Organic Chemistry Introduction Flashcards
Define empirical formula.
Define empirical formula.
Simplest whole number ratio of atoms in a molecule
Define molecular formula.
Define molecular formula.
Gives the actual number of atoms of different elements in a molecule
Define displayed formula
Define displayed formula
Shows every atom and every bond in a molecule
Define structural formula
Define structural formula
Shows arrangement of atoms in a molecule without showing every bond
Define skeletal formula
Define skeletal formula
Drawn as lines with each vertex being a carbon atom. Carbon atoms not drawn, assumed each C atom has all unspecified bonds as C-H
Give the prefixes for: Give the prefixes for:
a) CH3 group
b) C2H5 group
c) C3H7 group
d) C4H9 group
e) Cl group
f) Br group
g) I group
Give the prefixes for:
a) CH3 group methyl-
b) C2H5 group ethyl-
c) C3H7 group propyl-
d) C4H9 group butyl-
e) Cl group chloro-
f) Br group bromo-
g) I group iodo-
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What is functional group isomerism?
What is functional group isomerism?
Same atoms but a different functional group due to a different arrangement of atoms
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What is chain isomerism?
What is chain isomerism?
Hydrocarbon chain organised differently e.g. branched chains
Define stereoisomerism.
Define stereoisomerism.
When molecules have the same structural and molecular formula, but have a different arrangement of atoms in space
What is E-Z isomerism and how are the E and Z isomers decided?
What is E-Z isomerism and how are the E and Z isomers decided?
E-Z isomerism is caused by the limited rotation about C=C double bonds
If the two substituents with the highest molecular mass are on the same side of the double bond, it is the Z (zusammen) isomer
If they are on different sides, it is the E (entgegen) isomer
What is an alkane?
What is an alkane?
A saturated hydrocarbons containing C-H bonds only
Are their bonds polar? Why/why not?
Are their bonds polar? Why/why not?
Nonpolar- carbon and hydrogen have similar electronegativities
Intermolecular forces? Why?
Intermolecular forces? Why?
Only van der Waals forces of attraction - bonds are non-polar
Solubility in water? why?
Solubility in water? why?
Insoluble because hydrogen bonds in water are stronger than alkanes’ van der Waals forces of attraction
How reactive are alkanes?
How reactive are alkanes?
Very unreactive
Which reactions will alkanes undergo?
Which reactions will alkanes undergo?
Combustion and reaction with halogens
What is crude oil? How is it formed? Is it renewable? Why?
What is crude oil? How is it formed? Is it renewable? Why?
Mixture of fractions (hydrocarbons with similar boiling points and properties)
Formed at high temperatures and pressures deep below earth’s surface over millions of years → therefore non-renewable
Name the fractions from high to low boiling point.
Name the fractions from low to high boiling point.
Gases - fuel on site Gasoline/petrol/naphtha - cars Kerosene/paraffin - jet fuel, lighting Diesel oil - lorries/taxis
Lubricating oil/waxes - candles, engine oil Fuel oil - ships, power stations Tar/bitumen - roads/roofing
What is fractional distillation/how does it work?
What is fractional distillation/how does it work?
Crude oil heated until mostly vapourised
Passed into a fractionating tower that is cooler at the top than the bottom Liquid fractions are piped off at the bottom
Vapours rise up the column and - via trays and bubble caps - condense when temperature < their boiling point
Shortest chain hydrocarbons condense at the top as they have the lowest boiling points
What is fracking and how is it done?
What is fracking and how is it done?
Natural gas held within shale rock
Drill into shale, force pressurised water and sand into rock to fracture it, Collect gas
HCl and methanol added to break up shale and prevent corrosion
Pros/cons of fracking?
Pros/cons of fracking?
Advantages - gas supply for many years, reduces imported gas and electricity
Disadvantages - lots of traffic to local area, concern about amount of water used, chemical additives can pollute water supplies, can cause small earthquakes, combust CH4 → CO2 → global warming
Why are alkanes cracked?
Why are alkanes cracked?
To turn a long chain alkane, with is not very economically valuable, into a shorter chain alkane (more economically valuable as can be used as a fuel) and an alkene (more reactive, starting point for many products)
What are the conditions for thermal cracking?
What are the conditions for thermal cracking?
700-1200 K temperature Up to 7000 kPa pressure
What is the intermediate for the reaction?
What is the intermediate for the reaction?
Free radicals
What r the main products of thermal cracking
Alkenes
What are the conditions for catalytic cracking?
What are the conditions for catalytic cracking? Lower temp (720K) Lower pressure (but above atmospheric) Zeolite catalyst (SiO2 and Al2O3) with a honeycomb structure to give a large surface area
What are the main products of catalytic cracking?
What are the main products of catalytic cracking?
Cycloalkanes, aromatic hydrocarbons, branched alkanes
Write an equation for the combustion of propane
Write an equation for the combustion of propane
C3H8 + 5O2 → 3CO2 + 4H2O
What is a feul
Sumn which releases heat energy when combusted
What are the five main fuels comprising of alkanes?
What are the five main fuels comprising of alkanes?
Methane, butane, propane, petrol (about C8), paraffin (C10 - C18)
What is incomplete combustion and what products are formed in the case of alkanes?
What is incomplete combustion and what products are formed in the case of alkanes?
Combustion in a limited supply of oxygen
CO - carbon monoxide - poisonous
C - carbon - particulates - soot - global dimming
What is the environmental impact of carbon monoxide?
It is toxic/poisonous
What is the environmental impact of carbon monoxide?
It is toxic/poisonous
Which type of hydrocarbons are most likely to undergo incomplete combustion?
Longer chains
What is the environmental impact of sulfur impurities/sulfur dioxide
What is the environmental impact of sulfur impurities/ sulfur dioxide?
form sulphuric acid → acid rain
What is the environmental impact of soot (carbon)?
What is the environmental impact of soot (carbon)?
asthma, cancer, global dimming
What is the environmental impact of unburnt hydrocarbons?
What is the environmental impact of unburnt hydrocarbons?
Photochemical smog
What is the environmental impact of carbon dioxide?
What is the environmental impact of carbon dioxide?
greenhouse gas → global warming, increases global temperatures, speeds up climate change
What is the environmental impact of water vapour?
What is the environmental impact of water vapour?
greenhouse gas → global warming, increases global temperatures, speeds up climate change
What r flue gases
Gases given out by power stations
Write two equations for two different ways of desulfurising flue gases.
Write two equations for two different ways of desulfurising flue gases.
CaO (s) + 2H2O (l) + SO2 (g) + 1⁄2O2 (g) → CaSO4.2H2O (s)
Or
CaCO3 (s) + SO2 (g) + 1⁄2O2 (g) → CaSO4+ CO2 (g)
What are catalytic converters made up of?
What are catalytic converters made up of?
Ceramic honeycomb coated with platinum, palladium and rhodium (Pt, Pd and Rh) metals
What do catalytic converters catalyse (equations)?
What do catalytic converters catalyse (equations)?
They catalyse these reactions of products from car exhausts:
2CO (g) + 2NO (g) → N2 (g) + 2CO2 (g)
Hydrocarbons + NO → N2 + CO2 + H2O
What are greenhouse gases
What are greenhouse gases?
Gases which trap infrared radiation, making the earth act like a greenhouse
What is the greenhouse effect and how does it contribute to global warming?
What is the greenhouse effect and how does it contribute to global warming?
Greenhouse gases trap infrared radiation in the atmosphere, atmosphere heats up → global warming
Define carbon neutral activities
Define carbon neutral activities
Activities that produce no net / overall carbon dioxide emissions
How are halogenoalkanes formed from alkanes?
How are halogenoalkanes formed from alkanes?
Free radical substitution reaction
What are the three stages of free radical substitution?
What are the three stages of free radical substitution?
Initiation - breaking halogen bond to form free radicals Propagation - chain part of the reaction where products are formed but free radical remains
Termination - free radicals removed, stable products formed
What are the conditions needed for the formation of a free radical chlorine atom?
What are the conditions needed for the formation of a free radical chlorine atom?
Presence of UV light
Write equations for the reaction of CH4 with Cl2 to form CH3Cl
Initiation: Cl2 → 2Cl• (in presence of UV light)
Propagation:
Cl• + CH4 → HCl + •CH3
•CH3 + Cl2 → CH3Cl + Cl•
Termination:
•CH3 + Cl• → CH3Cl 2Cl• → Cl2
•CH3+ •CH3→ CH3CH3
What is the ozone layer’s function?
What is the ozone layer’s function?
protects the earth from harmful exposure to too many UV rays
How do CFCs break the ozone layer down?
How do CFCs break the ozone layer down?
Free radical substitution
Write an equation for the overall decomposition of ozone into oxygen (O2)
Write an equation for the overall decomposition of ozone into oxygen (O2)
2O3→ 3O2
Write free radical substitution equations to show how Cl free radicals catalyse the decomposition of o3
Write free radical substitution equations to show how Cl free radicals catalyse the decomposition of O3
Cl2 → 2Cl• (in presence of UV light) Cl• + O3→ ClO• + O2
ClO• + O3 → 2O2 + Cl•
Overall: 2O3→ 3O2
Are halogenoalkanes soluble in water?
Are halogenoalkanes soluble in water?
Insoluble as C-H bonds are non-polar, not compensated for enough by C-X bond polarity
Do halogenoalkanes have a polar bond? why?
Do halogenoalkanes have a polar bond? why?
Yes polar, as halogen has a higher electronegativity than C ( halogen is δ-, carbon is δ+)
Which intermolecular forces do they have? Why?
Which intermolecular forces do they have? why?
Permanent dipole-dipole and van der Waals forces of attraction
C-X bond polarity creates permanent dipoles
When would Halogenoalkanes have higher boiling points
When would they have higher boiling points?
Increase Carbon chain length Halogen further down group 7
How would the mass of a haloalkane compare with the mass of an alkane of the same chain length?
Greater as mass of halogen > mass of H
What is the most important factor in determining their their reactivity
Carbon halogen bond enthalpy
What would bond polarity suggest the order of reactivity would be?
What would bond polarity suggest the order of reactivity would be?
C-F would be most reactive as most polar bond
What would bond enthalpies suggest the order of reactivity would be?
What would bond enthalpies suggest the order of reactivity would be?
C-I would be most reactive as lowest bond enthalpy
What is a nucleophile?
What is a nucleophile?
A negatively charged ion/δ− atom with a lone pair of electrons which can be donated to an electron deficient atom
Give 3 examples of nucleophiles
Give 3 examples of nucleophiles
:OH- :CN- :NH3
What is nucleophilic substitution?
What is nucleophilic substitution?
A reaction where a nucleophile donates a lone pair of electrons to δ+ C atom, δ− atom leaves molecule (replaced by nucleophiles)
Draw the mechanism for the reaction of bromoethane with NaOH (aq).
Draw the mechanism for the reaction of bromoethane with NaOH (aq).
Draw the mechanism for the reaction of bromoethane with KCN
Draw the mechanism for the reaction of bromoethane with KCN
Draw the mechanism for the reaction of bromoethane with NH3
Draw the mechanism for the reaction of bromoethane with NH3
Draw a mechanism for the reaction of bromoethane with NaOH in ethanol
Draw a mechanism for the reaction of bromoethane with NaOH in ethanol
What are CFCs?
What are CFCs?
Chlorine-fluoro-carbons - haloalkanes containing C, F and Cl only (no H)
What is the problem with CFCs?
What is the problem with CFCs?
Although unreactive under normal conditions, they catalyse the breakdown of ozone in the atmosphere via free radical substitution
What are CFCs being replaced with?
What are CFCs being replaced with?
HCFCs (hydrogen, chlorine, fluorine, carbon) HFCs (hydrogen, fluorine, carbon)
What are the conditions/reactants needed for the elimination reaction of haloalkanes?
What are the conditions/reactants needed for the elimination reaction of haloalkanes?
NaOH or KOH dissolved in ethanol (no water present)
Heated
What is formed in the elimination reaction of haloalkanes?
What is formed in the elimination reaction of haloalkanes?
An alkene, water and halogen ion
What is an alkene
What is an alkene?
Unsaturated hydrocarbons with a C=C double bond
What is the general formula of an alkene and alkane
CnH2n
CnH2n+2
Why is there no rotation about the C=C double bond?
Why is there no rotation about the C=C double bond?
Due to the π (pi) orbital - electron density above and below the single bond, which holds the carbon atoms in place
Are they more or less reactive than alkanes? Why?
Are they more or less reactive than alkanes? Why?
More reactive, due to high electron density of double bond and the fact the pi-bond is slightly easier to break
What intermolecular forces of attraction do they have?
What intermolecular forces of attraction do they have?
Only van der Waals due to non-polar bonds
Are they soluble in water? Why?
Are they soluble in water? Why?
No, non-polar bonds (van der Waals’ < hydrogen bonding)
Name and describe the three kinds of isomers alkenes can have
Name and describe the three kinds of isomers alkenes can have Chain isomers (branched chains) Position isomers (C=C on different carbon atom) Geometric E-Z isomers (Z is when 2 highest atomic number chains are on the same side of the double bond; E is when they're on opposite sides)
Write an equation for the complete combustion of pent-2-ene
Write an equation for the complete combustion of pent-2-ene.
CH3CH=CHCH2CH3 + 71⁄2O2 → 5CO2 + 5H2O
What is an elecrophile
What is an electrophile?
Electron deficient atoms/ions which accept a pair of electrons (here, from the C=C double bond)
What is the most stable kind of carbocation intermediate? Why?
What is the most stable kind of carbocation intermediate? Why?
Alkyl groups have a positive inductive effect, so the most stable carbonation is the one bonded to the most other carbon atoms i.e. A tertiary carbocation
Major products will be formed from which kinds of carbocations?
Major products will be formed from which kinds of carbocations?
Tertiary (or the most stable avaliable)
What conditions are needed for the electrophilic addition of H2O to an alkene?
What conditions are needed for the electrophilic addition of H2O to an alkene?
Acid catalyst, usually phosphoric acid
What are the product(s) of the reaction?
An alcohol
Draw a mechanism for the addition of water to ethene
Draw a mechanism for the addition of water to ethene
What conditions are needed for the electrophilic addition of a hydrogen halide to an alkene?
Room temperature
Draw a mechanism for the reaction of HBr and ethene.
Draw a mechanism for the reaction of HBr and ethene.
What conditions are needed for the electrophilic addition of a halogen molecule to an alkene?
What conditions are needed for the electrophilic addition of a halogen molecule to an alkene?
Room temperature and organic solvent
How does a molecule with a non-polar bond react as if it is an electrophile?
How does a molecule with a non-polar bond react as if it is an electrophile?
C=C double bond with a high electron density induces a temporary dipole in the halogen molecule → δ+ atom attracted to double bond
Draw a mechanism for the reaction between bromine and ethene
Draw a mechanism for the reaction between bromine and ethene
Draw a mechanism for the reaction of sulfuric acid with ethene.
Draw a mechanism for the reaction of sulfuric acid with ethene.
How would you turn the product into an alcohol and how does show that sulfuric acid catalyses the addition of water to an alkene?
How would you turn the product into an alcohol and how does show that sulfuric acid catalyses the addition of water to an alkene?
Add water
H2SO4 reforms, showing it catalyses the hydration of alkenes
What is an addition polymer?
What is an addition polymer?
many monomers bonded together via rearrangement of bonds without the loss of any atom or molecule
What are monomers? What form do they usually take?
What are monomers? What form do they usually take?
Molecules which combine to form a polymer Usually have a C=C bond which breaks to leave a repeating pattern
Draw how you would represent the polymerisation of
ethene.
Draw how you would represent the polymerisation of
ethene.
Give 3 uses of poly(chloroethene) / PVC
Give 3 uses of poly(chloroethene) / PVC
Drainpipes Vinyl Aprons
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