topic 7 - organic chemistry Flashcards
what is crude oil?
- crude oil is a finite resource found in rocks.
- crude oil is the remains of an ancient biomass consisting mainly of plankton that was buried in mud
what is crude oil a mixture of?
- crude oil is a mixture of a very large number of compounds
- most of the compounds in crude oil are hydrocarbons, which are molecules made up of hydrogen and carbon atoms only
what is the general formula for the homologous series of alkanes?
CnH2n+2
what are the first four members of the alkanes?
- methane
- ethane
- propane
- butane
what is viscosity?
- the thickness of a fluid
- fluids with a high viscosity flow slowly
what occurs as the size of the hydrocarbon molecules increases?
- as the size of the hydrocarbon molecules increases, the molecules get more viscous
what is the flammability of hydrocarbons?
- short-chain hydrocarbons are extremely flammable
- as the size of the hydrocarbon molecules increase, the molecules get less flammable
- so long-chain hydrocarbons are very difficult to burn
what is the boiling point?
- the temperature at which a liquid turns to a gas
what are the boiling points of hydrocarbons?
- short-chain hydrocarbons have low boiling points
- as the size of the hydrocarbon molecules increases, the boiling points also increases
- very long chain hydrocarbons have very high boiling points
what is the state of hydrocarbons at room temperature?
- gases
- their boiling points are lower than room temperature
what do hydrocarbon fuels release when combusted?
- energy
what occurs during the combustion of hydrocarbon fuels?
- during combustion, the carbon and hydrogen atoms in the fuel react with oxygen
- the carbon and hydrogen are oxidised
- if the oxygen is unlimited, this reaction produces carbon dioxide and water
what is the word equation for the complete combustion of methane?
methane + oxygen -> carbon dioxide + water
how does fractional distillation of crude oil take place?
- crude oil is heated and vaporised
- vapor rises up to the fractionating column
- the column is hotter at the bottom and cooler at the top
- hydrocarbons cool as they go up the column and cooler at the top
- hydrocarbons cool as they go up the column and condense at different heights as they have different boiling points
- large molecules, high boiling points - collected at the bottom
- small molecules, low boiling points - collected at the top
- this gives fractions which can be used in various ways
what are examples of fractions used as fuels?
- petrol and diesel
- kerosene
- heavy fuel oil
- liquified petroleum gas
what is feedstock?
- a feedstock is a chemical that is used to make other chemicals
what are examples of feedstock?
- solvents
- lubricants
- detergents
- polymers
what is cracking?
hydrocarbons being broken down to produce smaller, more useful molecules
what type of reaction is cracking?
- thermal decomposition
what is catalytic cracking?
- in catalytic cracking, we use high temperatures and a catalyst
what is steam cracking?
- in steam cracking we use high temperature and steam
what are alkenes used to make?
- polymers
which is more reactive: alkanes or alkenes?
alkenes
how do you test for alkenes?
- we test for alkenes using bromine water, which is orange
- if shaken with alkene, then the bromine water becomes colourless
what is the general formula for alkenes?
CnH2n
why are alkenes unsaturated?
- they contain 2 fewer hydrogen atoms than the alkane with the same number of carbon atoms
what are the names and formulae of the first 4 members of the homologous series of alkenes?
- ethene (C2H4)
- propene (C3H6)
- butene (C4H8)
- pentene (C5H10)
what is the functional group for alkenes?
C = C
how does the combustion of alkenes differ from the combustion of alkanes?
alkenes tend to undergo incomplete combustion so burn with a smoky flame
what is the catalyst needed for the reaction of hydrogen with an alkene?
nickel catalyst
what is the reaction between ethene and hydrogen?
ethene + hydrogen -> ethane
what is the formula for the reaction between a halogen?
ethene + chlorine -> dichloroethane
what catalyst is used for the reaction between an alkene and steam?
acid
what is the formula for the reaction between ethene and water?
ethene + water -> ethanol
- 300°
- phosphoric acid
what is the functional group for alcohol?
- OH
what are the names and chemical formulae of the first 4 members of the homologous series of alcohols?
- methanol (CH3OH)
- ethanol (C2H5OH)
- propanol (C3H7OH)
- butanol (C4H9OH)
what is the structural formula for the first 4 members of the homologous series of alcohols?
- methanol (CH3OH)
- ethanol (C2H5OH)
- propanol (CH3CH2CH2OH)
- butanol (CH3CH2CH2CH2OH)
how is ethanol made from glucose?
ferment sugar solutions (glucose) using yeast
what is the balanced equation for the complete combustion of ethanol?
C2H5OH + 3O2 -> 2CO2 + 3H2O
what is observed when alcohols react with sodium metal?
the sodium effervesces
what is the word equation for the reaction of sodium with ethanol?
sodium + ethanol -> sodium ethoxide + hydrogen
what happens when alcohol is added to water?
they mix and a neutral solution is produced
what happens when an alcohol reacts with an oxidising reagent?
a carboxylic acid is produced
what are 3 uses of alcohols?
- solvents
- alcoholic drinks
- fuels
what is the functional group for carboxylic acids?
- COOH
what are the names and chemical formulae of the first 4 members of the homologous series of carboxylic acids?
- methanoic acid (HCOOH)
- ethanoic acid (CH3COOH)
- propanoic acid (C2H5COOH)
- butanoic acid (C3H7COOH)
what happens when carboxylic acids dissolve in water?
an acidic solution forms
what is formed when carboxylic acids dissolve in water?
an acidic solution forms
what is formed when a carboxylic acid reacts with a metal carbonate?
a salt, carbon dioxide and water
what is the word equation for the reaction between ethanoic acid and sodium carbonate?
- ethanoic acid + sodium carbonate -> sodium ethanoate + carbon dioxide
why are carboxylic acids considered weak acids?
carboxylic acids only partially ionise in water
what is formed when a carboxylic acid reacts with alcohol?
an ester and water
what catalysts are needed for this reaction to take place?
sulphuric acid
what is the word equation for the reaction of ethanoic acid with ethanol in the presence of sulphuric acid catalyst
ethanoic acid + ethanol ⇌ ethyl ethanoate + water
what are the 2 properties of esters?
- pleasant smell
- volatile
what are 2 uses of esters?
- perfumes
- food flavourings
what is a polymer?
- a long molecule made up of lots small units (monomers) joined together
what are 2 types of polymers?
- addition polymers
- condensation polymers
what is formed if an ethene monomer undergoes addition polymerisation?
poly(ethene)
what is the structure in brackets known as?
repeating units
what are the reaction conditions for addition polymerisation?
- high temperature
- high pressure
- titanium catalyst
what is the difference between addition and condensation polymerisation?
- in addition polymerisation, only one product is formed whereas in condensation polymerisation two different products are formed
- condensation polymerisation involved monomers with 2 different functional groups whereas addition polymerization involves just 1 functional group
how many different functional groups does an amino acid molecule have?
2
what are the two different functional groups in a molecule of an amino acid?
- COOH
- NH2
what type of reaction occurs for amino acids to produce a polypeptide?
condensation polymerisation reaction
what are two uses of proteins?
- hormones
- enzymes
what monomers is DNA made from?
- nucleotide
how many different nucleotides ar there?
4
describe the structure of DNA
2 polymer strands in the form of a double helix made up of 4 different nucleotides
what does a nucleotide monomer consist of?
- a phosphate group attached to a sugar molecule attached to one of four bases
what are the four bases?
A, T, C, G
what polymer is formed when a glucose monomer?
- starch or cellulose
