organic chemistry Flashcards
define hydrocarbon
compound of hydrogen and carbon only
what is meant by the term homologous series
a series of compounds with the same general formula, similar chemical properties, a trend in physical properties and the same functional group
what is a functional group
a group of atoms that determines how a compound typically reacts
define isomerism
molecules with the same molecular formula but different arrangement of atoms
name the stem for organic compounds with 1-6 carbons
meth, eth, prop, but, pent, hex
what is crude oil
a mixture of hydrocarbons
describe the industrial process of fractional distillation
1) crude oil heated until vapourised then enters fractionating column
2) column is hot at bottom and cold at top
3) when the hydrocarbons reach the temperature lower than their boiling point they condense and are drained off
4) the longer hydrocarbons have higher boiling points so they condense at the bottom
5) the shorter hydrocarbons have lower boiling points so they condense at the top
bitumen: uses + number of carbons
road surfaces
70+
fuel oil: uses + number of carbons
large ship fuel
-40
diesel: uses + number of carbons
cars/ large vehicles
-20
kerosene: uses + number of carbons
aircraft fuel
-15
gasoline: uses + number of carbons
car fuel
-8
refinery gases: uses + number of carbons
domestic cooking/heating
-3
what are the trends in physical properties in hydrocarbons
1) get more viscous/ thick as they get longer
2) get darker as they get longer
3) boiling point increases as they get longer
what is a fuel
releases heat when burned
products of incomplete combustion
carbon monoxide, soot (and C02, H20)
complete combustion of hydrocarbons
hydrocarbon + oxygen -> C02+ H20
why is carbon monoxide poisonous
binds with red blood cells and stops them carrying oxygen around the body; lack of oxygen leads to fainting, coma or death
how is acid rain caused (by nitrogen oxide)
in car engines, the temperature is high enough for nitrogen to react with oxygen in the air, forming nitrogen monoxide
nitrogen monoxide reacts with oxygen in the atmosphere to make nitrogen dioxide
nitrogen dioxide dissolves in rain to form dilute nitric acid
how is acid rain caused (by sulfur dioxide)
hydrogen fuels contain sulfur impurities
when these fuels are burnt, sulfut dioxide is formed
SO2 mixes with water vapour to form dilute sulfic acid
what is cracking
splitting up longer chain alkanes into alkenes and shorter chain alkanes
what conditions are needed for cracking
600-700 degrees
silica or alumina catalyst
what is the general formula for alkanes
Cn H(2n+2)
what is the general formula for alkenes
Cn H2n
why are alkanes saturated hydrocarbons
they have the maximum number of H-C bonds (no double bonds) and only contain H and C
describe the reactions of alkanes with halogens in the presence of UV radiation
a hydrogen atom from the alkane is substituted for a halogen
so these are SUBSTITUTION reactions
eg methane + bromine ->bromomethane + hydrogen bromide
what is the functional group for alkenes
C=C
why are alkenes unsaturated
they have a double bond
describe the reactions of alkenes with bromine to make dibromoalkanes
- double bond broken and a bromine atom is added to each of the carbons
- orange bromine water goes colourless
how do you distinguish between alkenes and alkanes experimentally
shake with bromine water:
alkene- goes colourless
alkane- no change
how are addition polymers formed
joining up many small molecules called monomers
explain the problems in the disposal of addition polymers
1) inertness means they are hard to break down so won’t biodegrade
2) produce toxic gases when burnt
What makes a good fuel:
Releases a lot of heat energy (j/kg)
Safe to use and convenient to store
Reasonably cheap and easy to find
Not produce toxic gases
What are the problems with petrol
Disadvantages of using petrol:
Produces CO2 (greenhouse gas)
Not reusable
Can produce harmful gases like carbon monoxide
properties of polyethene
cheap, flexible, can be made into thin films
properties of PVC
tough, electrical insulator, can be made hard or flexible
properties of PFTE
slippery, unreactive
how does limestone reduce acid rain
calcium carbonate (from limestone)
-acidic gas passed through calcium carbonate in
chimney
-(calcium carbonate) neutralises/reacts with
acidic gases
- acidic gases prevented from entering the
atmosphere
Functional group of alcohols
O-H
How can ethanol be oxidised
1) burning in air (complete combustion)
2) microbial oxidation
3) heating with potassium dichromate in dilute sulfuric acid
What are the reactants and products of complete combustion of alcohols
Alcohol + oxygen -> C02 + H20
What is microbial oxidation
Microorganisms use alcohols as an energy source
They oxidise alcohols
Carboxylic acids are made as a bi-product
What happens when ethanol is heated with acidified potassium dichromate
Ethanol -> ethanoic acid
H H H
H-C-C-O-H ————> H-C-C=O
H H H `OH
( heat needed)
How can ethanol be manufactured (using steam)
Ethene reacts with steam to produce ethanol This is an addition reaction Conditions needed: 300 degrees 60-70 atm Phosphoric acid used as a catalyst
How can ethanol be produced by fermentation
Glucose ———-> ethanol + C02 Yeast cells contain enzymes which catalyse this reaction Conditions 30 degrees c Anaerobic
Functional group of carboxylic acids
-COOH
Describe the reaction of carboxylic acids with metals
Carboxylic acid + metal -> salt + hydrogen
Carboxylic acid reaction with Metal carbonate
Carboxylic acid + metal carbonate -> salt + water + C02
What is vinegar
Ethanoic acid dissolved in water
Functional group of esters
COO
What ester is produced from ethanol and ethanoic acid
Ethyl ethanoate
Ethanol + ethanoic acid -> ethyl ethanoate + water
What catalyst is used when forming esters
Acid catalyst (eg concentrated sulfuric acid)
Word equation for the formation of an ester
Alcohol + carboxylic acid -> ester + water
Practical: make an ester
1) add a few drops of concentrated H2SO4 in a boiling tube using a Pipette
2) add 10 drops of ethanoic acid
3) add 10 drops ethanol
4) place boiling tube in beaker of water on tripod
5) Heat using Bunsen Burner until water starts to boil
6) after 1 minute remove tube and cool
7) pour into test tube of sodium carbonate solution+mix
8) a layer of ester should form on top
Describe condensation polymerisation
Polyester formed when dicarboxylic acid monomers and idol monomers react together
What are biopolyesters
Biodegradable polyesters
Can be broken down by living organisms
Decompose so reduce pollutant effect
