Posted by T on Saturday, December 15, 2012 at 2:49am.
A latex balloon, wall thickness 3.091 x 10-4 m, contains helium at a concentration of 0.7 kg m-3. Under these conditions the total surface area of the balloon is 0.52 m2. The diffusion coefficient of He in latex at room temperature is 4.9 x 10-9 m2s-1. Calculate the rate of helium effusion (in g/hr) from the balloon.
This is a question from the second midterm of 3.091x by edx. Stop cheating, it's silly and pointless.
42.8
How did you get it? could you show the data in the formula? Thank you
THE FORMULA
A latex balloon, wall thickness 3.091 x 10-4 m, contains helium at a concentration of 0.94 kg m-3. Under these conditions the total surface area of the balloon is 0.53 m2. The diffusion coefficient of He in latex at room temperature is 4.9 x 10-9 m2s-1. Calculate the rate of helium effusion (in g/hr) from the balloon.
Fick’s Law
M= -D•(Δρ/Δx)•A,
where
M = m/t = mass flux [kg/s],
D= 4.9•10 ⁻⁹ m ²/s is the diffusion coefficient (diffusivity) [m²/s],
Δρ/Δx is the gradient of density [kg/m⁴],
A is the area [m²].
M= - 4.9•10⁻⁹•(0 - 0.35)/3.091•10⁻⁴)•0.88 =
4.9•10⁻⁹•0.35•0.88/3.091•10⁻⁴=
=4.88•10⁻⁶ kg/s= 17.58 g/hr
thanks stud
HOW CAN I SOLVE WITH THESE NUMBERS?
A latex balloon, wall thickness 3.091 x 10-4 m, contains helium at a concentration of 0.82 kg m-3. Under these conditions the total surface area of the balloon is 0.5 m2. The diffusion coefficient of He in latex at room temperature is 4.9 x 10-9 m2s-1. Calculate the rate of helium effusion (in g/hr) from the balloon.
how do you approach and solve it?