What is the relationship between relative humidity and temperature?

[leena19]

Homework Statement

Temperature of a closed room is 15 degree celsius (T₂₈₈).Relative humidity(RH)at 15degree celsius =60%
Find the RH when the temperature is 20 degrees.
S.V.P at 15 degrees celsius=12.67mmHg
SVP at 20 degree celsius = 17.36mmHg
(ans:45%)

Homework Equations

The Attempt at a Solution

RH= [Partial pressure at 15 degree celsius(P₁₅)/SVP at 15]*100%

P₁₅V = m₁rT₂₈₈ ----------(1)
p₂₀V=m₂rT₂₉₃ -----------(2)

I get the answer when i take m₁ as equal to m₂,but I don't understand why they should be equal.
Doesn't m,the mass of water vapour present in the room increase with temperature?

Thanx

 

[tiny-tim]

Hi leena19!

Temperature of a closed room is 15 degree celsius …
…
Doesn't m,the mass of water vapour present in the room increase with temperature?

Always study the question …

it's a closed room! ​

Where would the extra mass come from?

 

[leena19]

Ah!OK.
Thank you very much!