Organic Chemistry Flashcards
What is crude oil?
1) A finite resource found in rocks
2) the remains of an ancient biomass consisting mainly of plankton that was buried in mud
3) mixture of a a large number of compounds, most of them being hydrocarbons
Most of the hydrocarbons in crude oil are called…
Alkanes
What is the the general alkane formula?
C2H2n+2
Alkanes are:
1) a homologous series
2) saturated compounds
3) they all have C-C single bonds
The shorter the carbon chain
1) The less viscous (more runny)
2) more volatile (lower bp)
3) the more flammable
Complete combustion of hydrocarbons
1) happens when there’s plenty of oxygen
2) releases a lot of energy, carbon dioxide and water
3) carbon and hydrogen are oxidised
Fractional distillation
1) oil is heated until it is mostly gas
2) gases enter a fractionating column (liquid is drained off)
3) in columns here’s a temp gradient (gets cooler as you go up)
4) longer hydrocarbons have higher bp, condense back and drain out the column early on
5) the shorter hydrocarbons have lower bp, condense near the top of column when it’s cooler.
7) end up with crude oil mixture separated into different fractions
What can the fractions of crude oil be used for?
To produce fuels and feedstock for the petrochemical industry
What useful materials are made by the petrochemical industry?
Solvents, polymers, detergents, lubricants
What fuels can you make from fractional distillation?
Diesel, kerosene, petrol, LPG
Two forms of cracking?
1) Catalytic cracking (400C, high pressure?)
2) steam cracking (600C, low pressure?)
Alkanes are…
1) Hydrocarbons with a double C=C bond
The homologous series for alkenes is…
CnH2n
Why are alkenes unsaturated?
Because they have two fewer hydrogen atoms than alkanes with the same number of carbon
How do alkenes react with oxygen?
In the same way as other hydrocarbons (combustion reaction) but it tends to burn in a smoky flame due to incomplete combustion
What is alcohol’s functional group?
-OH
When an alcohol reacts with sodium…
One of their products is hydrogen
When reacting with oxygen, alcohols…
Oxidise to create carboxylic acid eg methanoic acid
Why are alcohols used as solvents?
Bc they can dissolve most things water can dissolve but can also dissolve things water can’t eg hydrocarbons, fats and oils
Shy are alcohols used as fuels?
Eg ethanol is used as a fuel In spirit burners. Burns fairly cleanly and non smelly
How can ethanol be made?
Fermentation. This process uses an enzyme from yeast to convert sugars into ethanol. CO2 is also produced.
Fermentation happens fastest at
37 degrees in slightly acidic solution and under anaerobic conditions
What’s the functional group for carboxylic acids?
-COOH
What happens when carboxylic acids react with carbonates?
Produce a salt, water and co2. Salts would end in -anoate eg ethanoate.
Carboxylic acid can’t/ can dissolve in water?
CAN. They ionise and release H+ ions resulting in an acidic solution. But they only form weak acidic solutions because not all acid molecules release their h+ ions, meaning they have a higher pH than aqueous solutions of strong acids with the same concentration.
Eaters have functional group…
-COO- and are formed from an alcohol and a carboxylic acid. An acid catalyst is usually used
Alkenes can be used to produce polymers eg poly(ethene) through…
Addition polymerisation
What happens during addition polymerisation reactions?
Many small monomers join together to form very large molecules aka polymers. Requires a catalyst and high pressure
Condensation polymerisation involves…
Monomers with two functional groups.
During c.p., monomers that react and join together…
Lose small molecules such as water
How many functional groups do amino acids have?
Two
How do amino acids react?
Through c.p. to produce polypeptides. Amino acids can be combined in the same chain to produce proteins
What are DNA molecules made from?
Hey are two polymer chains, made from four different monomers called nucleotides in the form of a double helix
