The tempareture and humdity of air are `27^(@)C` and 50% on a particular day. Calculate the amount of vapour that should be added to 1 cubic metre of air to saturate it. The saturation vapour pressure is 3600Pa.

Explanation

` R_H = VP/SVP`
` Given, 0.50 = VP/3600 `
`rArr VP = 3600 xx 0.50`
`Let the extra pressure needed be P`
So, ` P = (m/M) xx (RT/V) `
` = (m/18) xx (8.3 xx 300 / 1)`
Now, ` m/M xx 8.3 xx 300 xx 3600 xx 0.50 `
= 3600
` [ air is saturated i.e. RH = 100% = 1`
or VP = SVP]
` rArr m= ((36-18)6/8.3) `
` = (18 xx 6/8.3) = 13 gm ` .