１９９２ chem ce

wing

2010-03-02 4:52 am

1992 1(c)(III)(1)(II)
Leaded petrol has been used for a long time in Hong Kong.In April 1991,unleaded petrol was introduced.
Why is petrol leaded?
Answer:It is to increase the octane number of petrol
Would you please tell me why we should increase the octane number of petrol?

回答 (1)

老爺子

2010-03-02 8:33 am

✔ 最佳答案

Octane number of a petrol fuel indicates the efficiency of the petrol fuel.

A petrol fuel with a higher octane number would burn more slowly and smoothly. Consequently, a higher percentage of energy released in burning of this petrol fuel is used to drive the car.

A petrol fuel with a lower octane number burns rapidly. Pre-ignition occurs and some energy released in burning of the petrol fuel is used to make the "vibration" of internal combustion engine, and this is called "knocking".

("Octane number" is out of the present HKCEE syllabus.)

參考: 老爺子

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