To introduce how petroleum fractions are chemically treated within the refinery process to produce useful materials.
Context
This lesson is a part of the Vitality in a High-Tech World Mission, which examines the science behind energy. Power in a Excessive-Tech World is developed by AAAS and funded by the American Petroleum Institute. For more classes, actions, and interactives that take a more in-depth look at the science behind vitality, be certain to take a look at the Power in a High-Tech World Undertaking web page.
This lesson is the fourth in a sequence of lessons about the chemistry of petroleum which can be supposed for higher-stage chemistry students in the eleventh and twelfth grades. You should be an experienced chemistry trainer to show these lessons. The purpose of those classes is to introduce high-school students to the usage of oil as an vitality supply in today’s excessive-tech world. In the Chemistry of Petroleum 1: What are Hydrocarbons? college students will discover hydrocarbons, the molecular basis of petroleum, and learn to tell apart between natural and inorganic compounds.
Within the Chemistry of Petroleum 2: What Occurs to Hydrocarbons Once they Burn? students will examine the varying quantities of energy produced by the combustion of different hydrocarbons.
Within the Chemistry of Petroleum 3: Distillation of Hydrocarbons, students might be introduced to the distillation processes by which petroleum is refined to supply useful petroleum fractions.
The Chemistry of Petroleum 4: Treatment of Hydrocarbons will help students discover the chemical remedy processes by which distilled petroleum fractions are transformed to provide helpful gas oils.
This explicit lesson is a continuation of lesson 3, which taken collectively complete the crude oil refining course of. Lesson 3 concludes with the crude oil being separated into petroleum fractions, based on the relative boiling factors of the hydrocarbons in the original crude oil. On this lesson, college students discover how these petroleum fractions are handled chemically to provide useful fuels which are familiar to them, comparable to diesel, jet gas, and gasoline.
As college students discover the interactive, they could also be overwhelmed with the quantity of terminology and reactions associated with the remedy process. Students do not have to know or memorize the details of these reactions; quite, they need to obtain a common understanding that a series of chemical reactions are necessary in producing the fuels which can be used on an on a regular basis basis.
As in lesson 3, this activity offers a possibility to clarify the common false impression that crude oil is composed of particular person molecules of diesel, kerosene, and the other refined merchandise. By the end of those lessons, college students ought to perceive that there is no such thing as a single molecule often called diesel, or kerosene, or light gases, with a specific chemical formula, like H2O. Gas oils, like diesel, are a mixture of different molecules that share comparable properties. The 2 most important properties shared in a petroleum fraction are the number of carbons in a molecule and the boiling level.
So as for college students to do that lesson, in addition to the opposite classes on this sequence, they should have prerequisite knowledge of the fundamentals of atoms and their construction. Fundamental details about atoms could be discovered on the Atom. Students additionally ought to know primary organic chemistry, including an understanding of what hydrocarbons are and how they’re named (i.e., nomenclature).
Motivation
Begin by asking students: “We know that petroleum is used to make gasoline. But what different merchandise are made from petroleum?” Ask students to brainstorm in teams, every group generating a list of at the very least ten gadgets that they’ve seen or used up to now 24 hours which can be petroleum products. An inventory of items will be discovered at: Just a few Products Made from Petroleum.
As student groups share their product objects, generate a category checklist. Point out that these things and plenty of extra are all made with fuels derived from crude oil or petroleum. Ask college students:
– How do you suppose our use of petroleum merchandise has modified over time?
– Given the high buyer demand and the truth that crude oil is a limited useful resource, how do you assume refineries make the most out of the crude oil they’ve?
Growth
Assessment with college students the primary phases of crude oil refinement and therapy by making a flowchart. At the start of the flowchart, write the phrases “crude oil.” At the end of the flowchart, place the checklist of products generated by the students. Begin to fill within the flowchart by asking students what happens to crude oil as soon as it is situated within the earth. Next steps ought to embody extraction and taking the crude oil to a petroleum refinery. As soon as at the refinery, the crude oil undergoes the distillation process. The outcomes of distillation are petroleum fractions. Ask college students, “Describe what has occurred to the hydrocarbons within the distillation process.”
Now students ought to assessment the Oil Refining: A more in-depth Look interactive by watching the introductory video and going through the distillation course of. The movie has an accompanying script you could print out. The narrator speaks rapidly, so it’s a good suggestion to learn the script after watching the movie the primary time. After studying the script, college students can watch the film a second time, which can facilitate understanding.
– What chemical property was used to separate the hydrocarbons in the distillation course of?
Undergo the seven fractions, emphasizing that the fractions are composed of a mixture of hydrocarbons, and are not composed of a single molecule. For instance, kerosene is a mixture of hydrocarbon molecules from the original crude oil that include between 10-16 carbons. Because of this there are hydrocarbons in the kerosene fraction that comprise 10 carbons and others that include eleven, and so forth by way of 16.
Point out that via the distillation course of, the hydrocarbons have not been altered or modified in any manner; they’ve merely been separated by measurement utilizing the chemical property of boiling point variations. This can be a bodily change. On the flowchart after distillation and before the scholars’ list of everyday merchandise and oils, write the word “remedy.” Define for students that therapy is the sequence of chemical reactions and applied sciences to change the distilled fractions to make useful and marketable oils.
Enable students to discover the therapy section of the interactive on their very own using the Therapy of Hydrocarbons scholar esheet. College students can answer the questions using the Treatment of Hydrocarbons pupil sheet. Answers are available on the Treatment of Hydrocarbons trainer sheet. Evaluate the questions together as a category. By way of discussion and review of the guiding questions, clarify that there are three completely different therapy processes, usually. These are:
1. Removing impurities in the hydrocarbons, comparable to metals and sulfur
2. Breaking down massive, heavy hydrocarbons
3. Reshaping or building hydrocarbons from smaller ones
The objective of these processes is to make useful products, reminiscent of diesel, gasoline, jet gas, and asphalt. In the end, these final products are not individual molecules, but blends of handled hydrocarbons of various lengths and structures.
Undergo examples of every of the three processes. Begin with the primary course of (Eradicating impurities in the hydrocarbons) by asking students:
– What are the 2 processes that are used to take away sulfur?
Tell students that the general concept behind hydrotreating is so as to add hydrogen gas at high strain and temperature to the petroleum fractions. The oil and hydrogen then enter a reactor loaded with a catalyst.
Ask students:
– What’s a catalyst?
In hydrotreating, a metal surface is normally used as a catalyst. These metals embrace palladium, nickel, platinum, cobalt, and iron. Draw a common reaction system for students to grasp hydrotreating.
S + H2 (g) H2S (g)
(Catalyst, heat, and pressure)
If doable, challenge the therapy web page of the interactive for the class. Click on one of many fuels and then on the hydrotreating box to point out college students an instance of one of many sorts of reactions that occur within the hydrotreating unit. Solid sulfur is converted to hydrogen sulfide gas, which is then eliminated.
S8 (s) + 8H2 (g) 8H2S (g)
(Catalyst, heat, and stress)
Inform students that the hydrotreating course of also removes nitrogen compounds, which if not removed, would react with the oxygen in the air and produce nitric acid (HNO3).
Begin describing an example of the second course of (Breaking down giant, heavy hydrocarbons) by asking students:
– Do large hydrocarbons have high or low boiling points? Why?
Write the components for docosane on the board: C22H46, and inform students that this large hydrocarbon is found in the gas oil fraction after distillation. The gas oil fraction is composed of a mixture of hydrocarbons with 20-70 carbons. If potential, venture the remedy web page of the interactive in front of the classroom and click on on the pink circle next to “gas oil.” Then click on on the throbbing yellow circle within the gas oil pipe to show the chemical structure of docosane. Ask college students:
– What’s the first treatment process for the gas oil fraction?
Tell college students that cracking processes break down heavy hydrocarbons (you might want to make use of the time period massive hydrocarbon molecules) into lighter merchandise (smaller hydrocarbon molecules). Various kinds of cracking processes are used. Concentrate on catalytic cracking, telling college students that this course of uses high heat and a catalyst to break bigger molecules into smaller, more helpful ones. Draw the next reaction to show college students how catalytic cracking works:
C22H46 + heat + catalyst C12H26 + C6H12 + C4H8
The catalyst used is often silica or alumina. Within the above response, docosane is transformed to dodecane, cyclohexane, and butene. The smaller hexane and butene could be combined with different smaller compounds to make gasoline inventory. The bigger dodecane is a part of diesel inventory, which can be used to gas ships and factories.
Describe an example of the third course of (Reshaping or building hydrocarbons from smaller ones) by clicking the pink circle subsequent to “mild naphtha” on the treatment page of the interactive. Doing so will present two treatment processes: hydrotreating and isomerization. Ask college students:
– Are the hydrocarbons in gentle naphtha large or small comparatively?
Inform students that mild naphtha is a mixture of mostly pentane and hexane. Have college students draw the chemical constructions of pentane and hexane. If possible, provide fashions of every construction. Ask students:
– What’s an isomer?
Write the next response on the board:
C5H12 C5H12
Tell students that this is the response for pentane to isopentane. Ask college students to attract the chemical structure of isopentane. Utilizing the model for pentane, remove the fifth carbon from the chain and transfer it to the second carbon. This new construction is isopentane (additionally known as methylbutane or 2-methylbutane), which has the same chemical components as straight-chained pentane. Inform college students that this isomerization is essential in the petroleum remedy process because isomers improve the quality of gasoline versus the straight-chained molecules. In actual fact, isomers enhance the octane score for gasoline.
Assessment
Have students work in teams to decide on one among the top products of the crude oil distillation and remedy course of: diesel, kerosene, gasoline, jet gas, or asphalt. Ask every group to develop a presentation that discusses how their closing product is formed. As they’re doing this exercise, they need to make sure to categorise every step as a bodily or chemical change. Their data should draw upon all aspects of the interactive, together with the film. Their shows ought to begin with the tiny sea plants living thousands and thousands of years ago and transfer through the strategy of forming kerogen, and finally petroleum. Remind students to incorporate drilling before moving into the distillation and remedy process. Students should embody a movement chart in their shows. Encourage students to use completely different strategies of displaying their info. For example, students might select to current a storyboard, comic guide, PowerPoint, essay, or a brief movie. Assess college students based mostly on their holistic understanding of how helpful gas oils are made from crude oil by means of a collection of essential chemical processes.
Extensions
Have students explore what octane ratings for gasoline signify about the product. There are various misconceptions that college students might have. After a lesson, encourage students to survey their parents, teachers, and other drivers about what they find out about octane ratings of gasoline. You and your students can overview Discovering the Science of Petrol to study extra about octane.
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