Organic chemistry

  • Created by: leo1223
  • Created on: 30-05-18 12:50
What is crude oil?
Crude oil is a finite resource that is used to produce fuels, it has formed over millions of years from fossilised remains, it consists of large hydrocarbon chains
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What affect the properties of hydrocarbons?
The size of hydrocarbon molecules affects their properties
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What properties are affected by the size of the hydrocarbon moleclue?
The viscosity (larger hydrocarbon = more viscous), boiling point (larger hydrocarbon = higher boiling point), volatility (larger hydrocarbon = less volatile), flammability (larger hydrocarbon = less flammable)
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How can crude oil be separated into different fractions/hydrocarbons?
Fractional distillation
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Describe the process of fractional distillation?
First crude oil is heated until it evaporates, the vapour moves up the fractionating column, the top of the column is colder than the bottom, shorter hydrocarbons can reach the top before they condense where as longer hydrocarbons condense at bottom
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Describe the properties of alkanes?
Alkanes only contain single bonds and are know as saturated hydrocarbons, alkanes are fairly unreactive but burn well, all carbon atoms are linked to another four atoms
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How does the length of the alkane chain affect their energy output?
The shorter-chain alkanes release energy more quickly by burning, so there is a greater demand for them as fuels
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What is the general formula for alkanes?
C*nH*2n+2
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Describe the process of combustion when hydrocarbons are involved?
During the combustion of hydrocarbon fuels, both carbon and hydrogen are oxidised, energy is released, waste products are produced, which are released into the atmosphere
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What is produced if combustion of hydrocarbon fuels is incomplete?
If combustion is not complete, then carbon monoxide, unburnt fuels and solid particles containing soot may be released
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What do solid particles (soot) cause when released in the atmosphere?
If solid particles or particulates are released into the air, it can cause global dimming by reducing the amount of sunlight reaching the earth's surface and can cause damage to people's lungs
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What are the effects of the high temperatures reached from the combustion of fuels?
The high temperatures reached when fuels are burned can cause nitrogen in the air to react with oxygen to form nitrogen oxides. Which can cause respiratory problems and react with rain water to form acid rain, which can damage buildings and plants
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What are the effects of carbon monoxide being released from the combustion of fuels?
Carbon monoxide is a colourless, odourless and toxic gas which can harm humans
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What is cracking?
Cracking is a process whereby longer-chain hydrocarbons can be broken down into shorter, more useful hydrocarbons
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Explain the process of cracking?
During cracking: the hydrocarbons are heated until they vaporise, the vapour is passed over a hot catalyst, a thermal decomposition reaction then takes place, the products formed include both alkanes and alkenes
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Why is there a high demand for short-chain hydrocarbons?
Short-chain hydrocarbons are in high demand as they are easier to ignite than longer chains and have low boiling points
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Describe the properties of alkenes?
Alkenes contain at least one double bond between two carbon atoms, not all carbon atoms are linked to four other atoms, alkenes are know as unsaturated hydrocarbons as they have at least one double bond
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What is the general formula for alkenes?
C*nH*2n
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Why are alkenes more reactive than alkanes?
Alkenes are more reactive than alkanes due to the double bond
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How can alkenes produce alkanes?
If hydrogen is added to alkenes it will produce alkanes, in this reaction a nickel catalyst is used, this is know as an addition reaction
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How can ethanol be produced (hydration)?
If ethene reacts with steam in the presence of a catalyst (phosphoric acid) ethanol will be formed, this is know as an addition reaction, this is know as hydration
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What happens when an alkene is added to bromine water and shaken?
When an alkene is added to bromine water and shaken , it turns the orange solution into colourless, this reaction shows that an alkene is present, this is an addition reaction
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What happens when an alkane is added to bromine water and shaken?
When an alkane is added to bromine water and shaken, there is no colour change therefore no reaction takes place, this reaction shows that an alkane is present
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What can the reaction between an alkane/alkene and bromine water be used to find out?
Whether a substance is either a alkane or alkene, if the colour changes, an alkene is present, if there is no distinct colour change, an alkane is present
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How can ethanol be produced (fermentation)?
Aqueous solutions of ethanol can be produced by the fermentation of sugar, the sugar produces ethanol and carbon dioxide. Temperatures of 25 to 50 work best, too low-rate of reaction slows as yeast becomes inactive, too high- yeast is denatured
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What are alcohols?
Alcohols are carbon-based molecules that contain the functional group hydroxyl, -OH
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What are methanol, ethanol, propanol and butanol part of?
Methanol, ethanol, propanol and butanol are the first four members of the homologous series of alcohols, meaning they are all react in similar ways
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Describe the properties of alcohols?
Alcohols dissolve in water to form neutral solutions, alcohols react with sodium to form hydrogen, when burnt in the air they produce carbon dioxide and water, they can be used as fuels and solvents, react with carboxylic acids to form esters
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How can ethanoic acid be produced from ethanol?
Ethanol can be oxidised to ethanoic acid by chemical oxidising agents or by the action of bacteria from the air
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What are carboxylic acids?
Carboxylic acids are organic compounds that contain the functional group carboxyl, -COOH
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Describe the properties of carboxylic acids?
Carboxylic acids dissolve in water to form acidic solutions, they react with carbonates to produce carbon dioxide, they react with alcohols (in presence of an acid catalyst) to form esters, they do not ionise fully in water, so they are weak acids
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What are esters?
Esters contain the functional group -COO
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Describe the properties of esters?
Esters are volatile compounds i.e. they have low boiling points, they have distinctive smells and are used in perfumes and as flavourings in foods
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What is produced when ethanol and ethanoic acid react together?
When ethanol and ethanoic acid react together, the ester formed is ethyl ethanoate
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What two functional groups do amino acids contain?
Amino acids contain two different functional groups, the amine group, -NH*2 and the carboxyl group, -COOH
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Name one amino acid
Glycine, NH*2CH*2COOH
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What is formed when multiple different amino acids join together?
Multiple different amino acids join together to form polymers called proteins
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Describe the properties of Deoxyribonucleic acid (DNA)?
DNA is a very large molecule, it is essential for life as it transmits instructions for the development of living organisms and some viruses, DNA has a double helix shape
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What is DNA made from?
DNA is made from two polymer chains constructed from four different nucleotides: cytosine, guanine, adenine and thymine, the two polymer chains form a double helix
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What are starch and cellulose?
Both starch and cellulose are polymers of sugars, that are made by plants and are important for life, sugar, starch and cellulose are all carbohydrates
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What is a functional group?
A functional group is the part of a molecule that gives it its characteristic properties
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Why are alkenes useful for making polymers?
Alkenes are useful as they are unsaturated which makes them useful at making long chain molecules know as polymers
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What is a monomer?
Monomers are small molecules with double bonds
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What is a polymer?
Polymers are long-chain molecules, formed by many monomers which have joined together
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What is the process whereby monomers join together to form polymers?
Addition polymerisation
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What type of polymer is plastic?
Plastics are synthetic polymers made by addition polymerisation
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Describe reoccurring features of addition polymerisation reactions?
In addition polymerisation reactions, the repeating unit and the monomer units contain the same atoms, the percentage atoms economy is 100%
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What two factors determine the properties of a polymer?
The properties of a polymer depend on: what it is made from, i.e. what monomer is used, the conditions (e.g. temperature and catalyst) under which it was made
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Why does poly(ethene) form the same polymer with different properties?
Low and high density poly(ethene) are both made from the same monomer however the polymers have different properties because different catalysts and reaction conditions are used to make them
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Name 1 use of low density poly(ethene) and 1 use of high density (poly)ethene
Low density poly(ethene) - carrier bags, High density poly(ethene) - plastic bottles
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Describe the properties of thermosoftening polymers?
Thermosoftening polymers such as poly(ethene) consist of individual polymer chains that are tangled together, they have weak intermolecular forces between all of the polymer chains and soften on heating
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Describe the properties of thermosetting polymers?
Thermosetting polymers such as melamine consist of polymer chains that are joined together by cross-links, they do not melt when they are heated
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Explain what happens in condensation polymerisation reactions?
In condensation polymerisation reactions, monomer molecules join together to form large polymer molecules and lose small molecules such as water, as by-products
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What are diols?
Diols are molecules with two hydroxyl groups, -OH
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How are the simplest polymers formed?
The simplest polymers are formed when diols join together with dicarboxylic acids
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What are dicarboxylic acids?
Dicarboxylic acids are molecules with two carboxyl groups, -COOH
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What do amino acids join together by? What do amino acids join together to form?
Amino acids join together by condensation polymerisation to form polypeptides and water
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Describe the formation of molecules in polypeptides?
Polypeptides contain lots of peptide links, a peptide link is the bond formed between carboxyl gores and the amino groups when amino acids join together
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Card 2

Front

What affect the properties of hydrocarbons?

Back

The size of hydrocarbon molecules affects their properties

Card 3

Front

What properties are affected by the size of the hydrocarbon moleclue?

Back

Preview of the front of card 3

Card 4

Front

How can crude oil be separated into different fractions/hydrocarbons?

Back

Preview of the front of card 4

Card 5

Front

Describe the process of fractional distillation?

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