3.4 recall the products of complete and incomplete combustion of alkenes

Read Chem 4 You pg 147 and Collins pg 157

1.       Saturated hydrocarbons are called alkanes

2.       Small chain alkanes are used as fuels

3.       The reaction is called combustion

4.       The word equation for  this chemical reaction is :

fuel (Alkane) + Oxygen→ Carbon Dioxide + Water+ ENERGY (heat, light, sound)

5.       If there is insufficient oxygen then the word equation is:

fuel (Alkane) + Oxygen→ Carbon Monoxide+ Water+ ENERGY (heat, light, sound)

6.       The problem with this reaction is that Carbon Monoxide is produced this gas is toxic to the human body (see objective 5.11)

7.       Where can you find incomplete combustion?

Incomplete combustion occurs in areas with little oxygen, burning a fire in the house or in  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

A smoky flame is seen this is a result to incomplete combustion the black smoke is called soot and is solid Carbon.

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

C₃H_{8 (g)} + 5O_{2 (g)}  à 3CO_2(g) + 4H₂O_(g)

3.2 and 3.3 I can recall the general formula and displayed of Alkanes

What is the general formula for alkanes?

C_nH_2n

Describe and explain the trend in boiling point

 As the chains of the hydrocarbon get longer, the boiling point increases. 

Formula of the Three Isomers

3.1 I can explain the terms homologous series, hydrocarbon, saturated, unsaturated, general formula and isomerism

Term	Definition	Example
Homologous series	A group of hydrocarbons with the same type of formula	Alkane
Hydrocarbon	A compound that is made out of carbons and hydrogens	Crude Oil
Saturated hydrocarbon	A saturated hydrocarbons only contains single bonds	Methane  part of the Alkanes
Unsaturated hydrocarbon	An unsaturated Hydrocarbon contains single and double( covalent ) bonds.	Ethene part of the Alkene
General formula	A mathematical formula showing the ratio of atoms.	For Alkenes C(n) H(n+2)
Isomerism	An Isomer is a molecule with the same molecular formula with a different atomic arragenment which results into different physical properties.	2,2 Dimeythelprotane

5.13 I can describe catalytic cracking of long-chain hydrocarbons

Catalyst: a catalyst helps to speed up a reaction.


Why is a Catalyst used?


A catalyst is used to speed up a reaction, this is useful because with the catalyst you would be making the product faster, therefore sell it faster and get more money. 


Why are high temperatures needed?


High temperatures (between 600 - 700) degrees are needed to 'crack' the strong bonds of hydrocarbons into smaller chained hydrocarbons.







8 Questions about this video - Cracking Paraffin.


What does liquid Paraffin contain?
Liquid Parafin contains long chained hydrocarbons


What Happens when Liquid Paraffin gets Heated up?
The Liquid Paraffin made out of long chained hydrocarbons 'crack' into smaller chained hydrocarbons.


What is a catalyst and which one is used in the video?
A catalyst speeds up the process of a reaction and the catalyst used in the video is a ceramic catalyst ( a broken pot) which contains silica that is used to speed up the process. 


What important safety precautions are carried out in the experiment?
The gas will be collected under water, you should take out the delivery tube out of water to prevent suck back which can cause an explosion.


Why are the first bubbles that come out are not collected?
The First couple of bubbles that are made is due to the air expanding from the heat thus moving the air out.


 What is used to soak the liquid paraffin ?
Ceramic Wool


What is the process to distill crude oil called ?
Cracking


Why does Liquid Paraffin heated up?
To break the long chain bonds into smaller ones by heat.

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 large chained hydrocarbons (eg. Bitumen) produced and not enough small chain hydrocarbons (eg. Petrol).

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 ---> Carbon Dioxide + Water + Energy 

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

During combustion the nitrogen combines in the air to form NOx's

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

For these gases to form there needs to be high temperatures to break the triple bonds.

d.      In what common object is this condition found?

In Cars.

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

There needs to be high temperature to break the diatomic nitrogen molecules because they all have triple covalent bonds, and the heat breaks them up

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

The dangers of this product is that it forms NOx's which cause cancer, asthma, lung problems and shortens people life.

5.7 I can describe how the industrial process of fractional distillation separates crude oil into fractions