C7 further chemistry
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C7: Further Chemistry. C7.2 Alcohols, carboxylic acids and esters. Organic Chemistry. Organic chemistry  is a sub-discipline in chemistry that involves the scientific study of the structure, properties and reactions of organic materials and compounds. Meeting the Alkanes.

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C7: Further Chemistry

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C7 further chemistry

C7: Further Chemistry


C7 2 alcohols carboxylic acids and esters

C7.2 Alcohols, carboxylic acids and esters


Organic chemistry

Organic Chemistry

Organic chemistry is a sub-discipline in chemistry that involves the scientific study of the structure, properties and reactions of organic materials and compounds.


Meeting the alkanes

Meeting the Alkanes

The alkanes are hydrocarbons, containing only hydrogen and carbon


The alkanes

The Alkanes

Methane CH4

Propane C3H8

Ethane C2H6

Butane C4H10


C7 further chemistry

Why do we use alkanes?


Burning alkanes

Burning alkanes

If there is plenty of air, ie enough oxygen:

Methane + Oxygen  Carbon dioxide + Water

Can you write the balanced symbol equation?

CH4 + 2O2  CO2 + 2H20

(g)

(g)

(g)

(g)

Did you remember state symbols?


Alkanes and aqueous reagents

Alkanes and Aqueous Reagents

H

H

H

C

C

C

H

H

Alkanes are unreactive towards aqueous reagents because they contain only C—C and C—H bonds, which are difficult to break and therefore unreactive

H

H

H


Functional groups

Functional Groups

All of the characteristic properties of alcohols are due to the presence of this functional group.

H

H

C

C

H

O

H

H

H

Can you give the molecular formula, structural formula, stick diagram for methanol and ethanol?

H

H

Ethanol

Ethane


C7 further chemistry

Why do we need methanol and ethanol?


Uses of alcohols

Uses of alcohols

C2H5OH

CH3OH


Burning alcohols in air

Burning Alcohols in Air

Can you write out the word equation for the combustion of ethanol in air.

Write out the balanced symbol equation

Don’t forget state symbols

Ethanol + Oxygen  Water + Carbon dioxide

C2H5OH + 3O2 3H20 + 2CO2

(l)

(g)

(g)

(g)

Alcohols burn in air to produce carbon dioxide and water because of the presence of a hydrocarbon chain


C7 further chemistry

Why have I been using methanol and ethanol for the demonstrations?


Physical properties

Physical Properties

H

H

C

O H

Methanol

H

H

H

H

H

H

H

H

H

C

C

H

C

C

C

C

C

C

The longer the hydrocarbon the stronger the intermolecular forces and therefore the higher the boiling point.

Longer hydrocarbons are also less soluble in water as they behave more like an alkane and so float on top of water due to their low density

O H

Octanol

H

H

H

H

H

H

H

H


Reactions with sodium

Reactions with Sodium

Remember this?

Sodium with water

Alcohols- Sodium sinks in alcohol and doesn’t melt, it will steadily give off hydrogen

Alkanes- Do not react with Sodium

Sodium with alcohol


Quick quiz so far

Quick Quiz so far

  • Draw the structural formula for butanol

  • Write the molecular formula for butanol

  • Draw the structural formula for hexane

  • Write the molecular formula for hexane

  • Write the molecular formula for an alkane with 25 carbon atoms.

  • How many bonds does oxygen make in methanol?

    7. Give an example of a use for ethanol

    8. Give an example of a use for methanol


C7 further chemistry

Butanol

C4H10O

Hexane

C6H14

C25H52

2

Fuel/feedstock for synthesis/solvent/used in perfume

Solvent, antifreeze, feedstock for adhesives and plastics


How do we make ethanol

How do we make ethanol?

  • What process do we use? It will be used in home brewing

  • Fermentation is a key process for obtaining ethanol. It is relatively cheap and requires wheat or beet sugar.

  • The process involves the anaerobic respiration of yeast at temperatures between 20 and 40°C and at pH 7.


C7 further chemistry

Why is there a limit on the strength of alcohol that can be made?


Making alcohol

Key

Sugar

Ethanol

Making Alcohol

X

When the ethanol concentration gets too high it kills off the yeast cells


C7 further chemistry

So how do we make stronger alcohol?


How do we obtain a concentrated solution

How do we obtain a concentrated solution?

  • Ethanol has a different boiling point to water. We can therefore separate water and ethanol using distillation.


Give it a thought

Give it a thought

Can you balance this equation?

C6H12O6 → CH3CH2OH+ CO2

C6H12O6 → 2 CH3CH2OH+ 2 CO2

Can you name the chemicals?


Other ways to make ethanol

Other ways to make ethanol

Genetically modified E. coli bacteria can be used to convert waste biomass from a range of sources into ethanol

Optimum conditions:

Temperature remain between 25-37oC

Optimum pH level needs to remain constant


Other ways to make ethanol1

Other ways to make ethanol

They introduce new genes into the E.colibacteria allowing it to digest all the sugars in the biomass and covert them into ethanol. Therefore we can use a wide range of biomass to make ethanol rather than staying as waste eg corn stalks.

Feedstock


Linking alkanes and alcohol

Linking alkanes and alcohol

It is also possible to convert ethane into ethanol

Crude Oil undergoes fractional distillation

Long chain hydrocarbons (alkanes) are vaporised then cracked using a catalyst and heat

Any unreacted products can be recycled and fed through the system again

The molecules are purified using fractional distillation producing ethene

Ethene is then reacted with steam, at a high temperature and with a catalyst to produce ethanol


Write out the symbol equation

Write out the Symbol Equation

Ethene + Steam  Ethanol

C2H4 + H20  C2H5OH

(g)

(g)

(g)


The uk is the world s largest producer of synthetic ethanol

The UK is the world's largest producer of synthetic ethanol

Why is this not a good fact?


C7 further chemistry

  • Make a table listing the advantages and disadvantages of each method of producing ethanol.


Tackling the 6 marker

Tackling the 6 marker

Which method do you think has the largest impact on the environment? Give reasons for your answer.


The alkanes1

The Alkanes

H

H

H

H

H

C

H

C

C

C

H

H

H

H

H

H

H

H

H

H

H

H

C

C

C

C

C

H

H

H

C

H

H

H

H

H

H

H


C7 further chemistry

H

H

C

O H

  • Make models with molymods

H

H

H

H

H

H

H

H

H

H

H

C

C

H

O H

C

C

H

C

C

C

C

C

C

O H

H

H

H

H

H

H

H

H

H

H


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