Organic Chem Flashcards
What does the displayed formula show?
Shows the spatial arrangement of all the atoms/bonds in a molecule.
What does the structural formula show?
Unambiguous description of the way atoms in a molecule are arranged. Usually only show double/tripile bonds. Single bonds are omitted.
What are structural isomers?
Compounds that have the same molecular formula but different structural formula.
4 Things a homologous series have in common:
- Same general formula
- Same functional group
- Similar chemical properties
- Gradation in physical properties (such as mp/bp)
What is the general formula of an alkane?
Cn H2n+2
What is the general formula of an alkene?
Cn H2n
What is the general formula of an alcohol?
Cn H2n + 1 OH
What is the general formula of a carboxylic acid?
Cn H2n + 1 COOH
What are saturated compounds?
They contain molecules in which all C-C bonds are single bonds.
What is an unsaturated compound?
Contain one or more C=C bonds.
What is petroleum?
Crude oil - a mixture of hydrocarbons which also contains natural gas.
Where is crude oil found?
Under porous rock (under the ground/in the sea) that is a thick, black and sticky liquid.
What is fractional distillation?
Separating compounds based on their boiling points.
What does each fraction consist of?
Group of hydrocarbons with similar chain lengths. Similiar properties and bp.
What is the process of fractional distillation?
- Crude oil is heated and vapourised
- The vapours of hydrocarbons enter the fractional distillation column with a temperature gradient
- The vapours of hydrocarbons with high bp condense at the bottom of the column
- The vapours of hydrocarbons with lower bp condense and rise to the top
What is viscosity?
Refers to the ease of flow of a liquid.
What is volatility?
Tendency of a substance to vapourise
What is the use of refinery gas?
Heating and cooking. 1-4 carbon atoms. BP: 25>
What is gasoline fuel used for?
Fuel for cars. 4-12 carbon atoms. BP: 40-100
What is naptha used for?
Raw products for producing chemicals. 7-14 carbon atoms. BP: 90-150
What is kerosene used for?
For making jet fuel (parrafin). 12-16 carbon atoms. BP:150-240
What is diesel used for?
Fuel for diesel engines. 14-18 carbon atoms. BP: 220-300
What is fuel oil used for?
Fuel for ships & home heating. 19-25 carbon atoms. BP: 250-320
What is lubricating oil used for?
Used for lubricants, polishes, wax. 20-40 carbon atoms. BP: 300-350
What is bitumen used for?
Surfacing roads. More than 70 carbon atoms. BP: over 350
What does a functional group show?
Group of atoms that determine the chemical properties of a homologous series.
What are 3 fossil fuels?
Coal, natural gas and petroleum.
What is the main constituent of natural gas?
Methane
Properties of alkanes?
Generally unreactive, except for combustion and substitution by chlorine.
What is a substitution reaction?
One atom or group of atoms is replaced by another atom of group of atoms.
What is a substitution reaction of alkanes with chlorine?
A photochemical reaction, with UV light acting as a catalyst - providing activation energy.
Describe manufacture of alkenes and hydrogen:
Cracking larger alkane molecules using a high temperature and a catalyst.
Why do you crack larger alkane molecules?
To make shorter, more useful alkanes, and to form alkenes + hydrogen.
How many products formed in an addition reaction?
One product is formed.
What is the test to distinguish between saturated and unsaturated hydrocarbons?
React with aqueous bromine.
- Saturated: remains orange
- Unsaturated: colourless
What temperature does cracking occur at?
600-700 to vaporise them.
What happens when alkenes react with bromine?
2 bromine atoms add across C=C to form a saturated compound (addition reaction). Bromine water decolorizes.
What happens when alkenes react with hydrogen?
An alkane is formed (through addition reaction). Requires nickel catalyst.
What happens when alkenes react with steam?
An alcohol is formed (addition reaction). Also called a hydration reaction as water is being ADDED. Requires an acid catalyst (phosphoric acid)
How to manufacture ethanol?
- Fermentation of aqueous glucose at 25-35C in the presence of yeast, and in the absence of oxygen.
- Catalytic addition of steam to ethene at 300C and 60 atm in the presence of a phosphoric acid catalyst.
7 methods of fermentation of aqueous glucose:
- Simple equipment needed
- Uses renewable resources
- Batch process (everything mixed in a reaction vessel and left for several days)
- Very slow (several days)
- Produces a dilute solution that requires further processing
6.CO2 produced - greenhouse gas - Low temperatures required
7 methods of hydration of ethene:
- Complex set up required
- Uses non-renewable resources (crude oil)
- Continuous process (reactants constantly passed over catalyst)
- Fast
- Produces pure ethanol
- No greenhouse gases - pollutants formed burning fossil fuels to maintain high temp
- High temp and pressure required - increases energy input and cost
What is the combustion of ethanol?
Ethanol undergoes combustion with oxygen to produce carbon dioxide and water.
What is ethanol used as?
- solvent
- fuel
What does a carboxylic acid reacting with a metal produce?
Salt + hydrogen
What does a carboxylic acid reacting with bases produce?
Salt + water
What does a carboxylic acid reacting with carbonates produce?
Salt + water + carbon dioxide
2 ways ethanoic acid is formed?
- Acidified aqueous potassium manganate (VII): oxidising agent
- Bacterial oxidation during vinegar production
What does a carboxylic acid + alcohol using an acid catalyst form?
Ester
What are polymers?
Large molecules built up from many smaller molecules called monomers.
Describe the formation of poly (ethene)
Addition polymerization using ethene monomers
Can be PET can be converted into monomers and re-polymerised?
Yes.
What are plastics made from?
Polymers.
Are polymers chemically unreactive?
Yes, meaning they are non-biodegradable.
What is bad of incineration of plastic?
Polymers release alot of heat energy when burning and produces CO2 (greenhouse gas). Some polymers release toxic fumes when burning. If incinerated by incomplete combustion, carbon monoxide will be produced which is a toxic gas
What environmental challenges caused by plastics?
- Disposal in landfill sites
- accumulation in oceans
- formation of toxic gases from burning
Describe proteins:
Natural polyamides that are formed from amino acid monomers.
Conditions catalytic cracking
High temperatures and powdered catalyst
alkane general formula
Cn H2n+2
alkene general formula
Cn H2n
alcohol general formula
Cn H2n+1 OH
carboxylic general formula
Cn H2n+1 COOH
what is a functional group
atom/group of atoms that determine the chemical properties of a homologous series
what is structural isomers
compounds with same molecular formula but different structural formulae
what is a protein
natural polyamides that are formed from amino acid monomer
describe formation of poly(ethene)
addition polymerisation using ethene monomers