Chemistry Of Petroleum 3: Distillation Of Hydrocarbons

To introduce how hydrocarbons in crude oil are distilled and treated in the refinery course of to provide helpful materials.


This lesson is part of the Power in a High-Tech World Project, which examines the science behind energy. Energy 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 closer look on the science behind power, be sure to check out the Vitality in a High-Tech World Challenge web page.

This lesson is the third in a sequence of lessons concerning the chemistry of petroleum which can be supposed for upper-stage chemistry students in the eleventh and twelfth grades. You ought to be an experienced chemistry instructor to show these lessons. The aim of these lessons is to introduce excessive-faculty college students to using oil as an energy source in today’s excessive-tech world. Within the Chemistry of Petroleum 1: What are Hydrocarbons? college students will explore hydrocarbons, the molecular foundation of petroleum, and be taught to tell apart between organic and inorganic compounds.

In the Chemistry of Petroleum 2: What Occurs to Hydrocarbons When they Burn? college students will study the various quantities of vitality produced by the combustion of various hydrocarbons.

In this lesson, the Chemistry of Petroleum three: Distillation of Hydrocarbons, college students shall be launched to the distillation and treatment processes by which petroleum is refined to supply helpful fuel oils.

The Chemistry of Petroleum 4: Therapy of Hydrocarbons will assist students discover the chemical treatment processes by which distilled petroleum fractions are transformed to provide helpful fuel oils.

This explicit lesson gives the opportunity to address a variety of misconceptions that college students have concerning the bodily world. Generally, terminology can inadvertently cause students to develop such misconceptions. The time period “fossil fuel can sometimes be deceptive as it implies that crude oil is made from or derived from fossils. In the course of the motivation part of this lesson, it could also be helpful to make clear the difference between a real fossil and fossil fuels. Fossils are the preserved remains or traces of life types from the past, usually via the process of permineralization. Fossil fuels are produced from decayed organic matter that has modified chemically over geologic time because of high ranges of heat and stress. The term “fossil fuel is used for substances such as coal, natural gasoline, and crude oil or petroleum, as a result of the natural life varieties lived millions of years in the past.

One other false impression amongst college students is that crude oil is composed of particular person molecules of diesel, kerosene, and the opposite refined merchandise. This misconception might emerge if students think of the refinery course of as a sieve via which these merchandise are sorted out from crude oil. The analogy of a sieve is a good one if students perceive that the refined products will not be individual molecules, but a collection of chemically similar molecules. In other phrases, there is no single molecule known as diesel, or kerosene, or gentle gases, with a selected chemical system. In contrast, water is a molecule outlined by a specific chemical formula of H2O. Diesel, then again, is a mixture of various molecules that share the same properties. The chemical property that is basically utilized to sort the varied hydrocarbons in crude oil is boiling point. The sieve in the refining course of separates hydrocarbon molecules of comparable size—and due to this fact, similar chemical properties. Specific collections of similarly sized hydrocarbon molecules are referred to as diesel, kerosene, gentle gases, and the opposite various refined products.

When watching Oil Refining: A more in-depth Look, it is useful to additionally handle that the composition and appearance of crude oil will vary depending upon its source. The interactive shows a thick, black, liquid substance; nevertheless, crude oil can be brown, yellow, and even inexperienced relying upon its chemical composition. It also could be present in a semi-strong kind that doesn’t stream easily until after it’s heated or diluted.

Analysis exhibits that students have many misconceptions about heat, temperature, and phase changes akin to boiling. (Benchmarks for Science Literacy, p. 337.) A simple misunderstanding that college students could have is that a substance can change phases (i.e., from liquid to gasoline), while nonetheless remaining intact in its chemical composition. In the steam furnace animation within the distillation course of, level out to college students that the molecular construction of hydrocarbons doesn’t change when they modify part from liquid to gas. It is usually important to point out that this part change shouldn’t be a function of temperature alone. The boiling point of a liquid is determined not solely by heat, but in addition by the atmospheric strain around the liquid. In the event section of the lesson, a possibility is provided to discuss why water boils at a lower temperature at excessive altitudes. This may assist to make clear the misunderstanding that boiling level is a perform of a temperature reading.

So as for students to do this lesson, in addition to the other classes on this collection, they should have prerequisite information of the basics of atoms and their structure. Basic information about atoms might be found on the Atom. Students additionally ought to know primary natural chemistry, together with an understanding of what hydrocarbons are and how they’re named (i.e., nomenclature).


Begin by reviewing what crude oil is, how it’s formed, and its relevance to human lives by having students use their Oil Refining pupil esheet to look at the introductory animation from Oil Refining: A more in-depth Look. The film has an accompanying script that you can print out. The narrator speaks rapidly, so it is a good suggestion to learn the script after watching the movie the primary time. After reading the script, students can watch the film a second time, which is able to facilitate understanding.

Provide the Understanding Crude Oil student sheet to college students as they watch the animation. They should answer the questions on this sheet.

Query 9 provides a chance to explain how petroleum rises to the floor over time. To assist solidify this concept with students, have them do a quick activity with vegetable oil and water (you’ll be able to do that as a demonstration if you want). They should first pour the vegetable oil into a clear glass, beaker, or cylinder. Ask students:

– What occurs when oil and water are mixed?

Now ask college students to pour the water on prime of the oil. The 2 phases will separate quickly. Ask college students:

– Which phase is now on prime?

Clarify to college students that vegetable oil is a mixture of hydrocarbons from plants, similar to kerogen. Make certain that students perceive that vegetable oil shouldn’t be a fossil gasoline like kerogen because it isn’t produced from natural matter thousands and thousands of years previous that experienced excessive pressures and temperatures over time. Tell college students that if the highest of the glass represented the ground, the oil can be sitting on the floor of the earth and would eventually evaporate or be damaged down by bacteria. Place your hand excessive of the glass and inform students that it represents non-porous rock, such as shale. Clarify that in petroleum exploration, a rock that holds back the petroleum from coming out in the direction of the floor is named a cap rock or seal rock. Because the cap rock is non-porous, the petroleum fills up under it like a reservoir. The rocks straight under the cap rock are porous, because the petroleum was able to maneuver by way of those rocks. In petroleum exploration, scientists search for these cap rocks above porous rocks to seek for deposits. If obtainable, pass round a sample of shale rock, stating that it has no pores or openings. A glazed tile can also characterize a non-porous cap rock. Permit college students to pour vegetable oil onto the rock or tile to see that it’ll merely roll off and not be absorbed, simply as with a cap rock.


Have college students proceed to the next a part of the interactive, “Let’s Distill. It is strongly recommended to go through the five hotspots together as a class. This may ensure that students all perceive the basic ideas round distillation and treatment of petroleum.

Point out the yellow barrel labeled “crude oil Tell students that after the petroleum has been extracted from the ground, it is distributed to refineries. The interactive simulates and describes the various chemical processes that petroleum undergoes in an effort to make helpful merchandise.

Ask college students:

– What is crude oil composed of?

Click on on the “Dump Crude Oil” button and then roll over the hotspot and skim the outline. Discuss with students that crude oil is made up of different compounds. Be certain that students do not assume that the various compounds are floating round within crude oil, however that crude oil itself is the gathering of these compounds. Inform students that crude oil will fluctuate in its composition depending on its geographic location. Basically, it is composed of a mixture of straight-chained hydrocarbons and ringed hydrocarbons. Level out that there are some sulfur and nitrogen compounds blended with the hydrocarbons as nicely. Remind college students that kerogen also contained sulfur and nitrogen.

Click on the “Dump Crude Oil button once more. Ask college students:

– The place does the crude oil go?

Before proceeding, present every pupil with a table of hydrocarbon boiling points from Boiling Factors and Structures of Hydrocarbons. Ask students:

– If you look on the “name and “molecular formula columns, what sample do you notice as you go down?

Evaluation the concept of boiling point with college students by having them do a fast hands-on exercise of boiling water with a thermometer positioned within the water. Have students deliver some water to a boil. Once it reaches the boiling point, ask them:

– What is occurring to a substance when it starts to boil?

Students ought to place the thermometer into the boiling water and browse the temperature. A standard misconception among students is that the temperature of a boiling substance will increase because it boils. To help appropriate this false impression, permit college students to see that the temperature of the boiling water stays at a hundred levels Celsius as it boils. One other common false impression is that the boiling level is when a liquid turns into gas, and never vice versa. It is vital to deal with that boiling level is a phase change between liquid and fuel. It is the point when a liquid turns into gasoline and a gas turns into liquid. Level this out to college students by displaying that the boiling water will be considered as liquid turning into gasoline, or gasoline turning into liquid.

Inform college students that on Mount Everest, water boils at sixty nine levels Celsius. Ask college students:

– What makes the summit of Mount Everest totally different from sea degree?

Overview with college students that the boiling point of a substance shouldn’t be a perform of temperature alone. What determines when a substance will change from liquid to fuel is both temperature and the encompassing atmospheric stress. College students are sometimes conscious, by way of their lived experience, that a change in temperature will alter a substance’s phase. For instance, water positioned within the freezer changes into ice, and water that is heated to a hundred levels Celsius boils and turns into a gas. Nevertheless, they often do no make the connection that stress is equally as vital in figuring out the phase of a substance. To assist make this point more clear, ask students to think about a balloon that comprises air molecules. Inform college students that temperature is a measure of heat. If the balloon is heated, the kinetic energy of the molecules contained in the balloon also increases and they begin to break away from each other and transfer faster. Ask students:

– What’s going to occur to the dimensions of the balloon as the heat and corresponding kinetic vitality of the molecules increase?

The barrier of the balloon represents the exterior air strain. It holds the air molecules again from increasing out any further. Sooner or later, because the heat increases, the balloon will burst. That bursting represents boiling because at that time, the pressure inside the balloon turns into equal to the strain outdoors of the balloon. Similarly, a liquid boils when its inner strain is equal to the atmospheric stress.

Going back to the example of Mount Everest, tell college students that water boils at a lower temperature on the mountain (69 levels Celsius) as a result of at that time, its pressure is equal to the low atmospheric stress on Mount Everest. As you descend from Mount Everest and are available to sea stage, the atmospheric pressure is more, so correspondingly more heat is required to cause boiling (one hundred degrees Celsius).

Return again to the table of hydrocarbon boiling factors from Boiling Factors and Structures of Hydrocarbons. Ask students:

– Why do you suppose that the boiling level of alkanes is said to the dimensions of the molecules?

Level out that pentane by way of dodecane are liquid at room temperature. Ask students:

– Of the eight alkanes, which one has the best boiling level?

Evaluate dodecane to an extended spaghetti strand. As a result of its longer length compared to that of a smaller pentane molecule, dodecane molecules will wrap round each other, making it tougher to separate them as a result of of those sturdy forces.

– If all these alkanes had been blended together in a pot, and the temperature was elevated to 250 levels Celsius, what would happen to all these alkanes?

Return back to the interactive. Remind college students that crude oil or petroleum is a mixture of hydrocarbons. The oil is now in the furnace and can be heated. Click on “Start Furnace” and roll over the hotspot and have students give attention to a single hydrocarbon molecule. Ask students:

– If all of the hydrocarbons are superheated, what section will they go into?

Point out that the furnace has now superheated the crude oil parts which are actually in vapor kind. Point out that the vapor has now traveled to the distillation column where the vapor rises. Level out the temperature gradations on the facet of the distillation column.

Roll over the hotspot on the left aspect of the distillation column and level out that the animation shows two different hydrocarbon molecules—methane and cyclopentane. Ask students:

– Which one may have a lower boiling level?

Roll over the hotspot at the top proper nook of the distillation clumn. Show students that all the smaller chained hydrocarbons collect increased up in the distillation column. The collections of these comparable hydrocarbons are known as fractions. Examples of lighter fractions are gasoline and naphtha. Rolling over the hotspot at the decrease right nook of the distillation column will show college students heavier fractions, equivalent to diesel.

Naphtha is a group of hydrocarbons in the C5, C6, and C7 range. These hydrocarbons are all very light, easily vaporized, and kind a clear liquid. Ultimately, after therapy, naphthas are used as solvents in dry cleansing, paint, and other industries that want quick-drying merchandise. Gasoline is a collection of hydrocarbons in the C7 and C11 vary. Diesel is composed of hydrocarbons in the C16 vary. Because they’re larger hydrocarbons, their boiling point is far increased and can condense into liquid decrease within the distillation column where the temperature is increased. Make it possible for college students perceive that the collected fractions are usually not one molecule, but rather a group of hydrocarbons of comparable length, and thus, comparable boiling level temperatures.

Inform college students that distillation is the primary part of the petroleum refining process. The fractions must now undergo treatment for two reasons. First, the hydrocarbon fractions still have substances in them corresponding to sulfur, which have to be removed. Second, some of the longer hydrocarbon fractions must be chemically altered and shortened into smaller chains in an effort to develop into extra useful products.


To assess students’ understandings of the main ideas lined in this lesson, ask them to complete the Assessing Our Understanding of Crude Oil pupil sheet. Tell college students that the ten questions handle misconceptions that most people has about crude oil. Have college students full the sheet individually. Once all the students have chosen their answers, ask college students to work in small teams and share their responses to every query with their group members. Each group should resolve on their collective answer to each query. Provide classroom time for pupil groups to share with one another. Encourage college students to debate misconceptions and why these misconceptions may exist in most of the people. For teachers, this can be a superb alternative to assess if college students are understanding the primary concepts by way of the lessons. The Assessing Our Understanding of Crude Oil trainer sheet offers solutions to the questions.


Explore the usage of vegetable oil, used in the motivation section of this lesson, as a fuel itself. The Bio-Gas Project, from the Vitality Efficiency and Renewable Power site, supplies an intensive, two-week curriculum in which college students learn to make their very own biodiesel fuel from waste vegetable oil.

To additional emphasize the connection between the boiling level of a substance and atmospheric stress, use NASA’s lesson, Testing Your Hypothesis by Boiling Water Beneath Its Boiling Temperature.

Acid Rain: Effects Felt Via the Food Chain, from National Geographic, supplies information about the basic causes and effects of acid rain, including images and what humans can do to decrease its prevalence.

Local weather Change: Basic Data, from the U.S. Environmental Protection Company, supplies comprehensive information on the difficulty of worldwide warming and climate change.

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