Organic Part 1, 2 and 3 Flashcards
4.1 Hydrocarbons
Compound made up of ONLY hydrogen and carbon atoms
4.2 Molecular formula of ethane
C2h6
4.2 Empirical formula of ethane
CH3
4.2 Displayed formula of ethane
H H
/ /
H - C - C - H
/ /
H H4.2 Structural formula of ethane
CH3CH3
4.2 General formula of alkanes
CnH2n+2
4.3 Homologous series properties
- same general formula
- same functional group (e.g. alkanes)
- trend in boiling point
- same chemical properties (reactivity)
- differ by CH2
4.3 functional group
- group of atoms that determines the reactivity of a molecule
4.3 isomerism
- same molecular formula, different structural/displayed formula
4.6 classifying reactions of organic compounds
Substitution - straight swap
Addition - two things add up to make one molecule
Combustion - produces carbon dioxide and water
4.19 general formula of alkanes
CnH2n+2
4.20 why are alkanes classified as saturated hydrocarbons
There are only carbon single bonds
4.24 general formula for alkenes
CnH2n
4.25 explain why alkenes are classified as unsaturated
Because it has a carbon double bond
4.27 reaction of alkenes with bromine water to produce dibromoalkanes
- addition reaction
- example: ethene + bromine = dibromoethane
why are alkenes more useful than alkanes
- they are more reactive due to the carbon double bond
- they are used to make polymers
4.28 how can bromine water be used to distinguish between an alkane and an alkene
- alkane = no change to bromine water (orange)
- alkene - bromine water will be decolourised
4.7 what is crude oil
- a mixture of hydrocarbons
4.8 fractional distillation
- heat crude oil until it evaporates
- fractionating column is very hot at the bottom and cool at the top
- crude oil enters fractionating column and vapour rises
- hydrocarbons with high boiling points will immediately condense into liquid lower down and are tapped off at the bottom of the column
- hydrocarbons with lower boiling points will rise up the column and condense at the top to be tapped off
4.9 names and uses of main fractions
COOLEST TO HOTTEST:
- refinery gases - domestic heating and cooking
- gasoline (petrol) - fuel for cars
- kerosene - fuel in aircraft
- diesel - fuel in larger vehicles
- fuel oil - fuel for large ships and power stations
- bitumen - surface roads and roofs
4.10 trend in colour, boiling point and viscosity
longer chain hydrocarbons:
- more viscous
- higher boiling point
- darker in colour
- less volatile
shorter chain hydrocarbons:
- less viscous
- lower boiling point
- light in colour
- more volatile
4.11 what is released when fuel is burned
- heat energy
4.12 products of complete and incomplete combustion
complete combustion:
- carbon dioxide
- water
incomplete combustion:
- water
- soot
- carbon monoxide
4.13 why is carbon monoxide bad
- binds with red blood cells and prevents them from carrying oxygen around the body
4.14 what does the temperature in car engines allow
- allows nitrogen and oxygen to react, forming oxides of nitrogen
4.15/4.16 sulphur dioxide
- combusting impurities in hydrocarbon fuels results in formation of sulphur dioxide
- sulphur dioxide mixes with water vapour in clouds and creates acid rain which poisons plants and animals as well as corroding buildings
4.17/4.18 cracking
- more demand for short chain hydrocarbons
- long chain hydrocarbons are cracked using high temperatures (600-700) and silica (catalyst)
- produces alkenes
