Lesson Notes By Weeks and Term - Senior Secondary 1
Petroleum II
Petroleum II
Term: 3rd Term
Week: 10
Class: Senior Secondary School 1
Age: 15 years
Duration: 40 minutes of 5 periods each
Date:
Subject: Chemistry
Topic:- Petroleum II
SPECIFIC OBJECTIVES: At the end of the lesson, pupils should be able to
INSTRUCTIONAL TECHNIQUES: Identification, explanation, questions and answers, demonstration, videos from source
INSTRUCTIONAL MATERIALS: Videos, loud speaker, textbook, pictures
INSTRUCTIONAL PROCEDURES
PERIOD 1-2
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PRESENTATION |
TEACHER’S ACTIVITY |
STUDENT’S ACTIVITY |
|
STEP 1 INTRODUCTION |
The teacher reviews the previous lesson on petroleum |
Students pay attention |
|
STEP 2 EXPLANATION |
He explains the terms cracking and reforming. He states the uses of crude oil
|
Students pay attention and participates |
|
STEP 3 DEMONSTRATION |
He describes natural gas and states its uses |
Students pay attention and participate |
|
STEP 4 NOTE TAKING |
The teacher writes a summarized note on the board |
The students copy the note in their books |
NOTE
PETROLEUM
Cracking
After the fractional distillation process, the separated mixtures have to be cracked down. This means that a long molecule will be split up in smaller parts.
Firstly, single bonds will be broken down. This results into some lone electrons.
The lone electrons form double bonds. Thus, hydrogen will disconnect from the carbon atom. Hydrogen (H2) remains as a side product. The loss of hydrogen in these smaller organic molecules is logical, because when they are lost, more lone electrons remain with what the previous lone electrons can make a bond.
Reforming
After cracking, the molecules are ready to undergo the reforming process.
This is given by the octane number. The octane number is very important in petrol. It tells what the percentage of pure heptane (in the earlier days it was octane – that is why it is called octane number) in petrol is. This is of great importance for the chemical behaviour. The quality of petrol is improved by adding mixtures to pure heptane. The chains of heptane are heated up (where platinum is used as a catalyst). So they can change. After the heating process, it shows a higher amount of branched chains. This increases the octane number.
The petrochemical industry
About 90% of the crude oil produced is used as a fuel to generate electricity and drive motor vehicles. Another 10% is used as petrochemical feed stock.
USES OF CRUDE OIL
1. Used As petrochemical feed stock
2. A source of hydrocarbons (e.g methane, ethane, propane e.t.c). Used for manufacturing:
3. Used for the synthesis of other organic compounds (alcohols, alkanoic acids, ethers, aldehydes, amines e.t.c)
NATURAL GAS
Natural gas is usually found together with crude oil in between rock layers it is predominantly methane (about 90%). Other gases present include ethane propane, butane pentane and a small fraction of carbon dioxide, nitrogen and helium
Packaging as liquefied natural gas (LNG)
Liquefied natural gas (LNG) is natural gas (predominantly methane, CH4, with some mixture of ethane, C2H6) that has been cooled down to liquid form for ease and safety of non-pressurized storage or transport. It takes up about 1/600th the volume of natural gas in the gaseous state.
It is odorless, colorless, non-toxic and non-corrosive. Hazards include flammability after vaporization into a gaseous state, freezing and asphyxia.
The liquefaction process involves removal of certain components, such as dust, acid gases, helium, water, and heavy hydrocarbons, which could cause difficulty downstream. The natural gas is then condensed into a liquid at close
USES OF NATURAL GAS
Natural gas is a non-renewable hydrocarbon used as a source of energy for heating, cooking, and electricity generation. It is also used as a fuel for vehicles and as a chemical feedstock in the manufacture of plastics and other commercially important organic chemicals.
EVALUATION: 1. Explain the terms cracking and reforming
CLASSWORK: As in evaluation
CONCLUSION: The teacher commends the students positively