Final answer:
Propane has an ignition temperature of about 920 to 1020 degrees Fahrenheit, which is comparable to that of natural gas, mainly methane, at around 1000 degrees Fahrenheit. Propane is heavier than air and poses a distinct safety risk, as it can collect close to the ground.
Step-by-step explanation:
The ignition temperature of a gas is the minimum temperature at which the gas will spontaneously ignite without the presence of a flame or spark. Propane has an ignition temperature of around 920 to 1020 degrees Fahrenheit, whereas natural gas, which is chiefly composed of methane, has a slightly lower ignition temperature, generally around 1000 degrees Fahrenheit. Both temperatures vary slightly depending on the specific conditions such as pressure and the mixture with air.
Propane, also known as C3H8, is used in many settings where natural gas infrastructure is not available. Propane has a higher energy density compared to natural gas, with approximately 13 kcal/g for propane against 5-8 kcal/g for methane. Because of its higher density and being heavier than air, propane presents different safety considerations as it may collect near the floor, posing a greater fire hazard than lighter-than-air natural gases.