Technical Standards and Safety Authority (TSSA) G3 Practice Exam

Which substance is deemed inert and absorbs heat during the combustion process?

1. Carbon dioxide

2. Ethyl mercaptan

3. Oxygen

4. Nitrogen

The correct answer is: Nitrogen

The substance that is deemed inert and absorbs heat during the combustion process is nitrogen. In combustion reactions, nitrogen does not participate actively; it remains chemically unchanged and acts mainly as a filler gas in air. It can, however, absorb some of the heat produced by combustion, which helps to moderate flame temperatures and control the rate of combustion. Nitrogen's inert nature and its ability to absorb heat play a crucial role in various combustion processes, contributing to the efficiency and stability of fuel combustion systems without altering the combustion chemistry. This characteristic makes it pivotal in mitigating the risks associated with high-temperature reactions and the formation of undesirable byproducts. While carbon dioxide, ethyl mercaptan, and oxygen have significant roles in combustion, they do not fit the criteria of being inert. Carbon dioxide is a combustion product that reflects how fuel has reacted. Ethyl mercaptan is a gas often added to natural gas for odorization, and oxygen is a reactive element that is essential for the combustion process.