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Complete the equation for the cracking of C,,H 14° °30° CygHyg CyHg
See it on the paper →Cracking is used to make propene. Describe how propene is made by cracking. Include the conditions used.
See it on the paper →Describe how large alkane molecules produced by fractional distillation are changed into smaller alkene molecules.
See it on the paper →The large alkane C 22 H 46 is changed into butane and an alkene. Complete the balanced symbol equation for this reaction. C 22 H + butane alkene
See it on the paper →State the purpose of the catalyst in the cracking of a saturated hydrocarbon.
See it on the paper →break down large hydrocarbon alkane molecules into smaller alkene and smaller alkane molecules.
See it on the paper →Name the process that produces small alkene molecules from larger alkane molecules.
See it on the paper →Fractional distillation makes too much fuel oil and not enough petrol. Cracking is a process that breaks large molecules into smaller molecules. Some fractions are cracked. Suggest why cracking is useful.
The term cracking was not widely known as the correct process. More candidates understood that the process involved high temperatures. The term catalytic cracking was seen quite often.
— Examiner report, May/June 2025, 0654/41 Q8(b)(i) (Cambridge)
The correct formula for butane was only sometimes seen. The most awarded marking point was recognising that the formulas quoted for butane and an alkene balanced with the large alkene given.
— Examiner report, May/June 2025, 0654/41 Q8(b)(ii) (Cambridge)
Cracking was well known as the process. Combustion was a popular incorrect response.
— Examiner report, February/March 2024, 0654/32 Q2(a)(i) (Cambridge)
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During cracking, dodecane, C 12 H 26 , can make octane, C 8 H 18 , and ethene, C 2 H 4 . Write the balanced symbol equation for this reaction.
See it on the paper →State the name of the chemical reaction that makes alkenes from alkanes.
See it on the paper →Name the process that converts alkanes into alkenes.
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