Making Petrol Flashcards
In the 1920s what was discovered in relation to knocking in engines.
It was discovered that adding small amounts of a lead compound called tetraethyl lead, Pb(C2H5)4, helped reduce the amount of knocking in engines
What is Pb(C2H5)4 said to be?
An anti-knock additive
Why has leaded petrol been phased out?
Awareness of the potential health hazard caused by poisonous lead pollution from car exhausts
What has leaded petrol been replaced with?
Unleaded petrol
Other than it’s toxicity, why has lead been replaced in petrol?
It poisons the metal catalysts in the catalytic converter of the car
Why was adding lead compounds to petrol an easy solution to the problem of knocking?
Since it meant that the petrol did not have to contain compound with high octane numbers
What is the octane number of ‘straight run’ petrol?
70
How many ways are there to increase the octane number of petrol?
Four
Name the four ways to increase the octane number of petrol?
Isomerization
Catalytic cracking
Dehydrocyclisation
Adding oxygenates
What is added to petrol during winter months so that the petrol vaporises more easily in the carburettor or fuel injector system?
More volatile components such as butane and pentane are put in the petrol during winter
Why are more volatile components such as butane and pentane added to the petrol in winter?
So that the petrol vaporises more easily in the carburettor or fuel injector system
Why are few volatile hydrocarbons added to petrol during summer?
To prevent loss of petrol from the petrol tank by evaporation
