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

C₃H_{8 +} 5O₂ --> 3CO₂+4H₂O

10. Describe the two chemical tests for Water: 
Copper 2 sulphate powder: white- blue 
colbalt2 chloride litmus paper : blue- pink

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)

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

Read Chemistry For You Page 145

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 gases)

b. To solve these problems the long chain hydrocarbons undergo a chemical reaction called crackin (see objective 5.13)

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 ----> Energy + Oxides

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

       NOx Gases

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

        High Temperatures and presence of Oxygen

d.      In what common object is this condition found?

        Cars

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

       Because Nitrogen molecules are diatomic and have strong triple covent bonds

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

        Asthma, Acid rain and Cancers. 

5.7 I can describe how crude oil is separated

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

3 minutes 4 Seconds

a.       What is the trend in boiling point of the fractions? - As you go up the fractionating column the boiling point decreases 

b.      Define viscosity (source your definition)  - Resistance of a liquid to shear forces (and hence to flow) or the thickness of a liquid 

c.       What is the trend in viscosity of the fractions? - The higher the boiling point the greater the viscosity 

d.      What is the trend in colour of the fractions? - The higher the boiling point the darker the colour

e.      Why is crude oil separated into fractions? - Because each fraction has a different use whilst Crude oil unseparated is virtually useless

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

g.       What physical property allows this process to work? -  Boiling point

Image taken from Chem 4 You pg 144

5.10 I can recall the problems associated with incomplete combustion

1.       What are the properties of carbon monoxide

 - Carbon Monoxide is an odourless tasteless gas that is very poisonous. 

2.       Explain how carbon monoxide is formed

- Carbon Monoxide is formed when there is the event of incomplete combustion - this occurs due to insufficient amounts of oxygen during a combustion reaction.

3.       Explain why carbon monoxide is poisonous

- Haemoglobin's attraction to Carbon monoxide is much greater than it's attraction to oxygen, the gas is not used in respiration and therefore remains circulating in the respiratory system, all of the haemoglobin is already bonded to the Carbon Monoxide and eventually starves all organs of Oxygen. 

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

Answers: http://sashaschemistryblog.blogspot.com/2010/05/58-answers.html