Organic chem - 1 Flashcards
Define organic chemistry
Organic chemistry is the study of carbon based compounds.
Why is organic chemistry very important?
Industrially, produces billions of euro, necessary for the production of pharmaceuticals, petrol, diesel etc.
Name the three important homologous series
- Alkanes
- Alkenes
- Alkynes
How many bonds can carbon form?
4 because it has a valency of 4 & is in group 4
What can carbon bonds comprise of?
a) . 4 single bonds - saturated. (4 bonding pairs; no lone pairs - tetrahedral)
b) . 1 double bond & 2 single bonds - unsaturated. (3 bonding pairs; no lone pairs - planar)
c) . 1 triple bond & 1 single bond - unsaturated. (2 bonding pairs; no lone pairs - planar)
Define saturated
Contains only single bonds around carbon atoms.
Define unsaturated
Contains a multiple bond between two carbon atoms.
Define hydrocarbon
A hydrocarbon is a compound that consists of the elements carbon and hydrogen.
What are hydrocarbons formed by?
Formed by the decomposition of animal waste and vegetation.
Define aliphatic hydrocarbons
Aliphatic hydrocarbons are straight or branched-chained hydrocarbon molecules.
Define aromatic hydrocarbons
Aromatic hydrocarbons are hydrocarbons that contain a ‘ring’ in their structure i.e a benzene ring.
Name 3 sources of hydrocarbons
- Coal
- Natural gas (methane)
- Petroleum (crude oil)
Describe coal as a hydrocarbon
- Coal is a black solid that contains mainly carbon.
- Burning coal causes air pollution.
Describe natural gas (methane) as a hydrocarbon
- It is produced when dead organic material is converted into hydrocarbon molecules over millions of years.
- Found in slurry pits , coal mines, intestinal bacteria of cows and sheep and rubbish dumps.
- Kinsale gas = 95% methane which contributes to the greenhouse effect.
Describe crude oil as a hydrocarbon
- Consists of many aliphatic and aromatic hydrocarbons.
Used to make drugs, plastics, cosmetics, petrol etc.
Most sought after resource.
Thick black substance - but useless in that form.
What is the biggest source of hydrocarbons?
Petroleum (crude oil)
What are hydrocarbons
Fuels i.e they release energy when burned in oxygen.
What is the number of carbons in ‘Meth’
1
What is the number of carbons in ‘Eth’
2
What is the number of carbons in ‘Prop’
3
What is the number of carbons in ‘But’
4
What is the number of carbons in ‘Pent’
5
What is the number of carbons in ‘Hex’
6
What is the number of carbons in ‘Hept’
7
What is the number of carbons in ‘Oct’
8
What type of bonds do alkanes have around/between them?
Single bonds around/between the carbon atoms
Are alkanes saturated or unsaturated compounds?
Saturated compounds
What do the names of alkane molecules end in
- ane i.e methane, ethane, propane
What are C1-C4 at room temperature?
Gases
What are C5-C16 at room temperature?
Liquids
What are C17 + at room temperature?
Waxy solids
What force of attraction do Alkanes have?
Weak Van der Waals forces of attraction
Why/When does the boiling point increase
With increasing chain length as greater surface contact between molecules means greater numbers of Van der Waals forces between the molecules.
What does each successive member of the alkanes differ by?
CH₂
Are alkanes soluble or insoluble in water?
Insoluble
Why are alkanes insoluble in water?
As they are non-polar molecules (tetrahedral shape) and do not form hydrogen bonds with water.
Are alkanes soluble or insoluble in non-polar solvents such as cyclohexane or chloroform?
Soluble
Why is ethane a good fuel?
As it is unreactive (unreactive because of the fact that they are saturated)
What are the two diagnostic tests proving that alkanes are saturated compounds?
- saturated -> unreactive, alkanes do not decolourise bromine water from red/brown to colourless or a dilute solution of potassium manganate (VII) from purple to colourless.
What type of reactions do alkanes usually undergo?
Free radical substitution
What is free radical substitution?
When an atom or group of atoms are replaced by another atom or group of atoms. Two main products are produced, one organic and one inorganic.
What is an organic compound?
Any large class of chemical compounds in which one or more atoms of carbon are covalently linked to atoms of other elements, most commonly H, O or N.
In the combustion : CH4 +Cl2 –> CH3Cl + HCl , what is the re-agent , the condition and the organic product
- re-agent = Cl
- the condition = uv light
- organic product = cloro methane
What are conditions?
Conditions are things that need to be present for a reaction to happen.
Can every organic molecule undergo combustion?
Yes
What shape are all alkanes?
Tetrahedral
Why are all alkanes tetrahedral?
Due to the presence of four bonding pairs and no lone pairs around the carbon atom.
What are the 4 IUPAC system rules?
- The longest chain carbon is the parent alkane.
- The alkane is named from whichever direction gives the lowest number to the carbon atom to which the groups are attached.
- The substituted groups are then named and numbered alphabetically i.e bromo before chloro, ethyl before methyl etc.
- If there are two of the same group on the molecule then the prefix ‘di’ is placed before the groups name i.e dimethyl. If there are three of the same group then ‘tri’ is used and four, tetra.
What is the combustion of methane?
Ch4 + 2O₂ –> CO₂ +2H₂O
What is the combustion of Ethanol?
C₂H5OH +3O2 –> 2CO₂ +3H₂O
What is the combustion of propanoic acid?
C₂H5COOH + 3.5O₂ –> 3CO₂ +3H₂O
What is the combustion formula?
Organic compound + O₂ –> CO₂ + H₂0 + energy
What are alkyl groups?
The alkane missing one of its hydrogens
Name 2 alkyl groups?
CH₃ - Methyl
C₂H5 - Ethyl
What happens if you put an alkyl group on the first carbon of a molecule?
It is simply an extension of the chain.
What do you get if you put a methyl group on the first carbon of propane ?
You get butane
Does 1-methylpropane exist?
NO - its butane
Define structural isomers
Structural isomers are molecules with the same molecular formulas but different structural formulas. (Different names but the same number and type of atoms)
How many isomers of C5H12 are there? Give there names and structural formulae.
3 isomers:
- Pentane
- 2 methylbutane
- 2,2 dimethylpropane
Define a homologous series
A homologous series is a group of compounds, all members of the group contain the same functional group and successive members differ by CH2.
Define a functional group
A functional group is a group of atoms upon which the characteristic properties of a homologous series depends.
What type of bonds are between alkenes?
All members of alkenes contain one double bond between two of the carbon atoms.
Are alkenes saturated or unsaturated?
Unsaturated
Why are alkenes unsaturated?
They are unsaturated as they contain a multiple bond between two carbon atoms.
(alkenes) C2 –> C4 are …..
Gases
(alkenes) C5 –> C16 are ……..
Liquids