Chemical Forums
Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: Danial on October 16, 2010, 12:08:23 AM
-
(https://www.chemicalforums.com/proxy.php?request=http%3A%2F%2Fimg181.imageshack.us%2Fimg181%2F3628%2Fas6q.jpg&hash=4403d989a3aa9a25d302d5ea88b46fa739a77ad4)
For part i, i used t+=u+/(u+ + u-)
and got 8.6 x 10-8
which is not equal to the u value in my book.
Is that method of finding the answer correct?
for all of part ii all my answers were kind of high
for part a
i used
conductivity at infinite dilution = (z+) (u+ +u-)F
and then found the conductivity at infinit dilution,
the i used the linear expression for conductivity
conductivity = limiting cond + k rootC
and im not sure what to use as k in this question, would it just be 1?
for part ii b
i used the same formula as in part i and found t
then used that t to find I+ using t = I+/I
then found lamba naught the molar conductivity and inifite dilution using lamba0 = Z+Fu+
then with that
i found E by rearanging
lamda0 = I/(ACE) and found E = 79840 which is huggee but the units are consitant
then in part C i found V = lE and the length was 0.01 so i got V = 798 which is also huge
then for part c i found using s = uE
that it moved 3.75m's in 10minutes, which is heaps haha
is my process correct in any way?
my answers seem way too high
thanks in advance
-
I think for part b, you would be expected to get the correct value,
And the rest i'm not sure why but those voltages are huge maybe its a unit error
-
How else could i go about getting the correct value?
-
I found the error in part II b, i had to convert M into mol/m^3
now i have a more realistic volt meter and the rest of the answers seem nicer too.
but for part II a im trying to use the linear expression for molar conductivity, but i dont know what to use as the constant next to root concentration. In an experiement we did the K=-0.0003 but i dont think im supposed to use that in this question,
Could anyone give me a hint in solving that question?
Also with part i, ive done it like 4 different ways with different formulas and the answer isnt = to the literature value, maybe my lecturer just put a incorrect transport number so we wouldnt just look up the answer in the book