C7 Flashcards
What is a hydrocarbon?
A hydrocarbon is any compound that is formed from hydrogen and carbon atoms only
What are alkanes?
Alkanes are a group of organic compounds that react in a similar way (homologous series) and are saturated compounds (only have single carbon bonds)
What the general formula for alkanes?
Cn H2n+2
What are the first 4 alkanes and their formulas
Methane-CH4
Ethane-C2H6
Propane-C3H8
Butane-C4H10
Why do hydrocarbon properties change?
1) The shorter the hydrocarbon the less viscous (more runny) it is
2) Hydrocarbons with shorter chains are more volatile and flammable
What do the properties of Hydrocarbons affect how they’re used for?
The properties of hydrocarbons affect how they’re used for fuels
What’s the word equation for complete combustion of oxygen?
Hydrocarbon +oxygen —> carbon dioxide + water (+energy)
What does the complete combustion of any hydrocarbon in oxygen release?
lots of energy
During combustion what happens to the carbon and hydrogen?
The carbon and hydrogen are oxidised
What is crude oil?
Crude oil is a finite resource found in rocks and is the remains of an ancient biomass consisting mainly of plankton that was buried in mud.
How do remains turn into crude oil
Over millions of years with high temperature and pressure the remains turn into crude oil
What is crude oil a mixture of?
Crude oil is a mixture of different hydrocarbons (mostly alkanes)
What are the steps to the different compounds in crude oil being separated by fractional distillation
1) The oil is heated until most of it turns into gas. The gases enter a fractionating column.
2) In the column there’s a temperature gradient (hot at the bottom and gets cooler as you go up)
3) The longer hydrocarbons have high boiling points. They condense back into liquids and drain out of the column early on, near the bottom
Shorter hydrocarbons have lower boiling points, they condense and drain out near the top of the column later on (cooler).
Results of fractional distillation?
End up with crude oil mixture separated out into different columns. Each fraction has a mixture of hydrocarbons that all contain a similar number of carbon atoms, so have similar boiling points
What can the fractions be processed to produce and what does this produce?
The fractions can be processed to produce fuels and feedstock for the petrochemical industry to produce polymers, solvents, lubricants and detergents.
What does crude oil provide?
Oil provides the fuels for transport (petrol, diesel, kerosene, heavy fuel oil and LPG)
Why is there such a large variety of products of crude oil?
Crude oil products are organic compounds with carbon atoms and the carbon atoms can bond together to form families of similar compounds, therefore large variety of products
What is cracking?
Cracking is the breaking down of long chain hydrocarbons into shorter more useful molecules
What are products of cracking useful for?
Short chain hydrocarbons are flammable so make good fuels and are in high demand
What type of reaction is cracking?
Cracking is a thermal decomposition reaction- breaking molecules down by heating them.
What are the two types of cracking?
- Catalytic cracking
-Steam cracking
What are the steps of catalytic cracking?
1) Heat long chain hydrocarbons to vaporise them ( turn into a gas)
2)The vapour is passed over a hot powdered aluminium catalyst
3) The long-chain molecules split apart on the surface of the catalyst
What are the steps of steam cracking?
1) Vaporise long chain hydrocarbons
2) Mix them with steam
3) Heat them to a very high temperature
What are alkenes?
Alkenes are hydrocarbons with a double carbon bond
Why are alkenes unsaturated?
Alkenes are unsaturated because they have 2 fewer hydrogens than alkanes with the same number of carbons
What is the general formula for alkenes?
CnH2n
What are the first 4 alkenes and there formulas?
Ethene- C2H4
Propene-C3H6
Butene-C4H8
Pentene-C5H10
What are alkenes used to produce?
Alkenes are used to produce polymers and as starting materials for the productions of many other chemicals.
Why are alkenes reaction (far more than alkanes)?
The C=C bond can open up to make a single bond allowing the two carbon atoms to bond with other atoms.
What happens when you burn alkenes and what is produced?
They undergo incomplete combustion- carbon and carbon monoxide (poisonous gas) are produced as well as carbon dioxide and water.
What does incomplete combustion of alkenes result in?
A smoky yellow flame and less energy being released compared to complete combustion.
What is a functional group?
A functional group is a group of atoms that determines how the molecules typically reacts.
What is an alkenes functional group?
All alkenes functional group is C=C so they all react in similar ways.
How do alkenes react via addition reactions?
The carbon-carbon double bond will open up to leave a single bond and a new atom is added to each carbon.
Explain hydrogenation (addition of hydrogen to an alkene)
Hydrogen reacts with the double-bonded carbons to open up the double bond and form the equivalent, saturated alkanes- done with a catalyst.
How do alkenes form alcohols?
When alkenes react with steam, water is added across the double bond and an alcohol is formed.
Passing over Catalyst (ethanol)
What happens in addition reactions of halogens (bromine ,chlorine ,iodine) to alkenes?
The molecules formed are saturated with the C=C carbons each becoming bonded to a halogen atom.
E.g. bromine +ethene–> dibromoethane
How can the addition of bromine to a double bond be used to test for alkenes?
When orange bromine water is added to a saturated compound (like an alkane), no reaction will happen and it’ll stay bright orange.
If its added to an alkene the bromine will add across the double bond, making a colourless dibromo-compound- so the bromine water is decolourised.
What are polymers?
Polymers are long molecules formed when lots of small molecules called monomers join together.
What is the reaction of forming polymers called and what conditions are needed for it?
Polymerisation- needs high pressure and a catalyst.
What are plastics made up from?
Plastics are made up of polymers which are usually carbon based and their monomers are often alkenes.
What do the monomers that make up the addition polymers have
A double covalent bond
What is addition polymerisation?
Addition polymerisation is when lots of unsaturated monomer molecules (alkenes) can open up their double bonds and join together to form polymer chains.
Why do in polymers the repeating units have the same atoms as the monomer?
Because no other molecules is formed in the reaction.
What is the functional group of alcohols?
-OH
What is the general formula for Alcohols?
Cn H2n+1 OH
What are the first four alcohols
Methanol- CH3OH
Ethanol-C2H5OH
Propanol-C3H7OH
Butanol-C4H9OH
Why do alcohols undergo complete combustion in air and what do they produce?
Alcohols are flammable. They produce carbon dioxide and water when undergoing complete combustion.
What happens when alcohols are added in water?
They’re soluble in water because their solutions have a neutral pH
What happens when alcohols react with sodium (one of the products)?
Hydrogen
What happens when alcohols are oxidised?
They produce a carboxylic acid
What do different alcohols form?
Different carboxylic acids
What are some uses of alcohols?
Solvents and fuels
Why are alcohols used as solvents
They are used as solvents because they can dissolve most things water can dissolve and also cant (hydrocarbons, oils and fats)
What is ethanol made using?
Fermentation
What is fermentation?
Fermentation uses an enzyme in yeast to convert sugars into solutions of ethanol and carbon dioxide is also produced.
What are the conditions needed for fermentation?
-37 degrees (temp)
-slightly acidic condition
-anaerobic conditions (no oxygen)
Why are these the conditions needed for fermentation?
The enzyme in yeast works best at these conditions to convert the sugar to alcohol. If it weren’t at these conditions the enzyme could be denatured or work at a slower rate.
What’s the functional group for carboxylic acids and what are they?
-COOH
Carboxylic acids are a homologous series of compounds
What are the 4 carboxylic acids?
Methanoic acid- HCOOH
Ethanoic acid- CH3COOH
Propanoic-C2H5COOH
Butanoic acid- C3H7COOH
What do carboxylic acids produce when reacted with carbonates?
They produce a salt, water and carbon dioxide ( like any other acid)
What do salts formed in carboxylic acid reactions end in?
‘anoate’ eg methanoic acid =methanoate ethanoic acid=ethanoate
1)What happens when carboxylic acids dissolve in water?
2)Why are carboxylic acids weak acids?
1)When carboxylic acids dissolve in water they ionise and release H+ ions resulting in an acidic solution.
2)But because they don’t ionise completely ( not all the acid molecules release their H+ ions) they form weak acid solutions.
What does it mean if carboxylic acids are weak acids?
It means they have a higher pH ( are less acidic) than aqueous solutions of strong acids with the same concentration.
How are esters formed and what is their functional group?
Esters are formed from an alcohol and a carboxylic acid. -COO
How is ethyl ethanoate (ester) made?
Ethanoic acid+ ethanol —> ethyl ethanoate + water
What is condensation polymerisation and what does it make?
Condensation polymerisation involves monomers with two functional groups which react together and bonds form between them, making polymer chains.
Why is condensation polymerisation a condensation reaction?
For each new bond formed a small molecule (eg water) is lost therefore condensation reaction
How are the simplest types of condensation polymers produced?
The simplest polymers are produced from two different monomers with two of the same functional groups on each monomer.
What is the differences between the number of types of monomers in addition and condensation polymerisation?
In addition there are only 1 monomer type containing a C=C bond.
In condensation there are two monomer types each containing two of the same functional groups.
What is the difference between the number of products in addition and condensation polymerisation?
In addition there is only one product formed.
In condensation there is two types of product- the polymer and a small molecule ( e.g. water)
What is the difference between the functional groups involved in addition and condensation polymerisation?
In addition there is a carbon-carbon double bond in monomer.
In condensation there are two reactive groups on each monomer.
What two functional groups do amino acids have?
A basic amino group (NH2) and an acidic carboxyl group (COOH)
What do amino acids react by to form polypeptides?
Amino acids react by condensation polymerisation to produce polypeptides.
Why is a molecule of water lost when forming a polymer chain?
The amino group of an amino acid can react with the acid group of another to form a polymer chain. For every new bond formed a molecule of water is lost.
How are proteins made?
Different amino acids can be combined in the same chain to produce proteins.
What is the smallest amino acid possible and what does it polymerise to produce?
Glycine-polymerises to produce the polypeptide.
What is DNA?
DNA (deoxyribonucleic acid) is a large molecule essential for life.
What does DNA do?
DNA encodes genetic instructions for the development and functioning of living organisms and viruses.
What is DNA made of?
DNA is made up of two polymer chains, made from 4 different monomers called nucleotides (bases - ATGC), in the form of a double helix.
How do sugars (monomers) react together to form larger carbohydrate polymers?
Sugars can react together through polymerisation reactions to form larger carbohydrate polymers.
What are some of the polymers sugar (monomer) can make?
- Starch- livings things use to store energy
-Cellulose-found in plant cell walls
