7-Organic Chemistry (2) Flashcards
1
Q
What are hydrocarbons?
A
compounds that contain hydrogen and carbon only
2
Q
2What are Alkanes?
A
- simplist type of hydrocarbon
- CnH2n+2
- homologous series - all react in a similar way
- saturated compounds, each carbon atom forms four single covalent bonds
- first four alkanes methane CH4, ethane C2H6, propane C3H8, butane C4H10
3
Q
What are short chain hydrocarbon’s like?
A
- more runny, less viscous
- more volatile, lower boiling point - more flammable - used for fuels
4
Q
What is complete combustion?
A
- burning of hydrocarbon’s with pleanty of oxygen
- hydrogen + oxygen -> carbon dioxide + water
5
Q
What is crude oil?
A
- remains of animals and plants, mainly plankton
- can be drilled up from rocks and seperated into useful oils through fractional distillation
6
Q
How does fractional distillation work?
A
- heated till most turned into gas then put into fractioning collumn
- hot at bottom of column and cooler as you go up - temperature gradient
- longer hydrocarbons have higher boiling points and shorter have lower, so condense into liquids and drain out earlier on
- longer condense into liquids higher up the column
- crude oil mixture seperated into useful products
7
Q
What are the uses of crude oil?
A
- fuel for transport
- some used as feedstock to make new compounds for use in polymers, solvents, lubricants, detergents
8
Q
What is cracking?
A
- splitting up of long chain hydrocarbonds to make shorter, more useful ones
- cracking produces alkenes aswell
- some products of cracking used as fuel
9
Q
What are the different methods of cracking?
A
- Thermal decomposition - breaking molecules down by heating them, first vapourised then passed over hot powdered aluminium oxide catalyst and long - chain molecules split apart - catalyctic cracking
- Vaporise and mix with steam and heat to very high temperatures - steam cracking
10
Q
What are alkenes?
A
- double C bond - unsaturated hydrocarbons, open up to form single bons - highly reactive
- Ethene C2H4, Propene C3H6, Butene C4H8, Pentene C5H10
- formula CnH2n
11
Q
What is incomplete combustion of Alkene’s like?
A
- results in smoky yellow flame and less energy
- alkene + oxygen -> carbon + carbon monoxide + carbon dioxide + water
12
Q
How do Alkene’s react?
A
- addition reactions
- all react in similar ways as in the same functional group
- carbon double bond opens up to a single bond and a new atom added to each carbon
13
Q
What is hydrogenation?
A
- addition of hydrogen to Alkanes
- double bond carbon’s open up
- alkene reacted with hydrogen in the pressure of catalyst
14
Q
How are alcohols formed from alkenes?
A
- when alkenes react with steam and water added across double bond
- ethanol made by mixing ethene with steam and passing over catalyst
15
Q
How do the halogens react with Alkenes?
A
- Alkenes react in adition reactions with halogens such as bromine, chlorine, and iodine
- form saturated molecules with C=C carbon each becoming bonded to a halogen atom
- e.g bromine and ethene react to form dibromoethane
16
Q
How do you test for alkenes?
A
- add bromine water and shake - goes colourless
17
Q
What are Alcohols like?
A
- general formula CnH2n+1OH
- alcohols flammable
- undergo complete combustion in air produce carbon dioxide and water
- can be made by fermentation - sugar (yeast ->) ethanol +carbon dioxide
18
Q
What are carboxylic acids like?
A
- functional group -COOH
- names end in -anoic acid
- react like other acids but salts end in -anoate e.g ethanoate
- can dissolve in water and ionise to release H+ ions, don’t completely ionise
19
Q
How can esters be made?
A
- from an alcohol and carboxylic acids
- functional group -COO
- acidic catalyst usually used
- alcohol + carboxylic acid -> ester + water
20
Q
What is condensation polymerisation?
A
- making polymers using monomers from different functional groups
- monomers react together and bond forms between them to make polymer chains
- for each new bond that forms, a small molecule, e.g water is lost
21
Q
How are addition and condensation polymerisation different?
A
- addition contains 1 monomer type and C=C bond whereas condensation involves 2 monomer types each containing 2 of the same functional groups or 1 monomer type with 2 different functional groups
- addition forms 1 product, condensation forms 2 types of products, polymer and small molecule
- addition produces carbon-cabron double bond in monomer, condensation has two reactive groups on each monomer
22
Q
What are some examples of naturally occuring polymers?
A
- Proteins - polymers of amino acids
- DNA made form nucleotide polymers
- simple sugars can form polymers
