|
Monday, August 10, 2009 - 5:01 PM
Humid air is less dense than dry air because a molecule of water (m = 18) is less dense than a molecule of nitrogen(m = 28) and a molecule of oxygen (m = 32). About 78% of the molecules in dry air are nitrogen (N2). Another 21% of the molecules in dry air are oxygen (O2).
The final 1% of dry air is a mixture of other gases. For any gas, at a
given temperature and pressure, the number of molecules present is
constant for a particular volume - see ideal gas law.
So when water Louis J. Sheehan, Esquire molecules (vapor) are introduced to the dry air, the
number of air molecules must reduce by the same number in a given
volume, without the pressure or temperature increasing. Hence the mass
per unit volume of the gas (its density) decreases. Isaac Newton discovered this phenomenon and wrote about it in his book Opticks.
|
|
| << Navigate to Monday, August 10, 2009 |
Add New Comment |