to produce it

Answer 37

Iron + Oxygen+ water = hydrated iron oxide

Question 38

Experiment to show rusting

Answer 38

3 test tubes
First one iron nail and boiled water(to remove any dissolved oxygen) with layer on oil on top so no oxygen gets in

Second one Iron nail with calcium chloride(to remove water) and stopper on top to stop moisture getting in so no water

Third one nail with water and air so there is both water and oxygen should be the only one that reacts

Question 39

Why does aluminium corrode less than iron

Answer 39

Hydrated iron oxide flakes exposing more iron to the air while aluminium oxide doesn’t flake but stays on as a flat layer

Question 40

Ways to prevent rusting

Answer 40

Paint
Electroplating
Greasing
all barriers to stop exposure to oxygen and water

Sacrificial method place more reactive metal like zinc close to it so that reacts rather than the iron

Galvanising is a mixture of both barrier and sacrificial method using zinc

Question 41

Different ways to make potable water

Answer 41

Desalination Boil the sea water to form steam then condense the water to make pure water

Fresh water Filtration passed through a wire mesh and sand to filter out any solid bits then sterilisation where chlorine is added or uv light is used

Reverse osmosis Water is forced through a semi-permeable membrane which only allows water through

Question 42

How is waste water treated

Answer 42

First screened to remove any large objects

Then let to settle in a sedimentation tank where there is effluent on top and sludge on the bottom

The sludge is taken away to be digested by anaerobic bacteria to digest releasing bio gas that is used as fuel and the rest of the sludge as fertiliser

The effluent in top has air bubbled through so there is oxygen for aerobic bacteria to digest the harmful microbes and other organic material the water is then released back into the environment

Question 43

Formular for ammonia

Answer 43

NH3

Question 44

Describe harbour process

Answer 44

Nitrogen and hydrogen added in ratio 1:3 heated at high pressure over catalyst to make ammonia not all the hydrogen and nitrogen react so the gases leaving are cooled so ammonia condenses and is taken away while the gases are recycled back