Advantages and disadvantages of methods of preparing alcohol

Industrial


Advantages -
It will be continuous
Reactions are reversible
Produces 100% yield
Fast reaction rate

Disadvantages -
Non Renewable
Requires a lot of energy
Requires high pressure and temperature

Fermentation

Advantages -
Gentle Temperature
Uses renewable sources (sugar cane)

Disadvantages -
A batch process - inefficient
Slow rate - Several days for each batch
Produces impure ethanol - needs further processing

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 = 1,2-dibromoethane

2.       Draw the displayed formula of the reaction above

3.       Explain the observations
          Turns brown to colourless liquid
        

        


4.       Why does this reaction not need a catalyst?
          Because the C=C is reactive

5.       What type of reaction is this called?
          Addition Reaction

6.       Explain why this reaction is useful
          It's a chemical test that distinguish saturated and unsaturated hydrocarbons
          (alkanes and alkenes)

3.6 and 3.7 I can recall the general formula and displayed formulae of alkenes

4. What is the general formula for alkenes?

CnH2n

5. Describe and explain the trend in boiling point

Boiling point goes up as the chain gets longer because more intermolecular force is needed to break. 

6. Explain why there is no such compound as methene

Because Methane only has one carbon so it can't form a double bond.

7. How do you quickly identify from the displayed formula that the hydrocarbon is unsaturated?

Because there is double bond in the carbon so it is unsaturated.

3.5 I can recall the reaction of methane and bromine

1. Alkanes react with bromine in the presence of ultra violet light.

2. Explain why this condition is necessary.

The UV is the essential energy required in order for the chemical reaction to happen.  

3. What is this type of reaction called = Substitution Reaction.

4. State and explain the observations = Brown gas turns colourless because the bromine as a reactant is brown and the products bromomethane and hydrogen bromide is 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 (g) + Cl2 (g) --> C2H5CL (g) + HCl (g)

7. State and explain the observations in this chemical reaction

Yellow Gas turns Colourless because the chlorine as a reactant is yellow and the products chloroethane
 and hydrogen chloride is 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 combustion

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 dangerous to the human body (see objective 5.11)

7. Where can you find incomplete combustion? Cars

8. What is used to reduce the harmful products from incomplete combustion? Catalytic Converter

9. During incomplete combustion a smoky flame is often seen, explain this observation

    Grey Clouds of Gases & Nasty Smell

Extn: write a balanced equation (with state symbols) for the combustion of propane gas

C3H8 + 5O2 --> 3CO2 + 4H2O

3.2 and 3.3 I can recall the the general formula and displayed formulae of alkanes

What is the General Formula for Alkanes:
C _nH_2n+2
Describe and explain the trend in boiling point:
The boiling point goes higher when there are more atoms in the molecule

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	Members of the same series, or family having similar chemical properties.	alkanes
Hydrocarbon	A hydrocarbon is a compound containing only hydrogen and carbon.	crude oil, methane, ethane, propane, butane, pentane
Saturated hydrocarbon	Molecules with a single bond throughout the whole structure	Any Alkanes (Methane)
Unsaturated hydrocarbon	Molecule with a double/triple bond	Any Alkenes (Ethene)
General formula	A mathematical formula to express the number of carbon and hydrogen atoms in a molecule	C nH2n+2
Isomerism	Molecules having the same formula, but are structured differently.	2,2 Dimethylpropane

5.13 I can describe catalytic cracking of long-chain hydrocarbons

Define the term catalyst

Catalyst - A substance that changes the rate of chemical reaction.

Why is a catalyst used?

Catalyst is used to speed up reaction so more products could be made in a shorter range of time.

Why are high temperatures needed?

The high temperatures are needed to provide the energy to break the strong covalent bonds in the molecule.
High temperatures also vary the rate of reaction because the particles move faster, they will have more chance of collision therefore increase the rate of reaction.

What is the process called to convert long chain hydrocarbons to short chain hydrocarbons

Cracking

How are the bigger molecules broken down

By Heating

Crackling is an example of what decomposition reaction

Thermal decomposition reaction

Why are catalyst needed in cracking

To speed up reaction

Why do we need to crack hydrocarbons

To produce more useful stuff such as Refinery Gas or Petrol

What gas is produced from cracking Paraffin

Ethene

 What is the catalyst for cracking paraffin

Aluminium Oxide

5.12 I can recall the problems associated with the fractional distillation of crude oil

a) When crude oil undergoes fractional distillation there are too many long chain hydrocarbons (eg Bitumen) produced and not enough short chain hydrocarbons (eg Refinery Gas)


b) To solve these problems the long chain hydrocarbons undergo a chemical reaction called Cracking

5.11 I can recall how nitrogen oxides are formed in car engines

a.       Write the general equation for the combustion of a fuel

Fuel + Oxygen ---> Oxides + Energy 

b.      During combustion the nitrogen in air can react to form what gases?

NOx Gases (NO or NO2)

c.       What condition is necessary for the formation of these gases?

Very High Temperature / Energy

d.      In what common object is this condition found?

Car Engines

e.      Why is this condition needed for nitrogen to react?

Because Nitrogen Exists as Diatomic Molecules and it has three strong covalent bonds which makes it

hard for the bonds to break

f.        What are the dangers of the products from this reaction?

It could cause asthma and it could also shorten people's life by 9 years. Also it could erode plants and

animals due to the formation of Acid Rain which is dangerous

5.10 I can recall the problems associated with incomplete combustion

What are the properties of carbon monoxide
 It is colourless, odourless, tasteless and invincible to all human senses

Explain how carbon monoxide is formed
It is formed by having insufficient amount of oxygen in combustion process


Fuel + INSUFFICIENT OXYGEN -------> CO             +  H20       +   Energy
                                                   Carbon monoxide    Water

Explain why carbon monoxide is poisonous
Carbon Monoxide sticks to the haemoglobin faster than the oxygen causing not enough oxygen is carried
in the red blood cells causing poisoning that eventually can cause death due to insufficient amount of
oxygen.

5.9 I can describe the trend in boiling point and viscosity of the main fractions

a.       What is the trend in boiling point of the fractions?

 The boiling point goes higher as the fractionating column goes down

b.      Define viscosity (source your definition)

 resistance of a liquid to sheer forces (and hence to flow)

/ ability for liquid to flow

source: http://definr.com/

c.       What is the trend in viscosity of the fractions?

The viscosity gets higher as the fractionating column goes down

d.      What is the trend in colour of the fractions?

The colour gets darker as the fractionating column goes down

e.      Why is crude oil separated into fractions?

Because crude oil by itself is useless because it's a mixture so needs to be separated to fractions to be 

more useful

f.        What process is used to separate crude oil into fractions?

Fractional Distillation

g.       What physical property allows this process to work?

Difference in boiling points

5.8 I can recall the names and uses of the main fractions obtained from crude oil

 

5.6 I can recall what crude oil is made from

a. Define the word hydrocarbon….	Hydrocarbon is a compound containing Hydrogen and Carbon
b. What is crude oil made from?	They are made of hydrocarbons which originally came from dead animals and plants
c. Define the word compound….	A molecule containing two or more elements
d. Define the word mixture…..	Mixture is two or more elements mixed together but not chemically bonded

d. How long does crude oil take to make?	150 million years
e. Where does the energy in crude oil originally come from?	Sun
f. How is crude oil different from coal?	Crude oil came from dead plants and animals that lived beneath the sea long time ago but coal is just from dead tress which was buried underneath the surface
g. Crude oil, coal and natural gas are collectively known as _________ fuels	Fossil
h. How is crude oil transported when it is extracted from the ground?	By pipeline or an oil tanker. Pipelines are only used when the oil found is close to the refinery. Oil tanker will transport oil to the rest

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