Final answer:
Mercaptan is the chemical added to natural gas to give it a distinct odor. This helps in detecting gas leaks due to its strong, sulfur-like smell, despite the primary component of natural gas, methane, being odorless.
Step-by-step explanation:
The chemical that is added to natural gas to give it a distinct odor is mercaptan. Specifically, compounds such as tert-butyl mercaptan, whose condensed structural formula is (CH3)3CSH, are used. The odor of mercaptans is similar to that of rotten eggs and is highly detectable by the human nose at very low concentrations, which is essential for safety reasons as natural gas is odorless by itself. When there is a gas leak, the smell helps in detecting it early, potentially preventing accidents.
Natural gas is predominantly composed of methane (CH4), which is an odorless and highly combustible hydrocarbon. Methane's chemical and physical properties make natural gas a valuable fuel source, but also necessitate the need for safety measures, such as the addition of a strong-smelling substance like mercaptan, to detect leaks.