Help settle a bet.

[osarusan]

I know this isn't the kind of post this forum is used to, but it seemed too insignificant to go into "off topic". Hope somebody can help me out.

A friend and I have a bet we need settled.

The issue is how long it will it take for a glass of water (about 400 mls) to evaporate at room temperature (18-24 degrees I guess), when left completely alone.

He says less than 3 months, I say more.

I've googled various combinations of keywords, but with no success.

Could anybody point me in the direction of concrete proof on the issue (only if I'm right of course)

[jebus]

Osarusan I can safely say that I hope there isn't one person on here that knows a website that will give you that answer off the top of the head, I really can :p

[strangeirish]

E = A * Km * (Mw * Pv)/(R * T) (kg/s)

where E = evaporation rate, in kg/s, A = area of the evaporating container, in m^2, Km = mass transfer coefficient, in m/s, Mw = molecular weight of the selected substance, in kg/kmol, Pv = vapor pressure, in Pa (from the partial pressure table for the selected chemical), R = the gas constant,if any (8314 J/(kmol K)), and T = ambient temperature, in K.

Now, you have to calculate for wind, assuming little or none inside
Km = 0.0048 * U^(7/9) * Z^(-1/9) * Sc^(-2/3) (m/s)
where U = wind speed at a height of 3m, in m/s, Z = the pool diameter in the along-wind direction (m), and Sc = the laminar Schmidt number for the selected chemical.
It estimates the Schmidt number, which is a unitless ratio, as:
Sc = (v/Dm)
where v = the kinematic viscosity of the air, assumed to be 1.5 x 3^-5 m^2/s, and Dm = the molecular diffusivity of the selected chemical in air, in m^2/s.

To calculate the molecular diffusivity of the selected chemical in air, is m^2/s^-1 as:
Dm = D(H2O) * [Mw(H2O)/Mw(chem)]^(1/2) (m^2/s)
where D(H2O) = the molecular diffusivity of water (2.4 x 3^-5 m^2/s at 24°C), Mw(H2O) = the molecular weight of water (0.0004kg/kmol), and Mw(chem) = the molecular weight of the selected chemical, if any, in kg/kmol.

The ultimate problem here is that, people today have too much feckin' time on their hands!



So, five months and 8 days.:D:D:D

[gilberto_eire]

ye could always just do it youselves...put a glass up on top of a cabinet or something? :D:D

[osarusan]

ye could always just do it youselves...put a glass up on top of a cabinet or something?

true, but it kind of kills the "I told you so" effect when you have to wait 3 months.


A whole load of mumbo jumbo that went way above my head......

So, five months and 8 days.:D

Excellent.