When we breathe we inhale oxygen, O2, and exhale carbon dioxide, CO2, plus water vapor, H2O. Which likely has more mass, the air that we inhale or the same volume of air we exhale? Does breathing cause you to lose or gain weight?
I thought that the air we breathe out has more mass since the water vapor has more mass than the CO2 and O2 gasses. This should cause me to lose weight as I lose water. Is this right? Or am I missing something? Thanks.
I don't know that you are missing anything but I think it answer isn't complete. The air we inhale also has nitrogen (about 80%) and the density of air at STP is about 1.29 g/mL. The air we exhale is CO2 and H2O so that is much more dense I would think, even at an elevated temperature (the body T is about 98 or so F and air is about 75 or so F. I agree that the mass of air we exhale is more likely to weigh more than the air we inhale. I agree that we lose weight when we exhale. But we regain, at least part of it, when we take the next breath in. So yes, you lose water but you also lose CO2 plus the nitrogen taken in with the oxygen.
It isn't used. The nitrogen there dilutes the oxygen in air; otherwise, we would be breathing pure oxygen (along with small amounts of other gases).
When we breathe, there are several components in the air we inhale and exhale, including oxygen (O2), carbon dioxide (CO2), and water vapor (H2O). Let's break it down to understand which likely has more mass.
First, it's important to note that the composition of inhaled and exhaled air is not exactly the same. The air we inhale contains roughly 21% oxygen, 0.04% carbon dioxide, and varying amounts of water vapor depending on humidity levels. The remaining portion consists mainly of nitrogen gas (N2).
During respiration, our bodies use oxygen for cellular processes and produce carbon dioxide as a waste product. Additionally, we exhale water vapor due to the moist environment of our respiratory system.
So, to answer your question, the air we exhale generally has a slightly higher mass compared to the same volume of air we inhale. This is primarily due to the added water vapor content. Water molecules (H2O) do have a greater mass compared to carbon dioxide (CO2) and oxygen (O2) molecules.
However, it's essential to understand that the amount of water vapor and its mass in exhaled air is relatively small compared to the other gases. Therefore, the difference in mass between inhaled and exhaled air is generally negligible.
As for the impact on weight, breathing alone does not cause significant weight loss or gain. The exchange of gases during respiration does not lead to a substantial loss or gain of mass. The water vapor you exhale is a small fraction of your total water content, and any minor fluctuations in water vapor lost through breathing are quickly replenished through regular fluid intake.
In summary, while the air we exhale may have slightly more mass due to water vapor, the overall difference in mass is negligible. Breathing does not cause significant weight loss or gain, as it represents only a small fraction of the body's overall mass and water content.