Organic Chemistry and the Uses of Chemicals

Question 1

What is the order of names of prefixes in alkanes, alkenes, alcohols, and carboxylic acid?

Answer 1

Meth
Eth
Prop
But
(Pent)

Question 2

What is the functional group of alcohols?

Answer 2

-OH

Question 3

What is the general formula of alcohols?

Answer 3

CnH2n+1OH

Question 4

How can you turn an alcohol into a carboxylic acid?

Answer 4

Oxidise it using an oxidising agent

Question 5

What is the functional group of carboxylic acids?

Answer 5

-COOH

Question 6

What is the general formula of carboxylic acids?

Answer 6

Cn-1H2n-1COOH

Question 7

What is the formula for fermentation?

Answer 7

C6H12O6 –> 2C2H5OH + 2CO2

Question 8

What is a homologous series?

Answer 8

A family of molecules which have the same general formula, functional group and similar chemical properties

Question 9

How can you make a solution of ethanol by fermentation?

Answer 9

Mix yeast and a solution of a carbohydrate e.g. glucose in a clean container. Seal it and leave it at a temperature between 30 and 49 degrees C. When the concentration of alcohol reaches 10-20%, the reaction stops as the yeast gets killed by the alcohol. The yeast falls to the bottom of the container and you can take the ethanol solution from the top.

Question 10

How can you reach ethanol concentrations of more than 20%?

Answer 10

Use fractional distillation: ethanol has a lower boiling point that water, so it evaporates and rises up the column while the water stays liquid. Condense the ethanol vapour with a Liebig condenser and collect it in a flask.

Question 11

How would you investigate how good different alcohols are as fuels?

Answer 11

Put some alcohol in a spirit burner using gloves and measure its mass
Measure 100cm^3 of distilled water into a copper calorimeter. Use a draught excluder, put a thermometer in, and put an insulating lid on
Record the initial temperature and light the wick. Stir the water throughout with the thermometer and blow out the burner when temperature rise reaches 20 degrees C.
Reweigh the burner and repeat with different alcohols

Question 12

What is the trend of alcohol efficiencies as fuel?

Answer 12

The longer the carbon chain, the more efficient the alcohol

Question 13

What are nanoparticles?

Answer 13

Particles 1-100 nanometers (1x10-9 m) across, such as fullerenes. They have different properties from the bulk chemicals they are made from.

Question 14

Why do nanoparticles have different properties to wider particles?

Answer 14

They have a larger surface area to volume ratio, so a much greater proportion of their atoms are available to interact with other substances.

Question 15

What are some uses of nanoparticles?

Answer 15

Catalysts
Cosmetics such as sunscreens as they have better protection and do not leave white marks
Nanomedicines e.g. delivering drugs as they are absorbed more easily
Tiny electric circuits
Making plastics in sports equipment more durable
Silver nanoparticles are added to surgical masks and wound dressings as they have antibacterial properties

Question 16

What are some problems with nanoparticles?

Answer 16

We do not know all the side effects or long term health impacts yet
Some nanoparticles used in medicine do not break down easily so could start to build up in cells
Some could cause lung inflammation if breathed in

Question 17

What are some different polymers and their uses?

Answer 17

Strong, rigid polymers e.g. high density poly(ethene) are used to make water pipes
Light, stretchy polymers e.g. low density poly(ethene) are used for plastic bags and bottles
Poly(styrene) foam is used as packaging and as a thermal insulator
Heat resistant polymers such as melamine resin and poly(propene) are used in plastic kettles

Question 18

What are ceramics and some examples?

Answer 18

Materials made by baking substances to produce a brittle, stiff material. Clay can be hardened at high temperatures and used as a building material such as bricks.
Glass, made by melting and cooling limestone, sand, and sodium carbonate, is transparent and strong

Question 19

What are composites and some examples?

Answer 19

Materials made of one material (the reinforcement) embedded in another (the matrix or binder). Carbon fibre composites use carbon atoms held together in a polymer resin matrix. They are strong and light and used in sports cars and aerospace

Question 20

What are advantages and disadvantages of polymers, ceramics, metals, and composites?

Answer 20

Polymers - adaptable, cheap, less dense, insulators. Can degrade and break down
Ceramics - insulators, strong, hard wearing, don’t degrade or corrode. Brittle and stiff
Metals - good conductors, malleable, some corrosion resistant, less brittle. Can deform, some corrode
Composites - versatile. Expensive

Question 21

What is condensation polymerisation?

Answer 21

Polymerisation usually involving two different types of monomer, which react and form bonds, making chains. Each monomer must contain at least two functional groups, one at each end, which form bonds, losing small molecules at the same time.

Question 22

How are polyesters created?

Answer 22

They form when dicarboxylic acid monomers (two -COOH groups) and diol monomers (two -OH groups) react, forming an ester link. Molecules of water are lost.

Question 23

What are some natural polymers and their monomers?

Answer 23

DNA, made from 4 different nucleotides
Proteins, made from amino acids
Starch and cellulose: large carbohydrates made from smaller carbohydrates (sugars), which contain carbon, oxygen, and hydrogen

Question 24

What is a life cycle assessment?

Answer 24

An assessment looking at each stage of the life of a product, working out the potential environmental impact at each stage.

Question 25

What are the stages of a life cycle assessment?

Answer 25

Choice of material - is it renewable, is it damaging to extract
Manufacturing - energy use, pollution, waste products, water use
Product use - does usage harm the environment e.g. cars
Disposal - is it recycled, incinerated, or put in landfill

Question 26

What are fuel cells?

Answer 26

Electrical cells that are supplied with a fuel and oxygen and use energy from the reaction to produce electrical energy efficiently, producing a voltage across the cell until one of the reactants is all used up

Question 27

What are hydrogen fuel cells?

Answer 27

Fuel cells that react hydrogen and oxygen to produce water (2H2 + O2 –> 2H2O) and energy

Question 28

What are advantages of hydrogen fuel cells?

Answer 28

Advantages: More efficient than batteries and power stations as electricity is produced directly and heat produced can also be used for energy, leading to >80% efficiency
No moving parts
No conventional pollutants like greenhouse gases, nitrogen oxides, and sulphur dioxides

Question 29

What are disadvantages of hydrogen fuel cells?

Answer 29

Hydrogen is a gas so takes up lots of space and needs pressurised tanks
Hydrogen is explosive so difficult to store safely
Hydrogen is often made from hydrocarbons (from fossil fuels) or by electrolysis of water (which uses electricity)