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

1) when crude oil undergoes fractional distillation, there are to many long chain hydrocarbons (e.g. bitumen) produced and not enough short chain molecules (e.g. kerosine)

2) To solve these problems the long chain molecules undergo a chemical reaction called cracking

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

1)Write the general equation for the combustion of a fuel
fuel + oxygen --> carbon dioxide + water + energy

2)During combustion the nitrogen in air can react to form what gases?
The nitrogen combust to from NOX gases

3) What condition is necessary for the formation of these gases?
Extremely high temperatures are needed for the formation of these gases

4)  In what common object is this condition found?
a car engine

5) Why is this condition needed for nitrogen to react?
Nitrogen molecules are bonded together with a triple covalent bond and are therefore inert. High temperatures are needed to break this strong bond

6)  What are the dangers of the products from this reaction?
You may be subjected to asthma and other diseases. It can also produce acid rain which is corrosive.

5.10 I can recall the problems associated with incomplete combustion

1)What are the properties of carbon monoxide?

It is a colourless, odorless, poisonous gas that has a strong affinity towards haemoglobin.

2)Carbon monoxide is formed when a hydrocarbon is burned in an insufficient supply of oxygen.
3)Carbon monoxide is poisonous because it will bond with the haemoglobin in your blood and stop your blood from carrying oxygen around your body.

5.6 I can recall what crude oil is made from

a. Define the word hydrocarbon….	a compound containing only hydrogen and carbon
b. What is crude oil made from?	formed from tiny animals and plants that lived in the sea
c.       Define the word compound….	two or more elements chemically combined
d.      Define the word mixture…..	two or more substances physically combined

 NOTE:Answers in white font

. How long does crude oil take to make?	150 million years
e. Where does the energy in crude oil originally come from?	sun light
f. How is crude oil different from coal?	crude oil is liquid while coal is solid and is not a hydrocarbon
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 by oil tanker

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

1)What is the trend in boiling point of the fractions?

The volatile substances with lower boiling points rise to the top of column and the substances with higher boiling points are collected at the bottom. The boiling points are in ascending order from top to bottom in the column. In the test tube diagram above, the boiling point of the substances decreases from left to right.  In general, the larger the molecule, the higher its boiling point.

2)Define viscosity.

Viscosity is a measure of the resistance of a fluid which is being deformed by shear or tensile stress.
Source: www.wikipedia.com 

3)  What is the trend in viscosity of the fractions?

In general, the larger the molecule, the higher the viscosity. As you know, large molecules have higher boiling points because there are more bonds to break. Therefore, the viscosity decreases as you go up the column. In the diagram above, the viscosity of the fractions decrease from left to right.

4)What is the trend in colour of the fractions?

The colour of the fractions become darker as you go up the column. In the diagram above, the colour gets darker from right to left. In general, the larger, more viscous the molecule,  the darker its colour.

5)Why is crude oil separated into fractions?

Crude oil itself is a useless substance and therefore it is separated through fractional distillation to form other useful substances.  

6)What process is used to separate crude oil into fractions?

Crude oil is separated by a process called fractional distillation in which the different boiling points of the unique substances allow it to be separated into fractions. The substances with the lowest boiling point at the top and the substance with the highest boiling point at the bottom.  

7) What physical property allows this process to work?

It has different boiling points.

 

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

click on the image to see the answers

5.7 I can describe how crude oil is separated