[AKTuffin]

I am a first year chemical engineer and we have this homework problem for class. I am unsure if I missed something in class or if I should have had more chemistry background before taking this intro. class. So, I was wondering if someone could help me connect somethings.

The problem is this:
The vapor pressure of a liquid i, p_i,v(mmHg), as a function of temperature T (K) may be described by the Antoine equation: p_i,v = A - B/(T + C)  where for i = water, the constants are: A=18.3036, B=3816.44, C=-46.13. Plot the saturation mole fraction of water vapor in air, x_i,S as a function between 20^oC and 100^oC. The RH is, in fact, the ratio of the actual mole fraction of water in air, x_i, to the saturation mole fraction, x_i,S, at a given temperature. RH = x_i/x_i,S. Thus, calculate mole fraction x_i n a hot muggy day when RH=80% and the temperature is 37^oC.


I started out by plugging in the temperature and the constants into the Antoine equation. p_i,v = 18.3036 - ( 3816.44/ (310-46.13) ) and found p_i,v = 3.8402 mmHg
I also know that RH=80% so .80=x_i/x_i,S and I am solving for x_i.
So, my question is, did I attempt this wrong or is there someway that I missed to connect p_i,v to x_i,S.

Sorry if this seems a bit easy, but I seem to have definatly missed something in class.