Organic Chemistry 1 Flashcards
Define “Hydrocarbon”
A compound of carbon and hydrogen only.
Define “Homologous Series”
Series of organic compounds with the same functional group and general formula. Each successive members physical and chemical properties follow a trend.
Define “Functional Group”
A group of atoms responsible for the characteristic reactions of a particular compound.
Define Isomerism
Same molecular formula but different arrangement of their atoms.
Define Structural Isomerism and describe the 3 different types
Structural Isomerism - Atoms are bonded in a different order
* Chain Isomerism - different arrangement of molecules in the carbon skeleton
* Position Isomerism - Differing position of the same functional group in a molecule
* Functional Isomerism - Different positions of atoms give a different functional group
Explain why boiling points increase as alkanes get bigger
Carbon Chain increases as molecule gets bigger
More electrons present which can induce each other
Greater London forces
Explain the affect of branching on alkanes
Branching decreases surface area between the molecules
Decreasing the London forces as molecules cant get anymore compact(close)
Decreases the boiling point
State the General Formula for Alkanes
CnH2n+2
What are the byproducts for the complete combustion of an Alkane or Alkene?
Carbon dioxide and water.
What are the byproducts for the incomplete combustion of an Alkane or Alkene?
Carbon monoxide and water.
Describe how CO2 is formed and its problems/solutions
*Complete Combustion
*Problem - its a greenhouse gas causing global warming leading to climate change
*Solution - burn less fossil fuels
Describe how CO is formed and its problems/solutions
*Incomplete Combustion
*Problem - toxic gas(binds to red blood cells) causing strain on the heart
*Solution - ensure good supply of air/;oxygen when burning
Describe how Carbon particles are formed and its problems/solutions
*Incomplete Combustion
*Problem - blackens buildings and global dimming
*Solution - particulate filter in engines which catches particles then are burnt
Describe how SO2 is formed and its problems/solutions
*Crude Oil and combustion of sulphur
*Problem - acid rain
*Solution - remove Sulphur from fuel before it is burnt or remove SO2 from fumes after it is burnt(flue gas desulfurization)
Describe how Nitrogen oxides are formed and its problems/solutions
*Reaction with Nitrogen in the air at very high temperatures(often in engines or furnaces)
*Problem - acid rain
*Solution - Catalytic Converter
Describe how Nitrogen oxides are formed and its problems/solutions
*Not all fuel burns
*Problem - Waste fuel and harmful greenhouse gases
*Solution - ensure correct air mixture when fuel is burned
Explain why Alkanes are relatively unreactive
*Saturated hydrocarbons
*Non-polar
State the two types of reactions with a Alkane
*Combustion
- (Overall) Alkane +Oxygen ¬¬> Carbon Dioxide + Water
*Radical Substitution
* * - Alkane + Halogen –> Halogenoalkane + (Overall)Hydrogen Halide
Define Radical
Radicals are particles that have unpaired electrons meaning they are very reactive(represented by a dot).
Formed during Homolytic fission when the bond breaks evenly producing two uncharged radicals.
State two conditions needed for an Alkane to react
Ultraviolet light or high temperatures due to lots of energy needed to break the bond
State the three stages of Radical Substitution reaction
- Initiation
- Propagation
- Termination
Describe ways Alkane fuels are obtained in crude oil
Fractional Distillation(different length hydrocarbons are produced in different fractions once heated)
Cracking (turning long chain hydrocarbons into shorter ones)
Reforming Crude Oil (turning straight line alkanes into branched or cylicalkanes for efficient combustion)
Describes the limits of Radical Substitution Reactions
Radicals are very reactive and can react with any of the carbons on the carbon chain.
A mixture of products can form if theres too much of one radical causing a chain reaction.
Alkanes and Alkenes are what type of hydrocarbons
Alkanes - Saturated
Alkenes- Unsaturated
State the General Formula for Alkenes
CnH2n
Describe bonding in alkenes in terms of pi and sigma bonding
The Double bond is made up of one sigma bond and one pi bond
Sigma side-to-side bonding and 2 pi bonds over the top in Ethene
Define an ‘electrophile’
A species which is partially positive charge that is attracted to an area of negative charge and can accept a pair of electrons
What are the products of the Hydrogenation of an Alkene and why is it important
Hydrogen + Alkene makes an Alkane
Nickel Catalyst at 150*C
This is used in the manufacture of margarine of unsaturated vegetable oils.
What reaction makes Halogenoalkanes from Alkenes(mention the difference)
Electrophilic addition:
Hydrogen Halide - Halogenoalkane
Halogen - dihalogenoalkanes
Describe how to make a Alcohol from an Alkene
Steam
Acid catalyst (phosphoric acid)
Describe how to make Diol
Potassium manganate(VII), in acid conditions
Describe ‘Heterolytic Fission’
Bond breaks unevenly forming two ions.
One bonding atoms receives both electrons from the bonding pair.
Describe the qualitative test from C=C bond
Bromine water goes brown to colourless in a presence of an alkene.
What are the three different ways waste polymers can be sepearated
- Recycling
- Incineration to release energy
- Use as a feedstock for cracking
What are two ways chemist limit problems caused by polymer disposal
- Biodegradable polymers
- Removing toxic waste gases caused by incineration of plastics
What’s the difference between Primary/Secondary/Tertiary Halogenoalkanes
Primary - Halogen is on the end of the carbon chain
Secondary - Halogen is in the middle of the carbon chain
Tertiary - Halogen is in the middle of the carbon chain connected to a methyl group
Define ‘Nucleophile’
A species that can donate a pair of electrons to make a covalent bond.
How do you make a Alcohol from an Halogenoalkane
Aqueous Potassium hydroxide
Nucleophile - Hydroxide Ion
What happens when you add aqueous silver nitrate solution in ethanol with an halogenoalkane
The water molecules and the halogenoalkane react to form an alcohol(nucleophilic substitution)
The halide ion and the silver nitrate react to form silver halide which is insoluble- Precipitate Reaction
Ethanol is to dissolve the halogenoalkane and water
How do you produce a Nitrile from a halogenoalkane
Potassium cyanide under reflux
Nucleophile - Cyanide ions
How do you produce an Amine from a Halogenoalkane
Ammonia
Nucleophile - Ammonia molecule
What is an addition reaction
Addition reaction occurs when two or more reactants combine to form a single product. This product will contain all the atoms that were present in the reactants. Addition reactions occur with unsaturated compounds.
What is an elimination reaction
An elimination reaction occurs when a reactant is broken up into two products. Elimination reactions occur with saturated compounds
What is an substitution reaction
A substitution reaction occurs when an exchange of elements in the reactants takes place. The initial reactants are transformed or swopped around to give a final product.
What is a hydrolysis reaction
Splitting a molecule into two new molecules by adding H+ and OH– derived from water. This reaction occurs mainly in polymers that take up a lot of moisture and that have water-sensitive groups in the polymer backbone.
What is polymerisation?
The process of making polymers(long chained molecules) through the addition of monomers joining together
Define ‘Stereoisomerism’
Compounds with the same structural formula but with a different arrangement in space
Define ‘Structural Isomerism’
Compounds with the same molecular formula but with a different structural formula
What are the three colours of the silver halide precipitates?
Silver chloride - white
Silver bromide - cream
Silver iodide - Yellow
What is special about producing a Nitrile from a halogenoalkane
It increases the length of the carbon chain
Which halogenoalkane is the most reactive(chloro,bromo,iodo)?
Iodoalkane - takes the shortest time and chloro is the longest
Carbon - Iodide is the weakest bond enthalpy
Less energy required to break
Which halogenoalkane is the most reactive(primary,secondary,tertiary)?
Tertiary - takes the shortest time and primary is the longest time
*It is more difficult to explain the reason for this, because it needs a fairly intimate knowledge of the mechanisms involved in the reactions. It reflects the change in the way that the halide ion is produced as you go from primary to secondary to tertiary halogenoalkanes.
How do you produce an Alkene from an Halogenoalkane?
Ethanoic Potassium Hydroxide
Elimination Reaction
Base - hydroxide ion
How do you form a ketone from an Alcohol?
Formed from Secondary Alcohols only
Potassium dichromate(VI) in dilute sulfuric acid
Distillation/Under Reflux
How do you form an Aldehyde from an Alcohol?
Formed from Primary Alcohols
Potassium dichromate(VI) in dilute sulfuric acid
Distillation(partial oxidation)
How do you form an carboxylic acid from an Alcohol?
Formed from Primary Alcohols
Potassium dichromate(VI) in dilute sulfuric acid
Heated Under Reflux(fully oxidised)
How do you test for an Aldehyde?
Fehlings/Benedicts solution
-turns blue to brick red
How do you form an Alkene from an Alcohol?
Conc Phosphoric Acid
How do you produce a chloroalkane from an alcohol?
PCl5(Primary/Secondary) or HCl(tertiary)
How do you produce a bromoalkane from an alcohol?
KBr
50% conc sulphuric acid
How do you produce a iodoalkane from an alcohol?
P4(red phosphorus)
Name 3 drying agents
Calcium Chloride
Magnesium Sulphate
Sodium Sulphate
Describe the use of a separating funnel
- Denser solution settles in the bottom of the funnel then is drain off
Describe distillation technique
Thermometer should be in the ‘entrance’ of the condenser tube
Water in from the bottom and water out at the top for more efficient cooling system
Ice water mixture to condense the products
Add antibumping granules to avoid large bubbles forming
Describe heated under reflux
No gaps in between pear shape flask and condenser
Dont cover the top of the condenser
