Organic Chemistry

alkenes test/result

-reacts with Br2(aq) immediately (addition reaction)

• alkenes go colourless in bromine water

• addition of halogens=test for double bonds

crude oil

a mixture of hydrocarbons

alkanes test/reactions

• alkanes react with Br2 (aq) in presence of uv light (goes colourless)

• undergoes substitution reaction

functional group

part of an organic molecle responsible for it’s chemical reaction

alkene general formular and functional group

• C_nH_2n

• C=C

molecular formular

• exact number of atoms

empirical formula

• simplest ratio

displayed formula

shows all atoms and all bonds

organic compound

a compound that is carbon based

why do we crack alkanes

• smaller alkanes used for fuel = high demand

• breaking long chains meets our needs and gives alkenes

conditions for cracking

• 600-700^oC

• Alumina/silica

steps of fractional distillation

1. crude oil heated until it vaporises

2. mixture of gases enter column

3. top hotter, bottom cooler

4. gases rise, cool and condense at boiling point

5. tapped off at height

6. small molecules collected at the top, long at the bottom

fractions

(rlly good kids deserve fancy biscuits)

1. refinery gases

2. gasoline

3. kerosene

4. diesel

5. fuel oil

6. bitumen

isomers

2 compounds that have the same molecular formular but a different displayed formular

hydrocarbon

a compound made of hydrogen and carbon only

saturated

contains only single C-C bonds

unsaturated

contains 1+ C=C double bonds

what is released when burning hydrocarbons

COMPLETE

• CO₂ - greenhouse gases

INCOMPLETE

• C particulates - respiratory issues, global dimming

• Sulfur dioxide from impurities - acid rain, ph in lakes, limestone

  • nitrogen oxides (car engines) - acid rain (catalytic converters

homologous series

compounds with…

• same general formula

• similar chemical properties

• a trend in physical properties

• differ by CH₂

substitution reactions

• swapping of one atom for another atom (or groups)

ALKANES

Addition reaction

• adding a substance to another

  2 substances —> 1 substance

ALKENES

longer chains are…

• darker colour

• very viscous

• higher boiling point

• non flammable (smokey flame)

alkane general formula + functional group

C_nH_2n+2

saturated

smaller chains are

• lighter colour

• non viscous

• lower boiling point

• flammable (burns with clean flame)

general formula

• can be applied to whole homologus series

structural formula

• gives us imformation on how atoms are arranged

Refinery gases used for

heating + cooking in homes

gasoline used for

petrol for cars

kerosene used for

jet fuel

diesel oil used for

trucks/lorries

fuel oil used for

big ships/ tankers

industrial heating

bitumen used for

road surfaces

alcohol functional group

-O-H

structure of ethanol (add more c for others)

use of alohol

• fuels

• solvents (perfumes + aftershaves), dissolves solutes that can’t be dissolved in water

• ethanol in alcoholic drinks (fermentation)

fermentation of carbohydrates conditions

• approx temp = 30

• pressure = normal

• catalyst - enzymes in yeast

• ABSENCE OF AIR

conditiond for reaction of ethene with steam

• temp = 300

• pressure = 60-70 atm

• catalyst = phosphoric acid

fermentation raw material + type

sugar cane, renewable

ethene with steam raw material + type

crude oil, finite

fermentation type of process, speed, purity

• batch

• slow

• impure

ethene with steam type of process, speed, purity

• continuous

• fast

• pure

functional group of carboxylic acid

-COOH

functional group of esters

-COO-

2 ways to oxidise alcohols

• burning in air

• microbial oxidation

word equation ethanol burning in air

ethanol + oxygen —> carbon dioxide + water

microbial oxidation word equation

Ethanol + oxygen —> ethanoic acid + water

structure methanoic acid (add more c for others)

carboxylic acids are ____ acids

weak

what is a strong acid?

all the molecules break down to form H⁺ ions when added to water

what is a weak acid?

only a small fraction of the molecules break down to form H⁺ ions when added to water

Acid + carbonate —->

(+observations)

salt + carbon dioxide + water

fizzes gently

oxidation of alcohols leads to

carboxylic acids

Acid + metal —→

salt+ hydrogen

fizzes gently

vinegar is

an aqeous solution containing ethanoic acid

how are esters formed

carboxylic acid reacts with alcohol in presence of sulfuric acid catalyst

what is a polymer

a long chain molecule made by lots of smaller molecules joined together

how to molecules containing C=C bond form polymers

what type of reaction?

C=C bonds join together to form a chain (polymer) no other products are made

addition polymerisation reaction

3 examples of addition polymers and uses

polyetherne - plastic bags

poly tetrafluoroethene - teflon surfaces, non stick kitchenware.

poly chloroethene - water pipes

what is a repeating unit of a polymer

smallest structure with, joined together, forms a polymer

repeating unit of addition polymers

change double bond to single, extend single bonds on either end

what is a condensation polymer

• polymer made in condensation polymerisation

• molecules join together, also release small molecule (H2O or HCl, etc)

polyesters

polyamides

what are biodegradable polyesters called

biopolyesters

how to draw caboxylic acid and alcohol reaction

1. remove O-H from carboxylic acid

2. remove H from alcohol

3. but them togehter

4. name alcohol first ( bit with no double bond)

5. -yl -anoate

are esters volatile

yes

problems disposing of addition polymers

• inert, strong C-C bonds, can’t biodegrade = landfill

• toxic gases when burnt

2 things in a condensation polymer

dicarboxylic acid and diol

oxidising agent for alcohols + colour change

potassium dichromate in sulfuric acid

orange → green