Relative humidity calculations.

by maistral
Tags: calculations, humidity, relative
 P: 72 This is totally pissing me off, I don't know what the heck am I doing wrong. Alright, so I was given a temperature of 30°C at 30% relative humidity. I have to get the absolute humidity- So I used Antoine; log(P)=7.96681-1668.21/(228+30); P = 31.6869mmHg. 0.3 x 31.6869 = 9.41517; 9.41517/(760-9.41517) = 1.25x10^-2. Apparently the correct answer is 7.86x10^-3; and an air-water psychrometric chart says 0.008. What on earth am I doing wrong? EDIT: Nevermind, I forgot that I have to multiply y 18/29.