CARBON IN LIFE

CARBON IN LIFE

By the end of this chapter, you should be able to:

• Recognize that there is a diversity of carbon compounds in living things and materials derived from living things, and that these may be classified into groups
• Understand that crude oil is a mixture of different alkanes which can be separated by fractional distillation and that these products are used in fuels and to make other useful products
• Know and appreciate that natural gas deposits are found worldwide, that their main constituent is methane and that gas deposits are useful source of fuels and chemical feedstock
• Appreciate that biogas is a carbon-based fuel used for cooking and lighting
• Know some common synthetic and natural polymers and how their properties relate to their uses
• Understand and appreciate that alcohols form a group of compounds of which ethanol is a typical member and has many uses
• Understand how ethanol is made naturally by fermentation of sugars and other organic substances, and be aware of the dangers of abuse of ethanol
• Know the process of making soapy detergents from natural fats and oils and appreciate that soaps are effective in removing only stains
• Know that soap less detergents are made from crude oil and that soap less are better cleaning agents in hard water than the soapy detergents but have a more deleterious effect on the environment 
• Understand how organic compounds can be grouped into homologous series, each of which has similarities in structure and properties

Keywords

• Organic compounds                                           
• Hydrocarbons
• Crude oil
• Petroleum
• Alkane
• Alkene
• Natural gas
• Biogas
• Anaerobic digestion
• Polymerization
• Fermentation
• Alcohol
• Saponification
• Homologous series
• functional group

competency: You will appreciate the diversity of organic carbon compounds including the alkanes, alkenes, alcohols and fatty acids.

Introduction

Did you know carbon is everywhere? Just look around you, what do you see? You will see trees, grass, plants animals. You may also see, substances derived from living things such as plastics, shoes, clothes, paper and glue. Materials such as synthetic fibres and colorful dyes of your clothes, every bite of food you eat, the carpets on your floors and the paint on your walls and the fuels from natural gas. From your first day cloth on earth to your silk-lined coffin, carbon atoms surround you.

Figure 1.1: Examples of carbon-based materials

The materials and their products can be classified into groups with similar characteristics. In this chapter you will explore the carbon-based materials in nature and their products.

1. Carbon based materials

Carbon is the backbone of life. Living organisms and their products consist mostly of carbon-based compounds. Carbon has a great ability to form large, complex, and diverse molecules such as proteins, carbohydrates and vitamins among other molecules that distinguish living matter. How do we know that living things and their products contain carbon? In the next activity you will show that some living things and their products contain carbon.

Activity 1.1 Demonstrating that living things and their products contain carbon

In this activity you will investigate what happens when different natural materials are burned.

What you need

• Spoon
• 2 tea spoonsful of sugar
• Pieces of paper
• Piece of plastic material
• Piece of cloth
• Maize flour
• Pieces of dry wood
• Wool 
• Cotton wool
• Source of heat

Caution: Handle the heating source with care to avoid burns

What to do

1. Place a small quantity of the solid substance on a metallic spoon
2. Direct a flame onto a substance
3. Observe what happens when the material burns and what remains after burning 
4. Repeat the procedure for all the substances

Discussion

1. Write a list of natural materials used in this activity.
2. Identify each material that leaves a black residue after burning
3. Explain why these materials produce a black residue?
4. Name other materials other than those used in the experiment that may produce a black residue.
5.  Deduce the importance of the black residue in showing that natural substances and their products contain carbon

Organic compounds

You may have noticed in activity 1.1 that a black substance was left when the different materials were burnt. The black substance is Carbon. All living and dead plants and animals contain the element, Carbon. For example, wood, glucose, starch, sugar and ethanol are compounds of carbon. The chemicals from which living things and their products are made called organic compounds.

Figure 1.2: Different organic compounds 1

They are compounds that are found in organisms and their products.

Organic chemistry is the study of the compounds of the carbon apart from the oxides and salts.

This includes all the compounds of the carbon except carbon monoxide, carbondioxide, carbonates, there are many common organic substances. Can you identify common organic compounds in our environment? Try activity 1.2.

Activity 1.2 Identifying organic compounds in our environment

What you need

Different materials available in your environment

What to do 

1. In your group, collect and observe different materials around the school
2. Classify them as organic or not organic
3. Make a table showing the organic and not organic substances

Discussion

1. Name the different organic materials you identified
2. On what basis did you classify them as organic?
3. What are the uses of the materials you identified as organic in everyday life?
4. What does the classification tell you about the variety of organic materials in our environment?
5. Write a two-stanza poem praising the variety and importance of organic materials in nature and present it to the whole class in a plenary.

2.  Classifying organic compounds

Figure 1.3 Shows a family of mountain gorillas in a national park located in south western Uganda. Can you identify any similarities or differences between the animals?

Figure 1.3: Family of mountain gorillas in south western Uganda 1

Organic compounds can be classified into groups or families with similarities like those of the mountain gorillas in the figure 1.3. The classes of organic compounds with similar chemical properties are called homologous series. Members of the same homologous series contain the same functional group. A functional group is an atom, group of atoms or bond that determines the properties of an organic compound. In the next activity you will identify the different homologous series and indicate the functional group they contain.

Activity 1.3 Identifying homologous series of organic compounds

What you need

Internet or text books

What to do

1. Work in groups and search for information about homologous series and functional groups.
2. Use the information to respond the tasks that follow

Discussion

1. Draw a table showing 5 homologous series, their functional groups and name two examples of common compounds in the group
2. Give one similarity in the structure among the members of each series you have identified
3. State one difference in the structure of compounds in the same homologous series
4. Discuss how the similarities and differences identified affect the physical and chemical properties of the compounds in the same homologous series.
5. Present your findings to the rest of the class.

Hydrocarbons

You have already leant that there is a vast number of organic compounds in our environment. You have also learnt that organic materials contain carbon as a major element. What other elements do you think are found combined with carbon? Many carbon-based compounds contain carbon and hydrogen as the major compounds. Any organic compound containing only carbon and hydrogen atoms is called a hydrocarbon.

Hydrocarbons are compounds containing carbon and hydrogen only

Hydrocarbons can be classified into alkenes and alkynes. Petrol, diesel and paraffin served at a petrol station (figure 1.4) are examples of hydrocarbons.

Figure 1.4: petrol and diesel are examples of hydrocarbons 1

Hydrocarbons can be either saturated or unsaturated. Saturated hydrocarbons have single bonds (-C-C-) between carbon atoms whereas unsaturated hydrocarbons contain double (-C≡C-) or triple bonds (-C=C-) between the carbon atoms. Because they contain carbon and hydrogen, when they burn, hydrocarbons produce carbondioxide and water. You can demonstrate this in activity 1.4.

Activity 1.4 To show that burning hydrocarbons produces carbondioxide

What you need

• Spirit lamp
• Kerosene
• Glass funnel
• Delivery tube
• Lime water

Caution: The source of heat should be handled with care to avoid burns.

What to do

1. Burn about 20cm³ of kerosene in a spirit lamp.
2. Ensure that the waste gases pass through a funnel into a delivery tube.
3. Arrange the apparatus as shown in the diagram below.

Figure 1.5: Burning hydrocarbons 1

4. Allow the waste gases into a boiling tube containing lime water.
5. Repeat the procedure using diesel.

Discussion 

1. What changes do you observe in the boiling tube A?
2. Explain the observations.
3. How do the products using kerosene and diesel compare?
4. Describe how you can demonstrate that water is one of the products in this activity.

Alkanes

You have already learnt that organic compounds can be grouped into families called homologous series. The simplest family of hydrocarbons is alkanes.

Alkanes are hydrocarbons with single carbon to carbon bond.

The simplest alkane is methane. It contains one carbon surrounded by four hydrogen atoms. Note that the carbon atoms are surrounded by four bonds. The figure 1.6, illustrates the structure of methane.

Methane – a carbon atom                                     model of ethane molecule

Bonded to 4 hydrogen atoms

Figure 1.6: Structures of alkanes 1

Alkanes have a general formula CnH2n+2 where n is the number of carbon atoms in the molecule. n=1,2,3, 4….

Where more than one carbon atoms are involved, the carbon atoms bond to each other and are surrounded by hydrogen atoms. In activity 1.5 you will observe 1.6 and use it as a basis to model structures of different alkanes.

Activity 1.5 Naming and modelling the structure of alkanes

What you need  

• Internet or textbooks
• Manila paper
• Markers of different colours

What to do

1. In your groups, use text books or internet to gather information about the structure and naming of alkanes.
2. Carefully observe how the carbon and hydrogen atoms are connected to each other in figure 1.6.

Discussion

1. Identify the prefixes and names for names for the first four alkanes
2. Use your findings to copy and complete the table below

No. of Carbon atoms	Prefix	Name of alkane
1.	Meth	Methane
2.
3.
4.

3. Draw structures of the named alkanes on a manila paper using different colored markers
4. Using materials in your environment, model the structures of the alkanes you have drawn in 3 above.
5. Display your models for comparison with those of the other members of the class
6. What do the structures you have modelled indicate about the bonding in alkanes?

3.  Crude oil is a mixture of different alkanes

Have you heard that our country Uganda is about to start producing crude oil?

Crude oil deposits were recently discovered in the western Districts of Hoima, Kikuube and Buliisa on the shores of lake Albert. The pictures below show different operations in one of the crude oil exploration sites in the Albertine region of western Uganda during exploration stage.

Figure 1.7: Working on a crude oil mining site near lake albert  1

Crude oil is a mixture of alkanes. In the activity, you will research about the different components that make up crude oil.

Activity 1.6 identifying components of crude oil

What you need

Internet or text books

What to do

In your groups, search for information about crude oil and its components

Discussion

1. Identify the different components of crude oil
2. For the different components identified, find out about their boiling points
3. Arrange you’re your findings in a tabular form and share with the whole class in a plenary
4. What can you conclude from the activity?

Separating components of crude oil

By itself, petroleum is almost useless. However, the different parts (fractions) are among the most useful chemicals in our lives. How do we obtain the fractions from crude oil? You recall from activity 1.6 that the different fractions of crude oil have different boiling points. Petroleum can be separated in to different parts by fractional distillation. Do you remember the process of fractional distillation we studied in senior one? The process involves heating the mixture until it vaporizes and then allowing the vapour to cool until it condenses again. Fractional distillation of crude oil is done in an oil refinery figure 1.8.

Figure1.8: A giant oil refinery in Jeddah Saudi Arabia 1

However, we can simulate the way it is done in industry by carrying out an activity in the laboratory to show how the different fractions are obtained.

Activity 1.7 Simulating the distillation of petroleum in the laboratory

What you need

• Thermometer
• Boiling tube
• Beaker containing cold water
• Source of heat
• Crude oil (you can use engine oil)

Caution: Handle the heat source with care to avoid burns.

What to do

1. Arrange the apparatus as shown in the set up below
2. Heat the crude oil gently at first and collect the first few of the first liquid that collects.

Figure 1.9: Simulating distillation of crude oil  1

3. Keep heating and change the collecting tube
4. Now collect the liquid that distils up to 1500◦C.
5. Again, change the receiving tube and collect the liquid when you heat strongly.
6. Observe the different liquids collected in the different test tubes
7. Try to light each fraction on a spatula end and observe what happens

Discussion

1. Why must the collecting tube be kept in cold water?
2. If you need fuel for your car, why would you prefer to use the first fraction?
3. Why would you prefer to use the last fraction to lubricate your car engine?
4. What can you conclude from this activity about the composition of crude oil?

Oil refining in industry

In the demonstration in activity 1.7, you distilled a sample of petroleum substitute by boiling off each fraction separately. Why do you think this is not suitable for industrial purposes? It would take ages to distil a reasonable number of components! In the refinery, fractional distillation takes place in a fractionating tower (figure 1.10).

Figure 1.10: Industrial fractionating column for refining crude oil  1

In the refining process, the mixture is boiling together but the fractions are condensed at different temperatures at which they boil. You will use activity 1.8 below to explore this process more.

Activity 1.8 Demonstrating petroleum refining in industry

What you need

• Internet or text books
• Manila paper
• Markers of different colours

What to do

In your groups use the internet or textbooks to search for information about distillation of crude oil.

Discussion

1. Using manila paper and markers, draw a setup that can be used to obtain fractions of crude oil in a refinery.
2. On the diagram in (a), indicate the temperature at which each of the fractions can be obtained.
3. Share your finding by displaying your drawing in one part of the class.
4. Compare your diagram with that of your classmates and harmonize as a class about any differences in the setup.

Crude oil fractions are useful

Figure 1.11 below shows road workers laying Asphalt layer on a road under construction in Mbale Uganda. Asphalt is mixture of small stones, sand and bitumen used to make tarmac roads. Bitumen is a fraction obtained from crude oil.                       

Figure 1.11: Workers laying asphalt on a road in Mbale-Uganda  1

There is a large number of products that can be obtained from petroleum. Do you know the use of the different fractions of petroleum? In the next activity, you will explore the different uses of petroleum.

Activity 1.9 Identifying uses of crude oil fractions

What you need

• Internet or text books
• Paraffin
• Diesel
• Petrol
• Tar
• Plastic

Caution:

• Petrol is very flammable and must not be brought close to a source of fire.
• Avoid inhaling the samples as they can be poisonous

What to do

1. Observe the different materials provided in your class carefully and discussion in your groups their use in everyday life.
2. Use the internet or text books to identify other crude oil fractions and their uses

Discussion

1. Draw a table showing the crude oil fractions on one side and their uses on the other side.
2. Briefly explain how the fractions are used in the different uses identified
3. As a group, write an essay detailing why discovery of petroleum in Uganda is a blessing.
4. Read your essay to the whole class in a plenary.

Cracking increases the amount of useful fractions

Did you know that crude oil is one of the most wanted resources in this world? Countries which produce crude oil such as Kuwait are some of the richest! The supply for various fractions of crude oil from refineries is not enough to match with demand. More so, the lighter fractions such as petrol have more demand than rest of the materials. The process of cracking is used to break down longer chain fractions of petroleum into shorter desirable fractions.

Cracking is the process by which big molecules are broken down by heating them as they are passed over a catalyst.

This process takes place at the refinery in a cracking plant (figure1.12).

Figure 1.12: A cracking plant in an oil refinery  1

In the laboratory, we can crack large molecules into smaller ones. Activity 1.10 below demonstrates the process.

Activity 1.10 Demonstrating petroleum refining in industry

What you need

• Paraffin
• Ceramic wool
• Source of heat
• Aluminimum oxide
• Hard boiling tube with cork
• Water bath

Caution: you must take the end of the delivery tube out of the water before you stop heating

What to do

1. Arrange the apparatus as shown in the diagram below

Figure1.13: Cracking paraffin 1

2. Every now and again, move the flame onto the paraffin to ensure that some vapour is passing along the tube.
3. Collect two test tubes of gas

Discussion

1. Briefly describe the observable physical features of the gas produced
2. Explain why at the end of the experiment a gas was formed
3. How does the nature of the gas formed help to explain the importance of cracking?
4. With help of your teacher, discuss other benefits of cracking in addition to increasing the number of useful crude oil fractions.
5.  Natural gas

Do you use gas in your home or school for cooking or heating substances?

Figure 1.14 shows gas in cylinders sold at different petrol stations in Uganda.

Figure1.14: Different brands of cooking gas in uagada1

Where do you think the gas comes from? Gas is an example of natural gas. Natural gas is a fossil fuel, like oil and coal. A fossil fuel is a non-renewable energy source such as coal, coal products, natural gas and crude oil originating from plants and animals that existed in the geological past.

Its main component is methane gas. It is formed from decayed organic material transformed by high temperatures and pressures over millions of years into bubbles of methane gas. Conventional sources are found in underground gas fields or oil fields. Factories such as one shown in figure 1.15 are used in processing the gas.

Figure 1.15: Factory producing natural gas in Morocco  1

Unconventional sources are more difficult to extract because the gas is locked inside the sediment. Natural gas is a fossil energy source that is formed deep beneath the earth’s surface. What more do you know about natural gas? You will find out in activity 1.11 below.

Activity 1.11 Demonstrating petroleum refining in industry

What you need

Internet or text books

What to do

In your groups, search for information about natural gas its composition, source and uses.

Discussion

1. Describe the process of formation and composition of natural gas
2. Identify where natural gas deposits can be found around the world
3. Describe how natural gas can be used in everyday life
4. Report your findings to the whole class in a plenary
5. Natural gas is a clean source of energy. Design stickers that can be used to encourage members of your community to switch to natural gas a better alternative to other energy sources.
6. Biogas 

have you seen the vapour which comes out of a rubbish bin in the morning?

Many of us imagine it is water vapour or even air!

Figure 1.16: Heap of decaying rubbish gives off gas 1

The photograph in figure 1.16 was taken from garbage collection area in Rubaga division, Kampala city.

In truth, the vapour contains many gases including water vapour, carbondioxide, nitrogen and other gases. But the major component of the mixture is methane. Thus, the gas you see on dustbin is Biogas.

Biogas is the mixture of gases produced by the breakdown of organic matter in the absence of oxygen consisting of mainly methane and carbondioxide.

What determines the compositions of biogas? The components of biogas mainly depend on the materials used to make the gas. Thus, biogas may in addition include ammonia and hydrogen sulphide and any other gas. Biogas can be produced from organic raw materials such as agricultural waste, manure, municipal waste, plant material, sewage, green waste or food waste.

Producing biogas

You have learnt the biogas cannot be easily collected when produced in this way. How can we produce biogas and collect it for use? In the activity below, you will design a way of producing biogas and collecting it for domestic use.

Project 1 designing a simple biogas digester

What to do

1. In your groups, plan and design a model of a biogas digester. In your plan include all the materials you will require for production and collection of the gas.
2. Present your plan to your teacher for guidance
3. Use the materials indicated to make the biogas digester and collect a sample of the gas
4. Ask the members of the class to visit your digester and explain your project to them

Discussion

1. Explain the choice of materials used to produce the biogas
2. If needed a constant supply of biogas in your home, what adjustments would make in your biogas digester?
3. How do you know that what you have produced is biogas?
4. Document the whole process leading to the production of biogas in a report.
5. Share your report with the rest of the class in a plenary

Biogas is useful

Biogas is a very useful and affordable gas. But how can it be used? The figure below shows a biogas burner design used by a women’s group in jinja district of Uganda (figure 1.17).

Figure 1.17: Using biogas for cooking 1

The women in the group uses biogas for cooking. Can you think of any other uses of biogas? You will explore more uses of biogas in activity 1.12 below.

Activity 1.12 exploring the uses of biogas

What you need

Internet or text books

What to do

In your groups, use the internet or textbooks to search for information about the different uses of biogas

Discussion

1. Identify the different uses of biogas apart from cooking
2. Explain why is biogas not widely used in Uganda?
3. Draw a poster that can be used to popularize the uses of biogas in Uganda
4. Share your findings with fellow learners by presenting in a plenary

Alkenes

You have already learnt about alkanes. Another class of hydrocarbons containing at least one double carbon to carbon bond in their molecules. Because they have more than one bond between carbon atoms, they are referred to as unsaturated hydrocarbons. They are very useful as starting materials for other products (see figure 1.18).

Figure 1.18: Some products made from alkenes 1

The general formula of alkenes is CnH2n where n indicates the number of carbon atoms in the molecule.

The general formula of alkenes: CnH2n

The first member in the group is ethene. The formula of ethene is C2H4 and the structure is shown below.

Figure 1.19: Structure ethene 1

As you did for alkanes you can model the structure of ethene using locally available materials.

Activity 1.13 modeling the structure of alkenes

You will do this activity in groups

What you need

• Internet or text books
• Common materials in environment
• Manila paper
• Marker

What to do

1. In your groups, use internets or text books to find information about the structure and naming of alkenes.
2. Using manila and markers, draw the structure and name the common alkenes
3. Use commonly available materials in your environment to model the structure of the first two alkenes you have drawn.
4. Display your drawings and models in class for comparison with those of other groups

Discussion

1. Document the procedure you used in the making of the models
2. Explain the choice of materials used in the making of the models
3. How do your models differ from those of other groups?
4. Score your model on a scale of 1-5
5. Explain why you give yourself that score
6. How can you improve your model so that it demonstrates the structure of alkenes better?

Properties of alkenes

Alkenes like any homologous series have some characteristic physical and chemical properties. What determines the physical properties of alkenes? Apart from the functional group, the length and structure of the alkene determines its physical properties. In the next activity you will explore the physical and chemical properties if alkenes.

Activity 1.14 Exploring the physical properties of alkenes

What you need

Internet or text books

What to do

1. In your group, search for information about the different physical properties of alkenes
2. Discuss within your group and compile a report of your findings

Discussion

1. Outline the physical properties of alkenes under the following headings

1. Solubility in water
2. Solubility in organic solvents
3. Melting point and boiling point
4. Physical states

2. Explain how the structure of the alkene affects its physical properties
3. Present your findings to the rest the class

Chemical properties of alkenes

Are you aware that many materials used in everyday life come from alkenes? Alkenes are very reactive hydrocarbons. Their high reactivity is the reason they are commonly used as feed stock for manufacturing industries. Very many products are made using alkenes as starting materials. In addition, alkenes can be used as fuels. In the next activity, you will investigate some chemical properties of alkenes.

Activity 1.15 Demonstrating the reactions of alkenes

What you need

• Hexene (any other liquid alkene)
• Bromine water
• Source of heat
• Dropper
• 2 Test tubes
• Spatula

Caution: hexene should be handled with care because it is flammable

What to do

1. Take a little of hexene on a spatula head and introduce it to a flame. Note your observation.
2. Transfer about 2cm3 of hexene into a clean test tube and add bromine water. Note your observations.

Discussion

1. State your observations in 1 and 2.
2. Explain the observations in 1 and 2.
3. Using internet or text books respond to the following tasks about alkenes

1. Write equation for the reaction that took place in 1 and 2.
2. Discussion the reaction between alkenes and hydrogen gas
3. Explain the process of polymerizing alkenes using ethene as an example
4. Document and present your findings to the whole class.

1.6 Polymers

Let us inquire into the chemical nature of the materials shown in the pictures below that we use frequently in our daily life. If you observe the materials carefully, what do the different materials have in common? On the first sight, you can say they are all brightly colored.

          Plastic goods Clothes Toys

Figure 1.20: Different materials 1

However, at molecular level, they all have a common special feature. All of them are made up of large molecules arranged in the form of long chains. Another specialty is that most of those long chain molecules are composed of repeating small molecular units. Thus, the molecules from which they are made are called polymers. Do you recall what you learnt about polymers in senior one? In activity 1.16 you will re-examine the structure of polymers by making models.

Activity 1.16 Modeling the structure of polymers

What you need

• Suitable materials from the environment
• Internet or text books

What to do

1. In your groups, use the internet or any suitable text book to collect information about the structure of polymers
2. Select materials in the environment for use in modeling the structure of polymers

Discussion

1. What materials did you use to represent monomers in your model?
2. Justify the choice of materials in the used to design the model
3. Document the process followed making the model and present it to your teacher.
4. Share your model with the rest of the class.

Natural and synthetic polymers

Look at the beautiful cotton and sisal plants below. What are they used for? Cotton and sisal contain cellulose threads which can be used for different functions including clothes and bags. Cellulose is a natural polymer because it is obtained from plants which grow naturally. Can you think of other natural polymers?

Figure 1.21: Cotton and sisal contain cellulose a natural polymer1

Figure 1.22 shows nylon and polythene which are produced from the industry. They are artificial polymers.

Figure 1.22: Nylon and polytene are natural polymers1

Do you know the monomers which make up the polymers? In activity 1.17 you will classify some natural and artificial polymers and state the monomers from which they are formed.

Activity 1.17 identifying polymers and their monomers

What you need

Internet or text books

What to do

In groups, use the internet or text books to search information about natural and artificial polymers.

Discussion

1. Identify 4 natural and 4 artificial polymers
2. State the monomers from which the polymers are obtained
3. Identify the uses of the named polymers in everyday life
4. Tabulate your findings and present them in class for discussion.

The use of polymers is related to their properties

You have learnt about the natural and artificial polymers and their use in everyday life. Why are they commonly used in the different ways? When you observe different polymers, you realize that their functions are based on some special properties that they possess. Figure1.23 shows different cotton fabric designs. What are the uses of cotton fabric?

Figure 1.23: Different designs of cotton fabric 1

Cotton fabric can be used to make bed sheets, shirts, dresses among others. Do you know why it is used for those functions? One reason is because it can retain heat. In the next activity you will explore the properties that make different polymers suitable for particular uses.

Activity 1.18 Relating properties of different polymers to their uses

What you need

• Plastic pipe
• Sisal rope
• Plastic cup/basin
• Cotton thread
• Paper
• Rubber shoe
• Nylon fishing net

What to do

In your group, observe the different polymer materials provided and respond to the following questions.

Discussion

1. What is the use of the polymer in each case?
2. Identify the prominent properties of the polymers provided
3. For each polymer, explain the relationship between the prominent properties and use.
4. What can you conclude from the activity?
5. Alcohols

What comes to your mind when you hear the word alcohol? Probably it is the men or women who drink themselves silly in your village. However, ethanol is not the only commonly used alcohol. Glycerine, is commonly used in Uganda for hair treatment. (see fig. 1.24B)

      1.24A: People drinking Ajono a common alcohol in                   1.24B: Glycerol (glycerine) is a commonly used alcohol to 

Eastern Uganda  1                                                                                                  treat hair

The alcohol (ethanol) that people drink is one example of the group of compounds called alcohols or alkanols.

Alcohols are organic compounds containing at the least one hydroxyl (-OH) group in their molecules.

They can be viewed as alkanes where one hydrogen was replaced by a hydroxyl (-OH) group. Alcohols have a general molecular formula as CnH2n+1OH. where n=1,2,3…

In the next activity you will write the structures and name common straight chain alcohols.

Activity 1.19 Representing structures and naming alcohols

What you need

Internet or textbooks

What to do

In your groups, use the internet or textbooks to search for information about the structural formula and naming of alcohols.

Discussion

1. Write molecular formula and draw the structural formula of the first 4 straight chain alcohols.
2. Name the alcohols whose structures you have drawn.
3. Using materials available in your environment, model the structures to represent the first 2 alcohols in the series.
4. Document and present your findings to the rest of the class.

Properties of alcohols

Alcohols like any other organic compound have properties related to their functional group. In the activity below, you will explore the physical properties of alcohols.

Activity 1.20 physical properties of alcohols

What you need

• Methanol
• Ethanol

• Propanol
• Glycerol
• Ceramic slab
• Dropper
• 4 test tubes

What to do

1.separately put a drop of the alcohol on a dry ceramic slab and wait for 3 minutes. Note your observations.

2. put 2cm3 of each alcohol in a test tube and add some water. Shake the mixture well and note your observations.

3. observe the colours of the alcohols provided carefully. Note your observation.

Discussion

1. State your observation in 1, 2 and 3.
2. What is the colours of the alcohols provided?

1. Separately put a drop of the alcohol on a dry ceramic slab and for 3 minutes. Note your observations.
2. Put 2cm³ of each alcohol in a test tube and add some water. Shake the mixture well and note your observations.
3. Observe the colors of the alcohol provided carefully. Note your observation.

Discussion

1. State your observations in 1,2 and 3.
2. What is the of the alcohol provided?
3. Comment on the volatility of the different alcohols provided.
4. What does the observation about the volatility of the alcohols indicate about the boiling points of the alcohols?
5. Comment on the solubility of the alcohols in water.
6. What does the physical state of the alcohols provided indicate about the general physical state of alcohols?

Chemical properties of alcohols

The chemical properties of alcohols are determined by functional group. In the activity below, you will out some properties of alcohols using ethanol as an example. 

Activity 1.21 Exploring chemical properties of alcohols

What you need

• Ethanol
• Spatula
• 4 test tubes
• Acidified potassium dichromate
• Acetic acid
• Anti- bumping stones
• Test tube holder
• Litmus paper

What to do

1. Drop a litmus paper into a test tube containing ethanol. Note your observation.
2. Add about 5cm3 of ethanol into a test tube and add an equal volume of water. Shake the mixture and leave it to stand in a rack. Note your observations.
3. Place a few anti bumping stones into a boiling tube. Add ethanol, acetic acid and a few drops of sulphuric acid. Heat the mixture carefully and try to smell the product. Note your observations.
4. Heat a mixture of ethanol and acidified potassium dichromate in a boiling tube. Note your observations.

Discussion

1. What did you observe in 1,2,3 and 4?
2. Explain your observations in 1,2,3 and 4.
3. What can you conclude from the observations?

8.  Production of ethanol by fermentation

Ethanol is produced industrially by fermentation.

Fermentation is an anaerobic chemical change buy which carbohydrates are converted into ethanol and carbondioxide in presence of yeast.

The raw materials for fermentation are a carbohydrate or sugar. Sorghum, millet, cassava, cane sugar, and ripe bananas are commonly used in Uganda. When yeast is added it feeds on the sugar in the absence of oxygen to form ethanol and carbondioxide. In the first stage of the process, the carbohydrate is first converted into simple sugars by the enzyme amylase found in yeast.

C12H22O11(S)+H2O(C)2C6H12O6(S)

Fermentation is an anerobic chemical change by which carbohydrates are converted into ethanol and carbondioxide in presence of yeast.

The raw materials for fermentation are a carbohydrate or sugar. Sorghum, millet, cassava, cane sugar, and ripe bananas are commonly used in Uganda. When yeast is added it feeds on the sugar in the absence of oxygen to form ethanol and carbondioxide. In the first stage of the process, the carbohydrate is first converted into simple sugars by the enzyme found in yeast.

C12H22O11(S)+H2O(C)2C6H12O6(S)

Then another enzyme called zymase converts the glucose to ethanol.

C6H12O6(S)2CO2(g)+2C2H5OH(l)

The ethanol produced in this way has an alcoholic content of less than 15%. To increase the alcohol content, the raw ethanol is distilled.

Activity 1.22 To prepare ethanol in the laboratory through fermentation

What you need

• Conical flask (100 cm³)
• Boiling tube,
• Measuring cylinder (50 cm³)
• Cotton wool,
• Sticky labels,
• Water
• Source of heat
• Thermometer
• Glucose (5 g)
• Yeast (1 g)
• Limewater

Caution: to be performed under the supervision of teacher

What to do

1. Put 5 g of glucose in the conical flask and add 50cm³ of warm water (about 40◦C). swirl the flask to dissolve the glucose.
2. Add 1 g of yeast to the solution and loosely plug the top of the flask with cotton wool.
3. Wait for two days while fermentation takes place.

figure 1.25: Fermentation process of glucose 1

4. Remove the cotton wool and pass the invisible gas into the boiling tube containing limewater. Take care not to pour in any liquid as well.
5. Gently swirl the limewater in the boiling tube and note the change.
6. Replace the cotton wool on the of the flask. 
7. Remove the cotton wool and note the smell of the solution.

Discussion

1. How do you know fermentation is taking place?
2. Limewater test is used for the production of which gas?
3. Which enzyme is responsible for the fermentation in yeast?
4. Write down the reaction for the fermentation of glucose.

Project 2 making alcohol by fermentation locally

What to do

1. Visit one knowledge elder in your community and obtain information on how to make alcohol by fermentation locally.
2. Document the steps as narrated and share them with your teacher.
3. Prepare a sample of alcohol using locally available materials
4. Share your product with your teacher for assessment

Discussion

1. Present the steps used in making the alcohol to the rest of the class
2. Discuss the choice of materials for preparing the alcohol
3. How can you ensure that the alcohol you have made is preserved?

Ethanol is useful compound

Earlier in this chapter, we looked at alcohols as one of the groups of organic compounds but we never discussed its use in everyday life. The figure below shows ethanol being used in sanitizers to kill germs.

Figure 1.23 Physical properties of alcohols1

Do you know any other use of ethanol other than making sanitizers? In the next activity you will find out other uses of ethanol.

Activity 1.23 Physical properties of alcohols

What you need

Internet or any text books

What to do

In your groups, search for information about the uses of ethanol

Discussion

1. Identify the uses of alcohol
2. What makes ethanol suitable for the uses identified?
3. What conclusions can you draw from the activity?

Ethanol in alcoholic drinks

Have you seen people consuming ethanol? People consume ethanol in different forms as their favorite drink. The figure below shows the different alcoholic drinks.

Figure 1.27: Different alcoholic drinks in uganda1

Alcoholic drinks are dilute solutions of ethanol in water. The ethanol in the drinks is made by the process of the process of fermentation as earlier discussed. Even just one drink of ethanol impairs your coordination and judgement. According to police reports of the last five years in Uganda, it is estimated that alcohol a cause of over 40% of all car accidents in the country. Do you think people should continue drinking alcohol? In the activity below, you are going to explore the effects of alcohol.

Activity 1.24 Exploring the effects of drinking alcohol

What you need

Internet or any library resources

What to do

In your groups, search for information about the effects of ethanol

Discussion

1. Identify the effects of alcohols in human beings
2. How can the effects of alcohol be controlled?
3. In your groups organize a debate to discuss the effects of alcohol. One group should argue for and the other against the motion to use or not to use alcohol.

Carboxylic acids

You have eaten a pineapple, orange or lemon. While they are sweet, they have a sour acidic taste.

Figure 1.28: Pineapples, oranges and lemons have an acidic taste 1

Fruits and other materials taste sour because they contain acids. The acids that are derived from natural substances are called organic acids. The scientific name of the acids is carboxylic acids or alkanoic acids. Carboxylic acids have a general molecular formula CnH2n+1COOH. Where n is the number of carbon atoms in the molecule. n=0,1,2,3, …

The name of a carboxylic acid is obtained by replacing the ending “-e” in the name of the appropriate alkane with “-oic acid.”

Activity 1.25 Representing and naming organic acids

What you need

Internet or text books

Materials from the environment

What to do

1. In your groups, search for information about the naming   drawing the structure of organic acids.
2. Select suitable materials in your environment for modeling organic acids

Discussion

1. Identify and name the first 2 organic acids
2. Draw the structure of the acids you have named in your book
3. Represent the structures you have drawn as models using materials from the environment.
4. What is special about the structures of organic acids?
5. Present your findings to the rest of the class discussion

Some properties of organic acids

The properties of organic acids are related to their structure. One important property of organic acids is the reaction with carbonates and hydrogen carbonates to produce carbondioxide. The next activity demonstrates this property.

Activity 1.26 Testing for the acid group in organic acids

What you need

• Test tube
• Dropper
• Distilled
• Ethanoic acid
• Sodium bicarbonate

What to do

• Take a clean test tube. Put ethanoic acid (500 mg) in it.
• Add about 5cm³ of distilled water to dissolve the acid.
• Add half a spatula end full of sodium bicarbonate. What do you observe?
• Bring a burning match stick near the mouth of the test tube. What happens?
• Pass the evolved gas through the lime water. What do you observe and

Figure 1.29: Effort of acids on carbonates 1

Discussion

1. Explain the observations in the experiment
2. Write the equation involving between ethanoic acid and sodium bicarbonate.
3. Write the equation involving reaction between carbondioxide and limewater.
4. How is the reaction between sodium hydrogen carbonate and organic acids useful in everyday life.

Reaction with alcohols

There are many sweet-smelling substances in everyday life. The figure below shows some sweet-smelling flowers.

Figure 1.30: Different flowers smell nice because they contain esters1

The different flowers smell nice because they contain esters. These esters contained in flowers and other materials and other materials are naturally occurring. However, you can make esters in the laboratory by reacting acids and alcohols as demonstrated in the next activity.

Activity 1.27 showing that the reaction between an alcohol and organic acid produces an ester.

In this activity you will make an ester by the reaction between an organic acid and an alcohol

What you need

• Test tube
• Source of heat
• Concentrated sulphuric acid
• Water bath
• Ethanol
• Acetic acid

Caution: concentrated sulphuric acid is corrosive and must be handled with care

What to do

1. Add 2cm³ of ethanol to 1cm³ of concentrated ethanoic acid in a test tube
2. Then add 3 drops of concentrated sulphuric acid to act as a catalyst
3. Warm the mixture gently in a hot water bath for 5minutes
4. Pour the mixture into a small beaker containing sodium hydrogen carbonate solution and stir well. Note the smell.

Discussion

1. Why do you need to add the mixture to sodium hydrogen carbonate?
2. How do the products smell compare with that of the reactants?
3. Explain the importance of this reaction in everyday life.

Soapy detergents

The figure below shows different soaps in Uganda. Some are homemade while others are made from the factory. Why do we need to make soap? We need soap for various cleaning purposes in our everyday life.

Figure 1.31: Different soapy detergents 1

Activity 1.28 understanding soapy detergents

What you need

Internet or textbooks

What to do

In your groups, use internet or textbooks and search information about the nature and composition of soap

Discussion

1. What is soap?
2. Describe the nature of soap
3. What raw materials are used to make soap?
4. What other materials can be added to soap to improve its properties?
5. What differentiates toilet soap from washing soap?

The process of making soapy detergents

We all use soap to clean our utensils and wash our clothes. Many times, the soap comes in bars and pieces. Do you how the is made? A number of soap industries exist in Uganda. They produce most of the bar soap we use. The basic process of making soap is basically the same whether the soap is made at home or in industry. The process of making soap using an alkali and fat/oil (ester) is known as saponification. You can prepare a sample of soap in class using locally available materials.

Activity 1.29 making soap at home

What you need

• Vegetable oil(25cm³)
• Solution of ash filtrate from banana peelings(30cm³)
• Common salt (15g)
• Kettle
• Heat source

Caution: handle the source of heat with care to avoid burns

What to do

1. Burn two basinful of banana peelings to obtain ash.
2. Collect the ash formed, add 2litres of water, shake and filter with a piece of cloth. Heat to evaporate the water to about half the volume.
3. Boil the filtrate (solution obtained) with 1litre of vegetable oil for about 40mintues while continuously stirring with a wooden rod and each time adding some little to replace the one which boils off.
4. Add about half a litre of strong concentrated solution of common salt and then allow cooling.
5. Remove the hard crust at the surface of the liquid and, using wires, process them into bars.

Discussion

1. What is the use of the common salt?
2. Identify the ingredients you can add to the soap during preparation to make it suitable as a toilet soap
3. What materials can you add to the soap to make suitable as a good washing agent?
4. Design a flow chart detailing the steps used in the preparation of the soap.

Soapless detergents

Have you used liguid liquid soap, omo or nomi in your home? The liquid detergents such as soap, nomi and omo are examples of soapless detergents.

Figure1.32: Different soapless detergents1

Soapless detergents are substances that are used to improve the cleaning properties of water by facilitating the emulsification and removal of grease

Soapless detergents function in the same way as soapy detergents because they have a similar structure but soapless detergents are more soluble than soapy detergents and therefore clean more effectively. Even when hard water is used, soapless detergents do not form scum but soap does. In the laboratory, soapless detergents can be prepared by boiling a vegetable oil such as castor oil with concentrated sulphuric acid. In the next activity, you are going to prepare a sample of detergent in the laboratory.

Activity 1.30 Preparing soapless detergent

What you need

• Concentrated sulphuric acid
• Boiling tube
• Dropper
• Castor oil
• Cold water
• Test tube
• Spatula

Caution: be careful when using concentrated sulphuric acid, it is corrosive to the skin and can cause burns.

What to do:

1. Add 8cm³ of concentrated sulphuric acid to a boiling tube.
2. Using the dropping pipette, add 4cm³ of castor oil very carefully to the boiling tube.
3. swirl gently to mix. Does the test tube become hot?
4. Add 20cm³ of cold water in a boiling tube.
5. Carefully pour the reaction mixture from the first tube into water.
6. Stir to remove the excess pf acid into the water and then decant the water off, leaving a pinkish-grey sludge.
7. Wash the product again with two more portions of water.
8. Use a spatula to transfer a small quantity of the to clean test tube.
9. Add a 5cm³ of water, and shake well. What happened?

Discussion

1. What locally available materials can you use to prepare detergents?
2. Why do think detergents are very popular washing materials?
3. Design a poster showing the different steps followed in making the detergents that you use to encourage people in your area to make them at home

Detergents wash better than soap

Do you know why detergents are more popular than soap for washing and cleaning purposes? It is because detergents do not form scum (figure 1.33).

Figure 1.33: washing with a detergent 1

No detergent is wasted by reacting with the hard water because of formation of soluble salts with calcium and magnesium compounds in water. So, you use soap for cleaning. In the next activity you will demonstrate this property of detergents.

Activity 1.31 To show that soapless detergents do not form with hard water

What you need

Test tubes with fitting bungs

Hard water (from lake, spring or well)

Soap solution

Sapless detergent

What to do

1. Add a few drops of soap solution to half a test tube of water.
2. Fix a bung at the top and shake well. What do you observe?
3. Now the experiment using a soapless detergents. What do you observe?

Discussion

1. Explain the difference in the two observations.
2. In your groups, search the internet or in text books and identify more advantages and dis advantages of using soapless detergents over use of soap.
3. Organize your findings in (b) in a suitable table and present them to the rest of the class.

ACTIVITY OF INTEGRATION

Imagine you are a minister of energy environmental resources. You have been invited as a guest of honor on the world carbon resources day.

Figure 1.34: Carbon based resources 1

At the venue, you are going to find the different technical staff in your line ministry and other district level dignitaries. The day is meant to enlighten the people about the carbon- based materials, how they can be harnessed and their importance in everyday life. Prepare the speech that will be delivered at the function.

The speech should include:

• Carbon-based materials
• Their importance

CHAPTER SUMMARY

• Many of the materials in our surroundings contain carbon.
• Compounds of carbon are called organic compounds.
• Some carbon compounds are made by man and called synthetic compounds.
• Organic compounds that exist in living materials and their products are classified as natural organic compounds.
• Petroleum and natural gas were formed from plants and animal materials over a long period of time.
• The main component of petroleum and natural gas is hydrocarbons. Hydrocarbons are compounds containing carbon and hydrogen only.
• Different fractions in crude oil can be separated by fractional distillation.
• The different fractions of petroleum have different properties and a range of uses.
• Natural is mainly made up of methane but contains small quantities of other alkanes and other elements.
• Biogas is obtained by decomposing organic matter in limited supply of air.
• Polymers are giant molecules obtained by the chemical combination of many small molecules.
• Plastics are synthetic materials obtained from crude oil. They are polymers of simple molecules. 
• Carbon compounds can be grouped into homologous series. Homologous series are compounds with the same functional group.
• Alkanes, alkenes and alkynes are three groups of compounds containing carbon and hydrogen.
• Alcohols contain the hydroxyl group and have special properties.
• Ethanol is a key alcohol and has many uses including use as an alcoholic drink.
• Alcohol must be used with caution as it may harm the body.
• Organic acids are components of many plants and animals. They can be used as preservatives in many foods and drinks. They are particularly used in the making of soap.
• Soap is a sodium salt of an organic acid formed when fats are heated with a strong alkali.
• Soapless detergents are better washing agents than soap. They however have their challenges so should be used carefully.

REVISION QUESTIONS

1. (a)Explain the following terms:

1. Homologous series
2. Functional group

(b) Name two other compounds which are in the same homologous series as methane

2.  The source of organic materials is petroleum and natural gas.

                (a) Describe how the component fractions in petroleum are separated from each other.

(b) Give one use of each of the fractions

3. (a) Describe you would distinguish experimentally between an alcohol and a carboxylic                        acid.

      4. Briefly explain the harmful effects of drinking ethanol?

5. (a) Distinguish between natural and artificial polymers.

    (b) Give two examples in each case of natural and ratified polymers.

6. (a) what is soap?

    (b) describe how soap can be prepared at home

    (c) discuss the advantages of using soapless detergents over soap.