As a subject matter expert in the field of chemistry and physics, I am well-versed in the properties of various gases, including oxygen and carbon monoxide. To address the question of which is heavier, we must first understand the concept of molar mass, which is the mass of one mole of a substance. The molar mass of a gas is directly related to its density under the same conditions of temperature and pressure.

Oxygen (O2) has a molar mass of approximately 32 grams per mole. This is because oxygen is a diatomic molecule, meaning it consists of two oxygen atoms bonded together. The atomic mass of a single oxygen atom is about 16, and thus for two atoms, it is 32.

Carbon monoxide (CO), on the other hand, has a molar mass of about 28 grams per mole. Carbon monoxide is also a diatomic molecule, but it consists of one carbon atom and one oxygen atom. The atomic mass of carbon is approximately 12, and when combined with the mass of one oxygen atom, the total comes to 28.

Given these molar masses, we can infer that oxygen is slightly heavier than carbon monoxide on a molar basis. However, when considering the weight of these gases in the atmosphere, we must also take into account the ideal gas law, which states that equal volumes of gases, at the same temperature and pressure, contain the same number of molecules. This means that the density of a gas is directly proportional to its molar mass.

In practical terms, the density of a gas is what determines whether it will rise or sink in the atmosphere. Oxygen, being slightly heavier than carbon monoxide, will tend to be closer to the ground under normal conditions. However, it is important to note that both gases are lighter than air and will diffuse evenly throughout a room, contrary to the myth mentioned.

The concern about carbon monoxide is not so much about its weight, but its toxicity. Carbon monoxide binds to hemoglobin in the blood more effectively than oxygen, forming carboxyhemoglobin, which prevents the blood from carrying oxygen effectively. This can lead to carbon monoxide poisoning, which is a serious and potentially fatal condition.

In conclusion, while oxygen is slightly heavier than carbon monoxide on a molar basis, both gases are lighter than air and will distribute evenly in a room. The primary danger of carbon monoxide is its toxicity, not its relative weight.

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There's a myth that carbon monoxide alarms should be installed lower on the wall because carbon monoxide is heavier than air. In fact, carbon monoxide is slightly lighter than air and diffuses evenly throughout the room.May 30, 2017read more >>