Advantages | Disadvantages | |
Fermentation | · Renewable recourses (sugarcane · Little energy needed (gentler temperatures) · Doesn’t produce harmful gasses | · Production is slow · Product is impure · Its expensive · Many people are needed to produce it (Batch process - inefficient) |
Industrially | · Product is pure · Not that many workers are needed as they have machinery · Production is very fast | · Lots of energy is needed · High temp. and pressure conditions are needed · Non renewable (oil) |
Thursday, September 1, 2011
Advantages and Disadvantages of 2 Methods of Creating Alcohol
Tuesday, June 21, 2011
3.8 I can describe the reaction between alkenes and bromine
1. Write the word equation showing the reaction between ethene and bromine water
Ethene + Bromine (l) --> bromoethane + hydrogenbromide
or dibromoethane
2. Draw the displayed formula of the reaction above
3. Explain the observations
The liquid turns from brown/ yellow to colourless because the bromine molecules are separated and loses it's colour
4. Why does this reaction not need a catalyst?
A catalyst is not needed because alkenes and the carbon carbon double bond is very reactive.
5. What type of reaction is this called?
This is called an addition reaction
6. Explain why this reaction is useful
Because it shows when a non saturated bond is present
Tuesday, June 7, 2011
3.2 and 3.3 I can recall the general formula and displayed formula of alkanes
What is the General formula of Alkanes? CnH2n+2
Describe the Trend in Boiling Points: : A straight-chain alkane will have a boiling point higher than a branched-chain alkane due to the greater surface area in contact with the heat source, also, as the mass of the alkane increase the boiling point increases
Draw the displayed formula of the three isomers of pentane:
3.1 I can explain the terms homologous series, hydrocarbon, saturated, unsaturated, general formula and isomerism
Term | Definition | Example |
Homologous series | A family or series of Hydrocarbons that have similar chemical properties. | Alkanes Alkenes |
Hydrocarbon | Organic compounds that consist of only Hydrogen and Carbon | Ethanol |
Saturated hydrocarbon | Alkanes (paraffins) - hydrocarbons that have a carbon 'skeleton' or 'back-bone' Hydrogen must have 4 bonds | Methane |
Unsaturated hydrocarbon | Alkenes (olefins) - Hydrocarbons with at least one carbon to carbon double bond. | Ethylene |
General formula | Within a series; it shows the relationship between the number of C atoms and H atoms in the compounds Alkenes - CnH2n. | Hexane C6H14 Propene C3H6 |
Isomerism | Isomers have the same formula but their atoms are arranged differently. Different physical properties | Propane |
Friday, May 27, 2011
3.5 I can recall the reaction of methane and bromine
Alkanes react with bromine in the presence of UV Light
· Explain why this condition is necessary UV light is the source on energy in order to break the weak inter molecular forces in between molecules.
3. What is this type of reaction called A substitution reaction
4. State and explain the observations - Alkanes are colourless and bromine is brown, when the reactants are given energy to break intermolecular bonds the bromine is less saturated and the product is therefore colourless
5. Draw the displayed formula of the reaction between methane and bromine (upload a photo)
6. Write out a balanced (with state symbols) the reaction between ethane and chlorine
C2H6 + Cl2 à C2H5 + HCl
7. State and explain the observations in this chemical reaction
The chorine begins as a green/yellow gas, when it reacts the chlorine is less saturated and the product is more saturated making the product colourless
3.4 I can recall the products of complete and incomplete combustion of alkenes
1. Saturated hydrocarbons are called alkanes
2. Small chain hydrocarbons are used as fuels
3. The reaction is called a substitute reaction
4. The word equation for this chemical reaction is :
fuel (hydrocarbon) + oxygen → Carbon Dioxide + Water + ENERGY (heat, light, sound)
5. If there is insufficient oxygen then the word equation is:
fuel (Hydrocarbon) + Oxygen → Carbon Monoxide + Water + ENERGY (heat, light, sound)
6. The problem with this reaction is that Carbon Monoxide is produced this gas is a poison to the human body (see objective 5.11)
7. Where can you find incomplete combustion? Car engines
8. What is used to reduce the harmful products from incomplete combustion? Catalytic Converters
9. During incomplete combustion a smoky flame is often seen, explain this observation
During incomplete combustion a smoke is seen, this is solid carbon that has not reacted during the combustion reaction
Write a balanced equation (with state symbols) for the combustion of propane gas
C3H8 + 5O2 --> 3CO2+4H2O
10. Describe the two chemical tests for Water:
Copper 2 sulphate powder: white- blue
colbalt2 chloride litmus paper : blue- pink
Tuesday, May 17, 2011
5.13 I can describe catalytic cracking of long-chain hydrocarbons
Read "Chemistry For You" Page 145
Catalyst - A catalyst is a substance that has the ability to change the rate of reaction
Why are catalysts used? - Catalysts are usually used in order to speed up reaction rates, they can also slow them down, for instance to postpone rusting.
Why are high temperatures needed? - High temperatures are needed for the amount of energy the molecules need to react, it also speeds up the rate of reaction.
What equipment is used during the process?
A boiling tube with a delivery tube with a test tube or reservoir and a basin of water.
What catalysts are used to convert long chain alkanes to alkenes and shorter chain molecules? - Silica or alumina. Video > A ceramic catalyst can be used (silicon)
How is the Gas collected?
Over water
What safety aspects are preformed during the experiment?
The gas will be collected over water, do not allowed suck-back of water ( it will turn into steam and cause and explosion)
What causes the cracking to occur?
Video > first you must heat the ceramic pot (catalyst) and then move the flame which will encourage the liquid paraffin to turn into a vapour and meet the catalyst, this causes the cracking to occur.
What is Cracking?
When the Long Chain gas molecules produce smaller chain gas molecules which will then be collected. (In the Video > triggered by ceramic catalyst)
Catalyst - A catalyst is a substance that has the ability to change the rate of reaction
Why are catalysts used? - Catalysts are usually used in order to speed up reaction rates, they can also slow them down, for instance to postpone rusting.
Why are high temperatures needed? - High temperatures are needed for the amount of energy the molecules need to react, it also speeds up the rate of reaction.
What equipment is used during the process?
A boiling tube with a delivery tube with a test tube or reservoir and a basin of water.
What catalysts are used to convert long chain alkanes to alkenes and shorter chain molecules? - Silica or alumina. Video > A ceramic catalyst can be used (silicon)
How is the Gas collected?
Over water
What safety aspects are preformed during the experiment?
The gas will be collected over water, do not allowed suck-back of water ( it will turn into steam and cause and explosion)
What causes the cracking to occur?
Video > first you must heat the ceramic pot (catalyst) and then move the flame which will encourage the liquid paraffin to turn into a vapour and meet the catalyst, this causes the cracking to occur.
What is Cracking?
When the Long Chain gas molecules produce smaller chain gas molecules which will then be collected. (In the Video > triggered by ceramic catalyst)
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