How do you determine the density of water vapor at different temperatures?

1 Answer
Jun 18, 2018

see below


you can consider water vapor as an ideal gas , so you can write the ideal gases law
#P xx V = n xx R xx T#
P= pressure
V= volum
n= number of mol (n= mass in g/ MM)
R= universal costant of ideal gases
T= temperatur in K
so you can write the ideal gases law in this way
#P xx V = (m/(MM)) xx R xx T#
density is mass divided volume #d= m/V#
and riarranged the equation you have
#d= m/V= (Pxx MM) /(R xx T)#
where you can see that increasing temperature, d decreases.
Moreover as the MM of water (18g/mol) is less than MM of air (about 29 g/mol), vapor has a less density tthan air