Homework Help: chemistry

Posted by mangozier on Friday, January 11, 2013 at 10:11am.

Tricky one- my math fails here

(a) A pressure vessel contains a large volume of CO2 gas at 10 atm pressure. A membrane composed of a poly(ether ketone) polymer with thickness 100 microns and net effective area of 100 cm2 covers a small perforated port in the container. The solubility of CO2 at 10 atm is 6.97 x 10-4 moles/cm3 at 35 ∘C. The diffusivity of CO2 in the polymer is known to be 2.29 x 10-8 cm2/s at this temperature. How long will it take for 0.001 moles of CO2 to leak from the container at steady-state? Assume that the amount of carbon dioxide in the surroundings is insignificant. Express your answer in hours

(b) If the diffusivity is observed to double when the temperature is increased by 10 degrees C, what is the activation energy for diffusion? Express your answer in units of eV.

chemistry - alq7, Friday, January 11, 2013 at 10:22pm
I have no idea =/
chemistry - someguy, Sunday, January 13, 2013 at 12:32am
a) 1.74
chemistry - Anonymous, Sunday, January 13, 2013 at 1:32am
how about b
chemistry - lana, Sunday, January 13, 2013 at 5:34am
I've got 1.14*10^19 applying known formula D=D0*exp[−EA/RT]but it's wrong. Who can write a formula for b?
chemistry - Anonymous, Sunday, January 13, 2013 at 7:29am
You have a ratio: D1/D2=1/2 and you know T1 and T2, use it.
chemistry - an, Sunday, January 13, 2013 at 7:56am
39.2 b
chemistry - Anonymous, Sunday, January 13, 2013 at 8:01am
Don't forget to convert your answer in eV
chemistry - martin, Sunday, January 13, 2013 at 8:07am
39.2 is wrong answer. could you please help for the answer of b
chemistry - qpt, Sunday, January 13, 2013 at 8:10am
same here had 39.2 as the wrong answer.
chemistry - martin, Sunday, January 13, 2013 at 8:29am
1ev= 1.69*10^-19 J
chemistry - Anonymous, Sunday, January 13, 2013 at 9:09am
You have a formula D=D0*exp[−EA/kT], you have a ratio D1/D2=1/2 and values of temperatures. Express EA and answer is yours.
chemistry - lana, Sunday, January 13, 2013 at 9:25am
I multiply the Ea in 0.001 mole as the value is in j/moles. Still I don't get and how we apply two temparatures there?
chemistry - Chemical Engineer, Sunday, January 13, 2013 at 9:28am
Stop cheating
after the end of exam period i will tell you the answer
chemistry - Anonymous, Sunday, January 13, 2013 at 9:38am
You have a formula for D1 and for D2, you have a ratio D1/D2=1/2, further only answer)
chemistry - someguy, Sunday, January 13, 2013 at 4:25pm
0.551

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