organic chem

Question 1

Fractional distillation

Answer 1

-crude oil is heated until it vaporizes
-vapours pass into the fractionating column which is cooler at the top and hotter at the bottom
-the vapors rise up the column and they condense at a specific height according to their boiling point

Question 2

uses of the fractions

Answer 2

refinery gases- used for domestic heating and cooking
gasoline- used as fuel in cars
kerosene- used as fuel in aircraft
diesel- used as fuel in some cars and larger vehicles eg trains
fuel oil- used as fuel for large ships and in power stations
bitumen - used to surface roads and roofs

Question 3

why is cracking useful

Answer 3

Cracking is useful because short-chain hydrocarbons are more flammable so they are used as fuels for cars
Also alkenes are formed to be used for polymers

Question 4

conditions for cracking

Answer 4

600-700C
a catalyst like silica and alumina

Question 5

what is cracking

Answer 5

Cracking is a process in which long-chain alkanes are converted to alkenes and shorter-chain alkanes

Question 6

What is polymerization

Answer 6

Polymerisation is the joining up of lots of little molecules (monomers) to make one big molecule (polymer)

Question 7

Addition polymerisation

Answer 7

When molecules simply add on to each other without anything else being formed

Question 8

uses for poly…

Answer 8

poly(ethene) - plastic bottles and bags
poly(propene) - crates and ropes
poly(chloroethene) -water pipes or replacement windows
poly(tetrafluroethene) -non stick coatings on pans

Question 9

disposal of addition polymers

Answer 9

they contain strong covalent bonds, making them essentially inert at ordinary temperatures.
they are non biodegradable, meaning they cannot be broken down by bacteria in the environment

Question 10

addition polymer disposal methods (landfill)

Answer 10

adv:
-no greenhouse gases or toxic gases produced from plastics
-cheap
disadv:
-ugly, smelly, and noisy; no one wants to live next to a landfill site
-uses large areas of land
-the waste will be there for thousands of years

Question 11

addition polymer disposal methods (incineration)

Answer 11

adv:
-requires little space
- can produce heat for local homes/offices and produce electricity
disadv:
- it is expensive to build and maintain the plant
-produces greenhouse gases
-releases toxic gases
-the ash produced must still be disposed of in landfill sites

Question 12

length chain: short

Answer 12

low boiling point
high volatility
low viscosity
high flammability

Question 13

length chain: long

Answer 13

high boiling point - attached to each other more strongly, more energy needed to break intermolecular forces
low volatility
high viscosity
low flammability
darker in color

Question 14

test for saturation

Answer 14

• add bromine water and if its saturated, the orange-brown color will remain
• if it is unsaturated it will turn colorless

Question 15

combustion

Answer 15

complete combustion: –>CO2 + H2O
incomplete combustion: –> CO (or C) +H2O

+ oxygen —> carbon dioxide + water

Question 16

incomplete combustion

Answer 16

• products of incomplete combustion contain less oxygen than carbon dioxide
• as well as carbon dioxide and water it produces carbon monoxide (CO), a toxic gas and soot
• CO can combine with haemoglobin and stop your blood from carrying oxygen around the body
• can lead to fainting, coma , death

Question 17

acid rain

Answer 17

• in crude oil when fuels are burnt, sulfur dioxide and nitrogen oxides may be produced
• when they mix with water vapour in clouds they form dilute sulfuric acid and nitric acid
• the rain that falls is called acid rain
• it causes lakes to become acidic and many plants and animals to die as a result

Question 18

alcohols

Answer 18

alc- carboxylic acid
oxidized by potassium dichromate dilute sulfuric acid
(turns from orange to green

microorganisms uses alcohol as energy
- they use oxygen in air to oxidize
- carboxylic acid made as by product

Question 19

production of ethanol

Answer 19

ethene (from crude oil) reacts with steam to make ethanol
-reaction needs temp of 300C and pressure of 60-70 atmospheres
-phosphoric acid is used as a catalyst

fermentation
sugar converted into glucose by yeast
-yeasr contains enzyme (naturally occurring catalyst) speed up
-temp 30C if too hot enzyme in yeast denatures
- keep in no oxygen condition or else turns into ethnic acid (vinegar)
adv: made of renewable resource sugar yeast
dis: isn’t very concentrated, needs to be distilled, purified

Question 20

carboxylic acids

Answer 20

react to form salts
in aqueos soltuions reacts with metal carbonate - forms salt, water, co2
aqueos carbo acid reacts with metals to produce salt and hydrogen

Question 21

esters practical

Answer 21

first add 10 drops concentrated sulfuric acid to boiling tube using a pipette
add about 10 drops ethanoic acid
then add equal volume ethanol
place the boiling tube in a beaker of water and place on a tripod
heat using a bunsen burner until the water starts to boil
after 1 min remove the tube and allow it to cool
pour the mixture into a test tube of sodium carbonate elution and mix, alayer of ester will form on top

Question 22

unsaturated hydrocarbons

Answer 22

hydrocarbons that contains carbon to carbon double bond

saturated - doesn’t contain carbon to carbon double bond

Question 23

suffix

Answer 23

Homologous Series Prefix or Suffix
alkanes(single c to c bond) –ane
alkenes(c to c double bond) –ene
alcohols (OH) –ol
carboxylic acids (C-iiO OH) –oic acid