Chemical Engineering - Mass Transfer - Discussion

The weight of 1 m3 of humid air is typically less than the weight of 1 m3 of dry air under the same conditions. This is because humid air contains water vapour, which has a lower molecular weight than the other gases in the air, such as nitrogen and oxygen.

As a result, the addition of water vapour to air reduces its overall density and weight.

However, the exact weight difference between humid and dry air depends on the specific conditions of temperature, pressure, and humidity.

Water vapor molecules, which are one oxygen atom with a weight of 16 and two hydrogen atoms each with a weight of 1, add up to a molecular weight of 18, which is much lighter than the nitrogen and oxygen they displace when they evaporate into air.

The Weight of water molecule is less then nitrogen and co2 hence when water vapour will displace the component of air definitely it would become lighter.

We know that density of air 1.29kg/m3 and density of water = 1kg/m3 so humid air 1m3 is less than 1m3 of dry air.

Humid air density is low compare to dry air. So therefore weight of humid air is less.

The density of water is 1000 kg/m^3.