Question

The tetraethyl lead mixed in petrol works as:
A. Cooling agent
B. Anti-knocking agent
C. Bleaching agent
D. None of the above

Answer 1

Hint: We must know that the tetraethyl Lead has a chemical formula \[{\left( {C{H_3}C{H_2}} \right)_4}Pb\]. It is a fuel additive used to enhance the vehicle performance and economy.

Complete step by step answer: So let’s start our discussion about tetraethyl lead or known as TEL. It is an organic lead compound with a chemical formula \[{\left( {C{H_3}C{H_2}} \right)_4}Pb\].
It is known as a fuel additive due to its patented octane rating booster that boosted engine compression and in turn enhanced vehicle performance and economy.

Although this fuel was very much in controversy mainly due to the pollution effect caused by its use. TEL was known to cause soil and air toxicity by accumulation.
- TEL was completely phased out from Indian roads by the year 2000.
- TEL was used for 2 advantages which are valve wear preventative and anti-knocking properties.
So let’s talk about this anti-knocking property in detail.
Engine knocking is defined as the uncontrolled combustion caused in the engine, to prevent this to happen a sufficient octane rating fuel is used in a gasoline-fuelled reciprocating engine.
TEL was responsible for this anti-knocking effect. As mentioned earlier, it was added as an anti-knock agent in the fuel.
TEL allows the use of higher compression ratios thus increasing efficiency as well as peak power. Changing the quantity or amount of additives added in the fuel acts as an inexpensive method to control the octane ratings or octane number of a fuel. Here fuel can also be referred to as petrol.
Hence, the correct answer for this question would be B) anti-knocking agent.

Note: There are many anti-knocking agents being used for petrol and diesel some of the examples beside TEL are Methylcyclopentadienyl manganese tricarbonyl (MMT), etc. Some of the examples for antifreeze agents in petrol and diesel engines are propylene glycol or a mixture of propylene glycol and ethylene glycol.