YEAR 11
Separate Chemistry – Booklet 2a
Lesson Recall Knowledge Check
1. Hydrocarbons and Fractional Distillation /8 /82. Products and Trends of Fractional Distillation /8 /83. Cracking and Testing Alkanes and Alkenes /8 /84. Alkenes and Reactions /8 /85. Alcohols and Carboxylic Acids /8 /86. Polymerisation and Polymers /8 /8
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Name: ____________________________________________
Teacher: __________________________________________
Class: _____________________________________________
Chemistry Knowledge Web
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Overview of the topics and skills taught over Year 11
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Knowledge
Biology
Inheritance, Variation and Evolution
Ecology
Chemistry
The Rate and Extent of Chemical Change
Organic Chemistry
Chemical Analysis
Physics
Waves
Magnetism and Electromagnetism
Space (Separate Science Only)
Key Skills
Using laboratory equipment safely
Practical skills using scientific equipment
Making and recording observations
Using models to understand concepts
Using key vocabulary
Topic Big Statement
The aim of the topics taught in this booklet is to explain how useful products can be obtained from crude oil and to understand how different techniques can be used to separate mixtures and identify the chemicals that they are made of.
Where the Unit Fits in the Sequence
These are the final topics you will learn in chemistry, as they build on all of the ideas you have learned so far and require you to use the skills that you have acquired.
The target 9 activities in this booklet will extend your knowledge.
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Threshold Concepts
By the end of the unit you should be able to: R A G
State the general formula of alkanes.
Describe the process of fractional distillation.
Identify alkanes and alkenes using bromine water.
Describe the reactions of alkenes, alcohols and carboxylic acids.
Describe the process of polymerisation.
Explain how mixtures are separated by chromatography.
Calculate Rf values.
Use simple tests to identify common gases.
Describe the tests to identify different ions.
Relevant core questions, linked to this unit: 5
Core Question: Answer:Define the term hydrocarbon.
Hydrocarbons are compounds that contain hydrogen and carbon only.
Name the process used to separate crude oil.
Fractional distillation.
Describe how the flammability of hydrocarbons changes as the length of hydrocarbon increases.
As hydrocarbons get longer, their flammability decreases.
Describe the products of cracking.
During cracking, long alkanes are split into a shorter alkane and alkene.
Explain why pencil is used to draw the start line on a chromatogram.
Pencil does not dissolve in the solvent and therefore it will not affect the results.
Describe the test for hydrogen gas.
There is a squeaky pop sound when you insert a burning splint into a tube of the gas.
Describe the test for carbon dioxide
When carbon dioxide is bubbled through limewater, the limewater changes from clear and colourless to cloudy and milky.
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Knowledge OrganiserThe keywords for this topic will appear in this order:
Word Meaning
crude oil A fossil fuel, in the liquid state, formed from the remains of microscopic dead plants and animals that lived in the sea.
fractional distillation
A method of separating a mixture of liquids with different boiling points into individual components (fractions).
viscosity How thick or runny a liquid is. Low viscosity is very runny, high viscosity is thick.
alkane A hydrocarbon in which all the bonds between the carbon atoms are single bonds.
general formula A type of formula that represents the composition of any member of an homologous series.
alkene A hydrocarbon in which there are one or more double bonds between carbon atoms.
cracking A chemical reaction in which large alkane molecules are split into two or more smaller alkanes and alkenes.
alcohols An homologous series of compounds that contain the –OH functional group.
carboxylic acids An homologous series of compounds that contain the –COOH functional group.
polymerisation A reaction in which a large number of small molecules (monomers) join together to form a long chain molecule (polymer).
chromatography A technique for separating the components of a mixture – for example different food colouring agents.
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Tier 3 Vocabulary
Word Meaning In a sentence
crude oil A fossil fuel, in the liquid state, formed from the remains of microscopic dead plants and animals that lived in the sea.
Crude oil is a mixture of hydrocarbons.
hydrocarbon A compound containing hydrogen and carbon only.
Hydrocarbons are found in crude oil.
fraction A component of a mixture that has been separated by fractional distillation.
The different hydrocarbons in crude oil are called fractions.
fractional distillation
A method of separating a mixture of liquids with different boiling points into individual components (fractions).
Fractional distillation is used to separate the different fractions in crude oil.
viscosity How thick or runny a liquid is. Low viscosity is very runny, high viscosity is thick.
Higher viscosity hydrocarbon have higher boiling points.
alkane A hydrocarbon in which all the bonds between the carbon atoms are single bonds.
Alkanes are saturated hydrocarbons.
general formula A type of formula that represents the composition of any member of an homologous series.
The general formula for an alkane is CnH2n+2.
alkene A hydrocarbon in which there are one or more double bonds between carbon atoms.
Alkenes are unsaturated hydrocarbons.
cracking A chemical reaction in which large alkane molecules are split into two or more smaller alkanes and alkenes.
Cracking turns large alkanes into shorter, more useful alkanes and alkenes.
saturated A molecule that contains only single bonds between the carbon atoms in a chain.
Saturated hydrocarbons only contain single bonds.
unsaturated A molecule that contains one or more double bonds between carbon atoms in a chain.
Unsaturated hydrocarbons contain one or more double bonds.
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Word Meaning In a sentence
homologous series
A family of compounds that have the same general formula and similar properties, but have different numbers of carbon atoms.
Compounds in a homologous series have the same general formula.
alcohols An homologous series of compounds that contain the –OH functional group.
Alcohols burn well in oxygen.
carboxylic acids An homologous series of compounds that contain the –COOH functional group.
Carboxylic acids are weak acids.
monomer A small molecule used to make a polymer.
Monomers are joined together to make polymers.
polymer A long-chain molecule made by joining many smaller molecules (monomers) together.
Polymers are made over several hundred or thousand monomers.
Baseline Assessment
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1 What happens in all chemical changes?
a A gas is produced.
b Heat energy is given out.
c Elements change into a compound.
d One or more new substances are formed.
2 A compound contains:
a only one type of atom.
b only one element.
c only two elements joined together.
d at least two elements joined together.
3 Which of the following always happens during a chemical reaction?a Compounds react and split up into free
atoms.b Elements join together to make new
elements.c Atoms are broken down into smaller
particles.d The atoms in the reactants are rearranged
to make the products.
4 This chromatogram was made using black ink. How many different coloured inks were in the mixture?
a 4 b 6
c 5 d 7
5 What is chromatography used for?
a to separate a solid from a liquid
b to separate out dissolved solids
c to separate a liquid from a solution
d to separate a mixture of liquids
6 Why do the substances separate in a chromatogram?
a The solvent dissolves the substances and carries them up the paper.
b Some of the substances evaporate before the others.
c The solvent carries the substances at different speeds.
d The solvent evaporates at different points up the chromatogram.
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7 In this chromatography experiment, why are the sample points placed above the water line?
a so that the samples don’t dissolve in the water at the bottom
b so that the pencil line dissolves as the water moves up the paper
c so that the samples evaporate
d so that the samples mix together
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Lesson 1 – Hydrocarbons and Fractional DistillationRecall
1. Name three non-metal elements.
2. Describe what is meant by a mixture.
3. Define the term ‘boiling point’.
4. Explain why the hydrocarbons in crude oil have different boiling points
5. Describe what distillation is used for.
6. Define the term fuel.
7. Describe what happens to electrons during the formation of a covalent bond.8. Name the elements found in methane (CH4).
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. Crude oil is a mixture of a very large number of compounds.
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https://www.youtube.com/watch?v=8YHsxXEVB1M
Task - during the video either make notes or jot down some key / tier 3 vocabulary that you hear.
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Task – now use your notes to answer the following questions. Your aim is to complete ALL levels and pick up as many points as you can.
My answers-
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Hydrocarbons
Most of the compounds in crude oil are hydrocarbons, which are molecules made up of hydrogen and carbon atoms only. Here are a selection of hydrocarbon structure diagrams:
Most of the hydrocarbons in crude oil are called alkanes.
An alkane is a type of hydrocarbon where the carbon and hydrogen are all joined by SINGLE covalent bonds. This is indicated in structure diagrams by a single straight line, see below:
The general formula for the homologous series of alkanes is CnH2n+2.
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A single covalent bond – this means there is one shared pair of electrons between the atoms on either end of the line
Tier 3 language - homologous series
This simply refers to a chemical family, or a group of compounds that share a common structure and therefore certain properties.
The general formula means that for every one carbon atom to work out the number of hydrogen atoms in that formula you simply multiply that number by 2 and then add 2.
Task - Look at this worked example and then fill in the missing formulae
Name of alkane and number of carbon atoms
Working out Formula
Methane (1) Carbon = 1Hydrogen = 1 x 2 = 22+2 = 4
CH4
Ethane (2)
Propane (3)
Butane (4)
The first four members of the alkanes are methane, ethane, propane and butane.
When naming alkanes be aware that the prefix links to the number of carbons in the hydrocarbon - meth=1, eth=2, prop=3 and but =4. The suffix indicates what kind of hydrocarbon it is, ane = alkane and ene=alkene (more about these in another lesson).
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Fractional distillation
As we have mentioned, crude oil is a mixture of a very large number of compounds. In order to get the most out of each part of the mixture, the substances must be separated and purified. The process used to separate the different compounds in crude oil is called fractional distillation. Each of the fractions share a similar number of carbons and boiling point.
Look at this image of the process of fractional distillation:
A tall fractionating column is fitted above the mixture, with several condensers coming off at different heights. The column is hot at the bottom and cool at the top. Substances with high boiling points condense at the bottom and substances with lower boiling points condense on the way to the top.
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Knowledge Check
1. Define the term ‘finite resource’.
2. Name the substances found in crude oil.
3. Define the term ‘hydrocarbon’.
4. State what is represented by each line on this diagram.
5. Explain why a general formula is useful.
6. State the purpose of fractional distillation.7. Explain what chemicals have in common at each level in the fractioning column. 8. Describe a property of molecules found at the top of the fractionating column.
Target 9 extension task: [check answers in appendix]
(a) Methane is burned in a plentiful supply of oxygen.
Which is the correct balanced chemical equation?
Tick one box.
CH4 + O2 → CO2 + H2O
CH4 + 2O2 → CO2 + H2O
CH4 + 2O2 → CO2 + 2H2O
CH4 + 3O2 → 2CO2 + 2H2O
(1)
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(b) Burning fuels causes atmospheric pollution.
Write one effect for each pollutant in Table 1.
Table 1
Pollutant Effect
Carbon monoxide
Sulfur dioxide
Particulates
(3)
(c) Methane, petrol and coal are fuels.
Table 2 shows information about these fuels.
Table 2
Fuel State Energy content in kJ per g
Mass in mg of CO2
produced for one kJ of energy released
Methane Gas 52 53
Petrol Liquid 43 71
Coal Solid 24 93
Evaluate the use of the fuels.
Use in the information in Table 2 and your knowledge.
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Lesson 2 – Products of Fractional DistillationRecall
1. Describe how crude oil is formed.
2. Name the process that separates the substances in crude oil.
3-5. Draw a diagram of a solid, liquid and gas.
6. Describe some differences between liquids and gases.
7. Describe what happens during a displacement reaction.
8. Describe how ions are formed.
In our last lesson we considered the important natural material called crude oil. We learnt that it is a complex mixture of hydrocarbons. We now know that a process called fractional distillation can be used to separate the different compounds found in this mixture. This process uses the different boiling points of the fractions to separate them through heating, evaporation and condensing of the chemicals.
The reason scientists go to the trouble of separating the mixture is because the products are so useful. The fractions can be processed to produce fuels and feedstock for the petrochemical industry. Many of the fuels on which we depend for our modern lifestyle, such as petrol, diesel oil, kerosene, heavy fuel oil and liquefied petroleum gases, are produced from crude oil. Many useful materials on which modern life depends are produced by the petrochemical industry, such as solvents, lubricants, polymers, detergents.
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Sequencing Task
Put the steps of fractional distillation in the correct order.
The vaporised crude oil enters the fractionating column, which is hottest at the bottom.The vapours condense when they become cool enough.
The shortest hydrocarbons leave the fractionating column at the top.
Vapours from the oil rise through the column.
The different fractions (in liquid form) are led out of the column at different heights.Crude oil is heated until it evaporates.
Watch the attached video with your teacher and make any notes you think would be useful to revise from: https://www.youtube.com/watch?v=PYMWUz7TC3A
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Extended writing challenge: Hydrocarbons
Describe and explain how the different hydrocarbons are separated from the mixture in crude oil.
Use the diagram to help you with your answer.
Properties of the fractions:
You have been previously told that different chemicals have different properties and that these properties fall into two main categories. Those categories where chemical and physical properties. Chemical properties cover the way the chemical reacts with others and the reasons for this relating to electron configuration. The physical properties were all the other traits that chemical has such as colour, boiling point, and viscosity.
Here we will consider how the structure of the chemical from the fractioning column links the properties it has. We need to recall that the smallest carbon chain hydrocarbons are found to condense and collect at the top of the column and the largest at the bottom.
As we can see from the image here, the size of the carbon chain impacts the chemical’s following physical properties: boiling point, viscosity and flammability. But what does that mean? Take a look at the definitions below –
Boiling point – the temperature at which a substance changes from a liquid to a gas
Viscosity – the ease with which a substance flows (how runny is it, very viscous means not runny)
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(6 marks)
Flammability- the ease with which something ignites or combusts
1. Where in the fractionating column do you find hydrocarbons with the highest viscosity?
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2. Where in the column do you find hydrocarbons with the highest flammability?
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3. Where in the column do you find hydrocarbons with the highest boiling point?
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4. Where in the column do you find hydrocarbons with the longest hydrocarbon chains?
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You need to remember your chemistry of combustion from Year 8 - The combustion of hydrocarbon fuels releases energy. During combustion, the carbon and hydrogen in the fuels are oxidised. The complete combustion of a hydrocarbon produces carbon dioxide and water, like in this equation –
Knowledge Check
1-2. Give 2 examples of physical properties chemicals have3. Define the word viscosity
4. Describe how viscosity changes as you move up the fractionating column.5. Describe how the flammability of the chemical changes as you move up the fractioning column 6. Describe how carbon chain length affects the boiling point a substance has7. Explain why people burn fuels.
8. Explain why both the carbon and
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hydrogen are said to be oxidised during the combustion of a hydrocarbon fuel.
Target 9 extension task: [check answers in appendix]
The table shows some information about alkanes.
Name Formula Relative formula mass Boiling point in °C
methane CH4 16 –160
ethane C2H6 30 –90
propane 44 –40
butane C4H10 58
pentane C5H12 72 36
hexane C6H14 86 68
(a) Give the formula of propane.
___________________________________________________________________(1)
(b) (i) What happens to the boiling points of the alkanes as the relative formula mass increases?
______________________________________________________________(1)
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(ii) Draw a graph. Plot the points and draw a best fit line.
(3)
(iii) What is the boiling point of butane?
______________________________________________________________(1)
(iv) Show clearly on the graph how you found the boiling point of butane.(1)
(c) Circle which of the following is not an alkane.
C71116 C9H18 C11H24 C24H50
(1)(Total 8 marks)
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Lesson 3 – Cracking and Testing Alkanes and AlkenesRecall
1. Describe the effect of increasing temperature on the rate of a reaction.2. Define the term “reversible reaction”.
3. Give the pH of a strong alkali.
4. Complete the equation: Lithium oxide + sulfuric acid
5. State which part of the fractionating column is the hottest.6. Define the term “hydrocarbon”.
7. Give the name for a positive ion and the name of the electrode it is attracted to.8. Draw the electron configuration of chlorine and sodium, show the electron transfer with an arrow and then draw the ions produced.
Alkanes vs Alkenes
So far, we have learned about hydrocarbons called alkanes. They have a general formula of CnH2n+2, they only contain single bonds and each carbon atom is bonded to as many other atoms as possible, which is why we refer to them as saturated hydrocarbons.
This is butane.
You can tell that the bonds are all single in butane because they are all single lines.
Alkenes are hydrocarbons that contain a double bond. This makes them more reactive than alkanes.
This is butene.
The double bond is shown as a double line. There is only one double bond in alkenes.
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Because alkenes contain a double bond, each carbon is not bonded to the maximum number of other atoms, so alkenes are referred to as unsaturated hydrocarbons.
Polymers and Chemical Production
Ethene is the shortest alkene. It is also one of the most useful because it is used to make the plastic polythene, which is used to make plastic bags and plastic bottles. In order to make polythene, the double bond in the ethene is broken and then they are joined together – this process is called polymerisation and polythene is an example of a polymer.
Several shorter alkenes are also the starting materials for the production of many chemicals.
Keyword Comprehension Task
1. Which type of hydrocarbon is saturated?
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2. Which type of hydrocarbon contains a double bond?
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3. How can you tell from a diagram that there is a double bond?
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4. Which alkene is the shortest?
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5. What is the name for the substance produced when alkenes are joined together?
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Cover Write Check Task
These are the key facts that you need to know about alkanes and alkenes. Learn them off by heart, cover write check them on the next page and then answer the questions.
AlkanesContains only single bonds
Saturated
AlkenesContains a double bond
Unsaturated28
Alkanes Alkenes
Alkanes Alkenes
Alkanes Alkenes
Mini Test
1. Which hydrocarbon has only single bonds?
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2. Which hydrocarbon is unsaturated?
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3. Which bonds are found in alkenes?
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4. Which hydrocarbon is saturated?
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5. Which bonds are found in alkanes?
_____________________
6. Which adjective would be used to describe an alkene?
_____________________
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Testing for Alkenes
Misconception Warning!Do not mix up colourless and clear: they have different meanings.
Colourless is when a substance has no colour. Clear is when a substance is transparent.
This is a red, but clear liquid.
We can use bromine water to distinguish between alkanes and alkenes. Bromine water is orange. If an alkane is added to bromine water, it stays orange. If an alkene is added to bromine water, it will change to colourless.
Addition of Bromine Water:
Practical Activity
Use bromine water to distinguish between an alkane and an alkene.
Observations:
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Cracking
The fractional distillation of crude oil produces alkanes that are different lengths. The shorter alkanes are in high demand because they are used as fuels, but the longer alkanes are not in very high demand and therefore there is a large surplus (left over amount) of long alkanes.
To produce more short alkanes, for fuels, and alkenes, to make polymers, we can crack the long alkane chains. This process is called cracking.
Cracking is an example of thermal decomposition. This is when you heat up a substance to get it to break into smaller parts.
There are two methods of cracking:
Catalytic Cracking: heat the alkanes to vaporise them and then pass them over a hot catalyst.
Steam Cracking: heat the alkanes to vaporise them, mix them with steam and then heat them to very high temperatures.
Balancing Equations
Because cracking is a chemical reaction, there will be the same number of carbon and hydrogen atoms in the reactants and products.
The equations for these reactions should be balanced in the same way as any other reaction (by adding big numbers in front of the chemicals).
Worked Example (to go through with your teacher):
C14H30 ------> C6H14 + C4H8
C = C =
H = H =31
Balancing Equations Task
1. C18H38 ------> C12H26 + C3H6
C = C =
H = H =
2. C20H42 ------> C12H26 + C2H6
C = C =
H = H =
3. C18H38 ------> C10H22 + C4H8 + C2H4
C = C =
H = H =
4. C25H52 ------> C11H24 + C4H8 + C3H6
C = C =
H = H =
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Knowledge Check
1. Give the name of the hydrocarbon that contains a double bond.2-4. Describe the test to see if a hydrocarbon is an alkene or alkane and how you would interpret the results.
Test:
Result for alkane:
Result for alkene:
5. Name the substance produced when alkenes are joined together.6. Define the term “cracking”.
7. Name the two types of cracking.
8. Balance this equation: C25H52 ------> C13H28 + C4H8
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Target 9 extension task: [check answers in appendix]
Q3.
(a) The table shows information about two alkenes.They are named in the same pattern as alkanes. Complete the table to show the names and structures of these alkenes.
(2)
(b) (i) Ethene is an unsaturated compound. State what is meant by unsaturated.
(1) ..............................................................................................................................................(ii) Describe what is seen when ethene is passed into bromine water.
(2) .............................................................................................................................................. .............................................................................................................................................. ..............................................................................................................................................
(c) Alkenes can be obtained by cracking some fractions obtained from crude oil. Explain what is meant by cracking.
(2) .............................................................................................................................................. .............................................................................................................................................. ..............................................................................................................................................
(d) (i) Complete the sentence by putting a cross ( ) in the box next to your answer. Molecules of ethene are reacted together to form poly(ethene). The reaction taking place is
(1) A combustion B photosynthesis C decomposition D polymerisation
(ii) Poly(ethene) is used to make plastic carrier bags. Many of these bags are put into landfill sites.
Explain why the presence of waste plastic in landfill sites causes problems.(2)
.............................................................................................................................................. .............................................................................................................................................. .............................................................................................................................................. ..............................................................................................................................................
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..............................................................................................................................................(Total for Question = 10 marks)
Lesson 4 – Alkenes and ReactionsRecall
1. Describe the reaction of sodium with cold water.2. Explain why ions are stable.
3. State the general formula for alkanes.
4. Describe the trend in reactivity in group 7 of the periodic table.5. Give the name of the hydrocarbon that contains a double bond.6-8. In electrolysis, ions become atoms. Draw an aluminium atom and an aluminium ion and explain how the ion would become the atom. (aluminium atoms have 13 electrons)
Alkenes Comprehension Task
Read the information then answer the questions.
We learned some of the basic ideas about alkenes in our previous lesson and discovered that they were hydrocarbons that contained a double bond. A series of hydrocarbons, such as alkenes, is known as a homologous series.
The double bond is the feature that gives alkenes their unique properties. The feature that gives the members of a homologous series a particular property is known as its functional group. It is therefore correct to say that the functional group of alkenes is the C=C bond.
The general formula for alkenes is Cn2n, and therefore the number of hydrogen atoms in each alkene is double the number of carbon atoms.
1. What is the name given to a series of hydrocarbons, such as alkenes?35
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2. What is the name given to the feature of a series that gives it its unique properties?
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3. What is the functional group of alkenes?
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4. What is the general formula of alkenes?
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5. What is the ratio of carbon atoms to hydrogen atoms in an alkene?
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Task
Complete the structure and molecular formula for each alkene.
Challenge: write out the structural formula for each alkene
Alkene Displayed Structure Molecular Formula Structural FormulaEthene
Propene
CH3CH=CH2
Butene
C4H8
Pentene
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Addition Reactions
The double bond makes alkenes more reactive than alkanes. Most of these reactions are addition reactions. The double bond is broken open and then atoms are added onto the carbon atoms.
Reactions with Halogens
An example of an addition reaction is the reaction with bromine water that was introduced in our previous lesson. This is used to tell the difference between alkanes and alkenes because only alkanes are able to react with the bromine, due to their double bond.
colourless orange colourless
All alkenes react with all halogens in this manner.
For example, this is the reaction of butene with iodine:
Reactions with Hydrogen and Water
Read the information and complete the table about each reaction.
Hydrogenation
Alkenes react with hydrogen in a process called hydrogenation. This only happens at 150⁰C in the presence of a nickel catalyst. Hydrogenation converts unsaturated hydrocarbons (alkenes) into saturated hydrocarbons (alkanes).
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ethene water ethane
Hydration
Alkenes react with steam in a process called hydration. This only happens at high temperatures and pressures and in the presence of a concentrated phosphoric acid catalyst. Hydration converts alkenes into alcohols.
ethene water ethanol
Process Necessary Conditions (Including the Catalyst Required)
Product of the Process
Hydrogenation
Hydration
Misconception Warning!Hydrogenation is the addition of hydrogen. Hydration is the addition of water.
Reactions with Oxygen
Alkenes will also burn in oxygen, like alkanes do. However we do not often burn alkenes as fuel, for two reasons:
1. Alkenes tend to burn in air with smoky flames due to incomplete combustion.
2. Alkenes are very valuable as they can be used to make polymers or as a starting material for many other chemicals.
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Demonstrating Understanding of Addition Reactions
Answer the following questions:
1. Alkenes are very reactive and do addition reactions. What is an addition reaction?
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2. Write equations for the following addition reactions, showing the displayed formula for each chemical:
a) butene + H2
b) propene + H2O
c) ethene + Br2
d) propene + I2
e) pentene +Cl2
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Knowledge Check
1. State what is added during a hydration reaction?2. Explain why alkenes are more reactive than alkanes.3. Give the general formula of alkenes.
4. Describe what you would see during a reaction between an alkene and bromine water.5. State what is added during hydrogenation.6. Explain why alkenes are not burned as fuels.7. State the functional group of alkenes.
8. Describe the conditions needed for hydrogenation to occur.
Target 9 extension task: [check answers in appendix]
Q1. The molecules of three organic substances A, B and C are shown in Figure 6.
Figure 6
(i) A small volume of bromine water is added to each of the substances A, B and C and the mixtures shaken.
Explain why A and B decolourise bromine water but C does not.(3)
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(ii) Ethane, C2H6, is a hydrocarbon.
Draw a molecule of ethane showing all covalent bonds.(2)
(iii) State why ethane is described as a hydrocarbon.
(2)
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Q2. Butene reacts with steam to produce butanol.
C4H8 + H2O → C4H9OH
What type of reaction takes place between butene and steam? (1)
A addition
B dehydration
C neutralisation
D substitution
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Lesson 5 – Alcohols and Carboxylic AcidsRecall
1. Describe the process of cracking.
2. Methane (CH4) is a simple covalent molecule. Draw a diagram showing the covalent bonds between its outer shell electrons.(it is easier if you draw the atoms separately before trying to draw them together)
3. State the pH of a neutral substance.
4. Explain why there is a displacement reaction between calcium oxide and sodium.5. Explain why carbon cannot be used to extract aluminium.6. Describe the arrangement and movement of particles in a gas.7. Explain why the carbon dioxide concentration of the early atmosphere decreased when plants evolved.8. State the equipment needed to separate a mixture of sand and water.
Alcohols
Alcohols contain oxygen so they are not hydrocarbons. Their names and structures follow a similar pattern to alkanes and alkenes and they are therefore another type of homologous series. Their functional group is –OH.
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Complete the table of alcohols
Alcohol Displayed Structure Molecular Formula Structural FormulaMethanol
CH4O
Ethanol
CH3CH=CH2
Butanol
C4H10O
Making Ethanol
Complete the process using the keywords in the box below:
Ethanol is made by the _______________ of sugars in these conditions:
The sugars are _______________ in water _______________ is added The mixture is kept in a warm place at about _______________ _______________ is kept out of the mixture.
Uses of Alcohols
Underline the uses of alcohol in this paragraph:
Alcohols can be used as fuels – camping stoves often use alcohols as fuels and a small percentage of UK petrol is alcohol. Alcohols are very good solvents – many liquid medicines and perfumes are produced using alcohol because they do not dissolve in water. Alcohols are also used to make alcoholic drinks – the type of alcohol depends on the crop that is fermented: apples are used to make cider, grapes are used to make wine and malted barley is used to make beer.
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dissolved air fermentation yeast 30⁰C
Combustion of Alcohols
Alcohols burn well in oxygen – if there is a good supply of oxygen, complete combustion takes place to form carbon dioxide and water.
These combustion equations are NOT balanced. Balance them:
ethanol + oxygen carbon dioxide + water
C2H5OH + O2 CO2 + H2O
propanol + oxygen carbon dioxide + water
C3H7OH + O2 CO2 + H2O
Reactions with Sodium and Water
When alcohols react with sodium, hydrogen is formed.
Suggest what you would see during this reaction.
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Alcohols do not react with water, but small alcohol molecules do dissolve in water to form a pH 7 solution. Most other organic compounds do not mix with water and instead form two layers, which are made up of a layer of the organic compound that is usually on top of the layer of water.
This is a picture of an alcohol drink mixed with water. Explain what the shadow on the picture shows:
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Carboxylic Acids
While complete combustion of alcohols produces carbon dioxide and water, leaving alcohols standing in air leads to mild oxidation and the formation of carboxylic acids. This is another homologous series, with the functional group –COOH.
Ethanol is an alcohol, when it is left to stand in air it forms ethanoic acid (vinegar). If a bottle of white wine was left in air, the ethanol inside would be oxidised to form ethanoic acid and white wine vinegar would be produced.
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Complete the table of carboxylic acids
Carboxylic acid
Displayed Structure Molecular Formula Structural Formula
Methanoic acid CH2O2
Ethanoic acid CH3COOH
Butanoic acid C4H8O2
Properties and Reactions of Carboxylic Acids
Read the information and answer the questions:
Carboxylic acids dissolve in water to form acidic solutions. Acids are substances that produce H+ ions: carboxylic acids are weak acids because they are only partially ionised and produce fewer H+ ions when in aqueous solution than an acid such as hydrochloric acid. As they are only weak acids, they do not cause us any harm when we eat or drink them in small amounts.
Carboxylic acids react with carbonates to form salt, water and carbon dioxide. This reaction would be very slow due to the weakness of these acids.
Carboxylic acids react with alcohols, in the presence of an acid catalyst, to form compounds called esters. Esters have the functional group –COO– and are found in nature: they cause the smell and taste of fruit. We also use them as flavourings for food and drink or to make perfumes.
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Ethanol and ethanoic acid can be added together to produce ethyl ethanoate (an ester) and water.
Ethyl ethanoate is the solvent used to make nail varnish, which is why it has such a distinctive smell.
1. Why are carboxylic acids weak?
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2. What would you expect to see during a reaction between a carboxylic acid and a carbonate? How might it be different from the reaction between hydrochloric acid and a carbonate?
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3. Which homologous series has the functional group –COO–?
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4. Describe some of the uses of esters.
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5. Look at the reaction between ethanoic acid and ethanol shown above and suggest why this type of reaction might be referred to as a condensation reaction.
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Knowledge Check
1. Draw the structure of ethanol.
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2. Give the functional group of alcohols.
3. Give three uses for ethanol.
4. Describe what you would see if sodium was added to ethanol.5. Describe what would happen to the ethanol in wine if it was left to stand in air for a few days.6. Draw the structure of ethanoic acid.
7. Give the functional group of carboxylic acids.8. Describe some uses for esters.
Target 9 extension task: [check answers in appendix]
Q1. (a) (i) Which of the following is the formula for a molecule of butane? Put a cross ( ) in the box next to your answer.
(1) A C3H6
B C3H8
C C4H8
D C4H10
(ii) Draw the structure of a molecule of propene, showing all covalent bonds.(2)
(b) Complete the sentence by putting a cross ( ) in the box next to your answer.Ethanol, C2H5OH, can be converted into ethanoic acid, CH3COOH.In this reaction, ethanol is
(1) A dehydrated
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B neutralised C neutralised D reduced(c) (i) Describe what you would see when solid sodium carbonate is added to dilute ethanoic acid.
(2) .............................................................................................................................................. .............................................................................................................................................. .............................................................................................................................................. ..............................................................................................................................................(ii) When ethanoic acid reacts with ethanol, one of the products is the ester, ethyl ethanoate.
Complete the balanced equation for this reaction.(2)
CH3COOH + C2H5OH → .......................................... + ..........................................
(Total for Question = 8 marks)
Q2.
Ethanol is produced by the fermentation of glucose.
Yeast is needed for the fermentation reaction.
(i) State two other conditions for fermentation.
(2).............................................................................................................................................
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(ii) Complete the sentence by putting a cross ( ) in the box next to your answer.
A dilute solution of ethanol can be converted to a concentrated solution of ethanol by(1)
A filtration
B fractional distillation
C dehydration
D cracking
(iii) Carbon dioxide is the other product of the fermentation of glucose, C6H12O6.
Write the balanced equation for the fermentation of glucose.
(2).............................................................................................................................................
Lesson 6 – Polymerisation and PolymersRecall
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1. Describe the trend in flammability as hydrocarbon chains get longer.2. Name the two products formed when potassium oxide and nitric acid react together.3. State the pH of a strong alkali.
4-5. Draw a chlorine atom and describe how it would become a chloride ion.
6. Explain why potassium must be extracted by electrolysis instead of reduction using carbon.7. Explain why Mendeleev put elements into groups when he made the first periodic table.8. Name the reactants used in the production of esters.
Polymers
Paper clips can be joined together to make long chains. In a similar way, organic molecules can be reacted together to form long chain molecules called polymers. Each molecule that joins together to make a polymer is called a monomer. The exact number of molecules that join together varies, but it is likely to be several hundred/thousand.
Addition Polymerisation
In addition polymerisation the monomers all contain a C=C double bond, which is broken open so that the monomers can join to make a polymer. The name of these polymers is the word poly followed by the name of the monomer in brackets.
For example, ethene molecules can be joined together to form poly(ethene). This is commonly known as polythene and is what plastic bags are made from. The double bond in the ethene is
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broken open, which forms repeating units which can be joined together to form a very long poly(ethene) molecule.
ethene repeating unit poly(ethene)
In additional polymerisation, aside from the polymer, there are no other products formed.
There is another way to draw a polymer, which is shown in the table below.
Complete the table following the pattern shown in the first row:
Monomer Repeating Unit Structure and Name of Polymer
Uses
ethene
Plastic bags, crates and boxes
chloroethene
Water pipes and coatings for window frames
propene
Carpets, crates and boxes
tetrafluoroethene
PTFE tape (used by plumbers) and non-stick coating in frying pans
.
Condensation Polymers
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Condensation polymerisation involves monomers with two functional groups joining together to make a polymer. As the monomers join together, water is released, which is why the reaction is referred to as condensation polymerisation.
Polyesters are made using condensation polymerisation. They are used to make many different fabrics and cushioning materials. To make polyesters, molecules with two carboxylic acid functional groups react with molecules with two alcohol functional groups. When each carboxylic acid group reacts with an alcohol functional group to form an ester linkage (–COO–) and the reaction also gives off water.
The diagram below show what happens in the formation of an ester linkage:
To make a diagram of polyester production simpler, we can represent the section between the two functional groups as a shape on the diagram:
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Another group of molecules that are produced by condensation polymerisation are polyamides. These are commonly used in textiles, the automotive industry, kitchen utensils and sportswear. Polyamides are produced when molecules with two carboxylic acid functional groups react with molecules with two amide functional groups (–NH2). They form amide linkages (–CONH–) and also give off water.
Understanding Condensation Polymers
1. What does the word condensation refer to in the term condensation polymerisation?
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2. How do the monomers in condensation polymerisation compare to those in addition polymerisation?
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3.
Draw the repeating unit for this polymer:
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Biochemistry
There are many naturally occurring polymers that are essential to life, including proteins, starch, cellulose and DNA.
Proteins
Proteins are made of long chains of amino acids.
Amino acids contain two different functional groups:
Carboxylic acid (–COOH), and Amine (–NH2)
The general structure of amino acids is shown in the diagram below. There are 20 amino acids that are essential to life, they all have the same functional groups, but the variable group changes in each amino acid. Different amino acids can be joined together in the formation of proteins.
Amino acids join together in condensation polymerisation reactions to form polypeptides. Polypeptides are the folded into specific 3D shapes to form proteins.
Water is released and a peptide bond is formed between the amino acids.
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Starch and Cellulose
Starch and cellulose are both polymer chains made from the monomer glucose. The glucose molecules are joined differently in each polymer, which is why they have different properties. Starch, cellulose and glucose are all carbohydrates and are made of carbon, hydrogen and oxygen.
DNA
Deoxyribonucleic acid (DNA) is found in the nucleus of cells and is essential for most lifeforms. DNA consists of two long polymer chains that are held together in a double helix. The monomers for DNA are called nucleotides, the sequence of which determines the characteristics of an organism.
There are four different nucleotides and the groups on the side of them attract each other in pairs to hold the two polymer strands together in the double helix. These groups are sometimes abbreviated to A, T, G and C.
Understanding Biochemistry
Use the information from the biochemistry section to answer these questions:
1. What are the monomers that make up:
a) proteins? _______________________
b) starch? ________________________
c) cellulose? _________________________
2. What are carbohydrates made of? Give three examples of carbohydrates.
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3. What does DNA stand for? What are its monomers called and how many types are there?
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Knowledge Check
1. Name the small units that are joined together to make polymers.2. Name the functional group that is found in the molecules that are joined together in addition polymerisation.3. Describe how polyesters are formed.
4. Name the type of polymerisation involved in the formation of polyesters and polyamides.5. Give the functional group of amides.
6. Describe how polypeptides are formed.
7. Name the monomer used to produce starch and cellulose.8. Describe the structure of DNA.
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Target 9 extension task: [check answers in appendix]
Q1. * Polymers are addition or condensation polymers.
Polymers can be formed by using the monomers shown in Figure 12.
Figure 12
Explain, using appropriate monomers from Figure 12, how different polymers can be formed.
(6)
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Appendix 1 – Answers to target 9 questions
Lesson 1 – Mark Scheme
(a) CH4 + 2O2 → CO2 + 2H2O1
(b) toxicaccept causes death
1
acid rain
or
respiratory problemsaccept respiratory problems / asthma
1
global dimming1
(c)
Level 3: A judgement, strongly linked and logically supported by a sufficient range of correct reasons, is given. 5-6
Level 2: Some logically linked reasons are given. There may also be a simple judgement. 3-4
Level 1: Relevant points are made. They are not logically linked. 1-2
No relevant content 0
Indicative content• methane is the best fuel because it gives more energy
per gram than coal, and gives less carbon dioxide per kJ of energy produced
• petrol is best because it being a liquid is easier to handle than gas or coal - although the energy content is lower than the others, it gives out less carbon dioxide than coal
• methane has more energy per gram than coal
• coal produces most carbon dioxide
• coal can produce sulfur dioxide
6
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Lesson 2 – Mark Scheme
(a) C3H8
1
(b) (i) increases / gets larger1
(ii) all 5 points plotted correctlydeduct 1 mark for each incorrectly plotted pointbut ignore –90, 30allow error of one square in any direction
2
smooth line graph
1
(iii) boiling point estimate from their graphallow 2 °C
1
(iv) shown clearly on graphallow just one construction line drawn
1
(c) C9H18
1
[8]
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Lesson 3 – Mark Scheme
Q3.
Answer Acceptable answers
Mark
(a)
Allow CH2=CH2 Allow prope(e)n(e) only
(2)(b)(i) (molecule contains
a) double bond multiple bond(s) ignore spare bonds (1)
(b)(ii) (colour change) from orange (1) to colourless (1)
red/yellow/brown decolorised ignore clear/ discoloured (2)
(c) 1st mark long molecules/ hydrocarbon / alkane/ chain or break down/ decompose/ split (1) 2nd mark into smaller molecules / alkane / alkene / hydrocarbon/ chain or more useful product
(2) (d)(i) D polymerisation (1)(d)(ii) An explanation
linking two of the following poly(ethene) does not rot/biodegrade (1) remains for many years in landfill/ fills up land(fill) (1) (may) harm animals / landfill unsightly (1)
(2)
Lesson 4 – Mark Scheme60
Q1.
Q2.
Lesson 5 – Mark Scheme
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Q1.
Answer Acceptable answers
Mark
(a)(i) D C4H10 (1) (a)(ii)
one C=C in a molecule with three consecutive carbon atoms (1) rest of structure correct, ignore bond angles, conditional on first marking point(1)
allow -CH3
do not allow two C=C in a molecule allow (1) for completely correct dot and cross diagram
(2)(b) C oxidised (1)
(c)(i) A description including two from
effervescence / fizzing / bubbles of gas (1) solid disappears/clears /(colourless)solution formed (1)
ignore cloudy/white ppt /'gas formed'/colour change /name of gas / changes to a liquid (solid/sodium carbonate/it) dissolves (1)
(2)(c)(ii) CH3COOC2H5/
CH3COOCH2CH3 / CH3CO2C2H5 / CH3CO2CH2CH3 / C2H5O2CCH3 / CH3CH2OOCCH3 (1) H2O (1)
allow displayed formulae/ C4H8O2 do not allow formulae ending in – COOH/-COO or any formula that does not show an ester do not allow H2O / H2O /lower case h/HOH maximum (1) if additional incorrect balancing ignore state symbols (2)
Q2.
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Lesson 6 – Mark Scheme63
Q1.
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