Cracking Question: Chemistry (1 Viewer)

[Mr_Kap]

The dot point on cracking says:
"identify the industrial source of ethylene from the cracking of some of the fractions from the refining of petroleum"


Is it sufficient just to learn about catalytic cracking or do i need to know thermal cracking as well?

 

[Mr_Kap]

alright thx.

 

[Mr_Kap]

Another question: On Ahmad Shah's Chemistry Notes it says that catalytic cracking can only occur in just over atmospheric pressure, but in the student's guide to hsc chemistry it says AT atmospheric pressure. So which one is it?

 

[Mr_Kap]

You would need to know both. But it's also good to remember that the separation of petroleum is done through fractional distillation; you would've learnt this in year 11. Then you would comment that for the bigger products it can be broken down into smaller length chains via cracking (either catalytic or thermal).

That's the general gist of what the dot point is about, but there's nothing difficult about it as it's just more memorisation.

Do we need to know which one is better, like how thermal cracking COMPLETELY decomposes alkane into ethylene and other short chains and Catalyyic cracking incompletely decomposes large molecules into ethylene, so it is insufficient in meeting the demands of the industry?

 

[Kaido]

Yes, you need to know the exact process and products yielded.
Be sure to throw in the name of the catalyst too

 

[pomsky]

Do we need to know which one is better, like how thermal cracking COMPLETELY decomposes alkane into ethylene and other short chains and Catalyyic cracking incompletely decomposes large molecules into ethylene, so it is insufficient in meeting the demands of the industry?

Yep and yep to pretty much all your questions. Because the syllabus is vague at times, whatever you feel you 'may' need to know is probably something that you will need to know. If the syllabus doesn't mention one thing entirely i.e positron emission (in nuclear), then you won't need to know it.

It's always better to know more about something than less of it. Just in case, lol.

 

[Drsoccerball]

You would need to know both. But it's also good to remember that the separation of petroleum is done through fractional distillation; you would've learnt this in year 11. Then you would comment that for the bigger products it can be broken down into smaller length chains via cracking (either catalytic or thermal).

That's the general gist of what the dot point is about, but there's nothing difficult about it as it's just more memorisation.

Are you sure Thermal cracking is used to make ethene ?

 

[Drsoccerball]

I'm 100% certain of it.

Why?

gap in my knowledge sorry ahahah

 

[Chris_S]

Yeah hawk is correct the one's in the syllabus are thermal and catalytic cracking. Thermal cracking is the one where instead of using a catalyst they use high temperatures of around 700C - 1000C