Diving into alkanes and haloalkanes, this topic explores how crude... Show more
SociologySign up to see the contentIt's free!
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
1
0
Aasiyah Rahman
04/12/2025
Chemistry
Organic Chemistry- Alkanes and Haloalkanes, alkanes (fractional distillation/cracking)
111
•
4 Dec 2025
•
Understanding Alkanes and Haloalkanes: Fractional Distillation and Cracking Explained
Aasiyah Rahman
@aasiyahrahman
Crude Oil Refining and Cracking
Ever wondered how we get petrol from crude oil? It starts with fractional distillation, where crude oil (mainly alkane hydrocarbons) is heated and passed through a column. Different fractions condense at different heights based on their boiling points. Larger hydrocarbons have higher boiling points due to stronger van der Waals forces, so they settle in lower fractions.
When there's too much of the larger hydrocarbons and not enough of the smaller ones, we use cracking to break C-C bonds. This converts large hydrocarbons into smaller, more valuable products. Thermal cracking uses high temperatures and pressure to produce mainly alkenes for polymers, while catalytic cracking uses a zeolite catalyst at lower temperatures (450°C) to produce branched and cyclic hydrocarbons for cleaner-burning motor fuels.
The combustion of alkanes releases heat energy, making them excellent fuels. Complete combustion (with excess oxygen) produces CO₂ and H₂O, while incomplete combustion produces less energy and forms carbon monoxide, soot, and water. This is why proper air flow is crucial when burning fuels.
Did you know? Branched and cyclic hydrocarbons have higher octane numbers, making them better for engines as they burn more cleanly and efficiently.
Environmental Impact of Combustion
Burning hydrocarbons isn't without consequences. Nitrogen oxides form when atmospheric nitrogen reacts with oxygen at high temperatures inside engines, creating toxic compounds that contribute to acid rain. Similarly, sulphur impurities in fuels produce SO₂ when burned, which dissolves in atmospheric water to form acid rain.
To combat these pollutants, modern vehicles use catalytic converters containing precious metals like platinum and palladium. These converters have a honeycomb structure coated with catalysts that transform harmful exhaust gases (CO, NOₓ, unburned hydrocarbons) into less harmful substances like CO₂, N₂, and H₂O.
The combustion of fossil fuels has significantly increased greenhouse gases like CO₂ in our atmosphere. These gases trap Earth's radiated infrared energy, leading to global warming. Carbon monoxide (toxic), carbon dioxide (greenhouse gas), unburnt hydrocarbons (smog formation), and soot (respiratory problems and global dimming) are all pollutants resulting from hydrocarbon combustion.
Important connection: Understanding the chemistry of fuel combustion helps explain why electric vehicles and renewable energy sources are becoming increasingly important in combating climate change.
We thought you’d never ask...
What is the Knowunity AI companion?
Our AI Companion is a student-focused AI tool that offers more than just answers. Built on millions of Knowunity resources, it provides relevant information, personalised study plans, quizzes, and content directly in the chat, adapting to your individual learning journey.
Where can I download the Knowunity app?
You can download the app from Google Play Store and Apple App Store.
Is Knowunity really free of charge?
That's right! Enjoy free access to study content, connect with fellow students, and get instant help – all at your fingertips.
Most popular content: Hydrocarbons
Most popular content in Chemistry
Most popular content
Can't find what you're looking for? Explore other subjects.
Students love us — and so will you.
4.9/5
App Store
4.8/5
Google Play
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
Best app on earth! no words because it’s too good
Thomas R
iOS user
Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.
Basil
Android user
This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.
Rohan U
Android user
I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didn’t even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as I’m sure you too will see developments.
Xander S
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE THE SCHOOLGPT. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now
Paul T
iOS user
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
Best app on earth! no words because it’s too good
Thomas R
iOS user
Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.
Basil
Android user
This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.
Rohan U
Android user
I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didn’t even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as I’m sure you too will see developments.
Xander S
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE THE SCHOOLGPT. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now
Paul T
iOS user
Understanding Alkanes and Haloalkanes: Fractional Distillation and Cracking Explained
Aasiyah Rahman
@aasiyahrahman
Diving into alkanes and haloalkanes, this topic explores how crude oil is processed into useful products and the environmental impacts of hydrocarbon combustion. Understanding these concepts is essential for chemistry students as they connect directly to energy production, environmental concerns,... Show more
Crude Oil Refining and Cracking
Ever wondered how we get petrol from crude oil? It starts with fractional distillation, where crude oil (mainly alkane hydrocarbons) is heated and passed through a column. Different fractions condense at different heights based on their boiling points. Larger hydrocarbons have higher boiling points due to stronger van der Waals forces, so they settle in lower fractions.
When there's too much of the larger hydrocarbons and not enough of the smaller ones, we use cracking to break C-C bonds. This converts large hydrocarbons into smaller, more valuable products. Thermal cracking uses high temperatures and pressure to produce mainly alkenes for polymers, while catalytic cracking uses a zeolite catalyst at lower temperatures (450°C) to produce branched and cyclic hydrocarbons for cleaner-burning motor fuels.
The combustion of alkanes releases heat energy, making them excellent fuels. Complete combustion (with excess oxygen) produces CO₂ and H₂O, while incomplete combustion produces less energy and forms carbon monoxide, soot, and water. This is why proper air flow is crucial when burning fuels.
Did you know? Branched and cyclic hydrocarbons have higher octane numbers, making them better for engines as they burn more cleanly and efficiently.
Sign up to see the contentIt's free!
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Environmental Impact of Combustion
Burning hydrocarbons isn't without consequences. Nitrogen oxides form when atmospheric nitrogen reacts with oxygen at high temperatures inside engines, creating toxic compounds that contribute to acid rain. Similarly, sulphur impurities in fuels produce SO₂ when burned, which dissolves in atmospheric water to form acid rain.
To combat these pollutants, modern vehicles use catalytic converters containing precious metals like platinum and palladium. These converters have a honeycomb structure coated with catalysts that transform harmful exhaust gases (CO, NOₓ, unburned hydrocarbons) into less harmful substances like CO₂, N₂, and H₂O.
The combustion of fossil fuels has significantly increased greenhouse gases like CO₂ in our atmosphere. These gases trap Earth's radiated infrared energy, leading to global warming. Carbon monoxide (toxic), carbon dioxide (greenhouse gas), unburnt hydrocarbons (smog formation), and soot (respiratory problems and global dimming) are all pollutants resulting from hydrocarbon combustion.
Important connection: Understanding the chemistry of fuel combustion helps explain why electric vehicles and renewable energy sources are becoming increasingly important in combating climate change.
We thought you’d never ask...
What is the Knowunity AI companion?
Our AI Companion is a student-focused AI tool that offers more than just answers. Built on millions of Knowunity resources, it provides relevant information, personalised study plans, quizzes, and content directly in the chat, adapting to your individual learning journey.
Where can I download the Knowunity app?
You can download the app from Google Play Store and Apple App Store.
Is Knowunity really free of charge?
That's right! Enjoy free access to study content, connect with fellow students, and get instant help – all at your fingertips.
1
Smart Tools NEW
Transform this note into: ✓ 50+ Practice Questions ✓ Interactive Flashcards ✓ Full Mock Exam ✓ Essay Outlines
Mock Exam
Quiz
Flashcards
Essay
Similar content
Alkane Reactions Overview
Explore the key concepts of alkane chemistry, including substitution reactions, free radical mechanisms, and combustion processes. This summary covers the initiation, propagation, and termination stages of chlorination, as well as the properties and reactivity of alkanes. Ideal for A-level organic chemistry students seeking to understand the behavior of alkanes in various reactions.
Chemistry12
Chemical Bonding Explained
Explore the fundamentals of chemical bonding, including ionic, covalent, and metallic bonds, as well as intermolecular forces. This summary covers key concepts such as bond types, molecular shapes, electronegativity, and the properties of substances based on their bonding. Ideal for AQA A Level Chemistry students seeking a comprehensive overview of bonding principles.
Chemistry12
Most popular content: Hydrocarbons
Most popular content in Chemistry
Most popular content
Can't find what you're looking for? Explore other subjects.
Students love us — and so will you.
4.9/5
App Store
4.8/5
Google Play
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
Best app on earth! no words because it’s too good
Thomas R
iOS user
Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.
Basil
Android user
This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.
Rohan U
Android user
I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didn’t even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as I’m sure you too will see developments.
Xander S
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE THE SCHOOLGPT. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now
Paul T
iOS user
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
Best app on earth! no words because it’s too good
Thomas R
iOS user
Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.
Basil
Android user
This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.
Rohan U
Android user
I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didn’t even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as I’m sure you too will see developments.
Xander S
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE THE SCHOOLGPT. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now
Paul T
iOS user