Chemistry 1b

Question 0

How does cracking occur?

Answer 0

Heat long chain
Vapour passed over powdered aluminium oxide catalyst at 400 - 700 degrees Celsius
Form alkanes and alkenes

Question 1

What is cracking?

Answer 1

Splitting up long hydrocarbons.

Question 2

What are alkenes?

Answer 2

Have a double bond
Unsaturated
CnH2n

Question 3

How do you test for alkenes?

Answer 3

Bromine water decolourises in presence of double bond as double bond opens up and forms bonds with bromine. (Previously orange).

Question 4

How can ethene produce ethanol?

Answer 4

Hydrated with steam
Cheap
Non renewable

Question 5

How can ethanol be made?

Answer 5

Fermentation of sugar
Renewable
Cheap
Needs to be purified

Question 6

How can alkenes be used to make polymers?

Answer 6

Polymerisation

Join small alkenes (monomers) to form polymers

Question 7

What created flexible polymers?

Answer 7

2000 pressured and 200 degrees Celsius

Question 8

What makes rigid polymers?

Answer 8

60 degrees Celsius and few atmospheres pressures with a catalyst

Question 9

What are the uses of polymers?

Answer 9

Lycra fibre
Waterproof coatings
Biodegradable packaging
Memory foam

Question 10

How are plant oils extracted?

Answer 10

Crushed, press, centrifuge separates

Solvents get oil, distillation refines by getting rid of solvents, water and impurities

Question 11

Why are vegetable oils used in food?

Answer 11

Essential fatty acids
Energy
Vitamin E

Question 12

What benefits does vegetable oil have for cooking?

Answer 12

Lower boiling point
Different flavour
Increases energy

Question 13

What do unsaturated oils contain?

Answer 13

Double bonds

Question 14

How are unsaturated oils hydrogenated?

Answer 14

Reacted with hydrogen over a nickel catalyst at 60 degrees Celsius

Question 15

What are the properties of hydrogenated vegetable oils?

Answer 15

High melting points =spreads
Cheaper
Trans fats =bad for you

Question 16

What is bad about vegetable oil?

Answer 16

Saturated = increase cholesterol

Fattening

Question 17

What at emulsions?

Answer 17

Droplets of liquid suspended in another liquid.

Question 18

What are uses of emulsions?

Answer 18

Paint
Mayonnaise 
Salad dressing 
Milk 
Ice cream 
Moisturising lotion

Question 19

What are emulsifiers?

Answer 19

Hydrophilic head and hydrophobic tail

Question 20

What are the prod and cons of emulsifiers?

Answer 20

Pros - longer shelf life
- lower in fat
Cons - allergies

Question 21

What led to the theory of continental drift?

Answer 21

Matching layers of rocks
Fit like jigsaws
Fossils found in ‘wrong places’

Question 22

Why wast Wegener’s theory accepted for many years?!

Answer 22

Impossible tidal forces
Used inaccurate data
Wasn’t proper geologist

Question 23

What is the structure of earth?

Answer 23

Very thin crust
Mantle
Iron and nickel core

Question 24

What are tectonic plates?

Answer 24

Plates in mantle Convection currents created by radioactive decay move plates Sudden movement causes earthquake

Question 25

Why can't scientists predict earthquakes and volcanic eruptions?

Answer 25

Sometimes molten rock cools instead of erupting | Impossible to predict exactly when they'll move

Question 26

What is phase 1 of the evolution of the atmosphere?

Answer 26

Earths surface molten Volcanoes gave out gases Oceans formed by water vapour condensing

Question 27

Why was phase 3 of the atmosphere evolving?

Answer 27

Green plants and algae photosynthesised and saw absorbed CO2 Plants and algae died and buried under layers of sediment, trapping carbon

Question 28

What was phase 3 of the atmosphere in evolution?

Answer 28

Oxygen build up killed early organisms | Ozone layer blocked harmful rays so more complex organisms evolved

Question 29

What is the primordial soup theory?

Answer 29

- Earth's atmosphere was nitrogen hydrogen ammonia and methane - lightning struck causing a chemical reaction forming amino acids - amino acids collected In primordial soup out of which life gradually crawled - Miller-Urey carried out experiment - amino acids were made but not as many as on earth

Question 30

How is air fractionally distilled?

Answer 30

1- air is filtered to remove dust 2- cooled to -200•c 3- water vapour condenses and removed 4- CO2 freezes and removed 5- liquified air enters column and heated slowly 6- gases separated out by fractional distillation

Question 31

How does CO2 affect the climate and oceans?

Answer 31

- global warming | - acidic sea which kills coral and shellfish