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SQA National 5 Chemistry Cracking

Cracking

This page covers the following topics:

1. Cracking process benefits
2. Methods of cracking
3. Cracking equations

Cracking involves breaking down long chain alkanes to shorter chain alkanes and alkenes. This reaction is important for obtaining many short chained unsaturated molecules.

Cracking process benefits

Cracking is either done using a catalyst (zeolite) or steam, it can be done in a lab using the apparatus shown.

Methods of cracking

In a cracking equation the reactant will always be a long alkane and the products will be a shorter chain alkane and alkene. When writing equations remember there must be the same number of carbon and hydrogen atoms on both sides.

Cracking equations

1

Complete this equation:

C₁₅H₃₂ β†’ C₁₂H₂₆ + ?

Complete this equation: 

C₁₅H₃₂ β†’ C₁₂H₂₆ + ?

2

What is one advantage of catalytic cracking?

What is one advantage of catalytic cracking?

3

What are the values of x and y in this equation?

Cβ‚‚β‚…Hβ‚…β‚‚ β†’ CxHβ‚„β‚‚ + CyH₁₀

What are the values of x and y in this equation?

Cβ‚‚β‚…Hβ‚…β‚‚ β†’ CxHβ‚„β‚‚ + CyH₁₀

4

Which method requires higher temperatures, catalytic or steam? Why?

Which method requires higher temperatures, catalytic or steam? Why?

5

What are the values of x and y in this equation?

Cβ‚‚β‚€Hβ‚„β‚‚ β†’ CxH₂₆ + Cβ‚ˆHy

What are the values of x and y in this equation? 

Cβ‚‚β‚€Hβ‚„β‚‚ β†’ CxH₂₆ + Cβ‚ˆHy

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