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

What is the general formula for the alkanes?

C_nH_2n+2

Describe and explain the trend in boiling points.
_{As the number of atoms increases, from methane to pentane, the boiling point increases as well because the number of atoms and bonds in the molecules increaes. This means that more energy, heat, is required to turn the hydrocarbon into a gas. This is beuse there are more intermolecular forces which exists between the molecules. ay}          

3.4 I can recall the products of complete and incomplete combustion of alkenes

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 produced this gas is a toxic gas to the human body (see objective 5.11)

7.       Where can you find incomplete combustion?

            In car engines

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

            A catalytic converter

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

            The smoky flame is produced by unburnt, solid, carbon molecules floating in the air - soot.

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

     

C₃H_{8 (g)} + 5O_{2 (g)}  →  3CO_{2 (g)} + 4H₂O _(L)

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

Term	Definition	Example
Homologous series	A family of hydrocarbons with the same general formula.
Hydrocarbon	A molecule consisting only of hydrogen and carbon atoms.	Methane
Saturated hydrocarbon	A hydrocarbon with only single covalent bonds which can not hold any more atoms with out additional bonds being formed.	Pentane
Unsaturated hydrocarbon	A hydrocarbon containing double or triple covalent bonds that can hold additional atoms without creating any more bonds, but only by moving bonds.	Butene
General formula	A mathmatical formula that applies to an entire homologous series and will allow one to find the number of hydrogen atoms in a certain hydrocarbon based on the number of carbon atoms in the molecule.
Isomerism	The trait of molecules to become isomers. An isomer is a hydrocarbon with the same molecular formula as it's corresponding hydrocarbon, but with a different atomic arrangement.	2,2 dimethylpropane

5.13 - I describe the catalytic cracking of long-chain hydrocarbons.

1. A Catalyst is a substance that changes the rate of a reaction without being used up itself.

2. A Catalyst (silica or alumina in this case) is used in the process of catalytic cracking to increase the rate of reaction. This increases the amount of short- chain molecules that one can produce in a shorter amount of time. In turn, this increases the profits of the oil company and produces more useful hydrocarbons more quickly.

3. A high temperature (600 - 700 degrees Celsius) is used during the process of catalytic cracking. This high temperature is necessary because it increases the rate of reaction further and provides additional energy that is used to break the bonds of the long-chain hydrocarbons more effectively. This increases the output of short-chain hydrocarbons and increases the profits of the oil company.

5.12 - I recall that fractional distillation of crude oil produces more long-chain hydrocarbons than can be used directly and fewer short-chain hydrocarbons than required

a.       When crude oil undergoes Fractional Distillation there are too many large chain hydrocarbons (eg Fuel oil and Bitumen) produced and not enough small chain hydrocarbons (eg Gasoline and Refinery Gases).

b.      To solve these problems the large 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 nitrogen may react with oxygen to form Nitrogen Oxides or NOx gases.
c.       What condition is necessary for the formation of these gases?	In order for the Nitrogen and Oxygen in the air to react during combustion, an extremely high temperature is necessary.
d.      In what common object is this condition found?	The high temperature necessary to form NOx gases can be found in the combustion engine of an automobile or car.
e.      Why is this condition needed for nitrogen to react?	A high temperature is necessary because it provides the energy needed to break to strong, triple covalent bond between the Nitrogen atoms. Ultimately, the high temperature allows the reaction to take place by causing the Nitrogen to become reactive instead of inert.
f.        What are the dangers of the products from this reaction?	The NOx gases have several dangerous properties. When dissociated in water, they form Nitric acid, which contributes to acid rain. In addition, the NOx gases can cause Asthma, nausea, may agitate tissues, and overall can remove up to nine years from one’s lifespan.

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