what does the following mean? Calculate single ion activity coefficients for Cs^+, Cd^2+,Al^3+ and dissolved H2CO3 as a function of ionic strength for 10^-4 lessthan equal I lessthan equal to1?

Question

aaronq · Answer

they want the activity coefficients for the different ions considering the ionic strength given

anonymous · Answer

so from 10^-4 to 1?

anonymous · Answer

i am using the davies equation to calculate it, so each time I have to change the ionic strength
th?

aaronq · Answer

hm no that doesn't seem right. i don't know what they mean by $10^{-4} \leq 1$, it doesn't make sense.

anonymous · Answer

its
$$10^{-4}\le I \le1$$

aaronq · Answer

oh, i thought you typed the same thing twice accidentally. I guess they want it within that range?  thats a large range though. I would graph it

aaronq · Answer

on excel of course

anonymous · Answer

we have to calculate and plot it

aaronq · Answer

i guess do a few points for each ion and then plot it

anonymous · Answer

can I show you the full question ? please tell me what I should do

aaronq · Answer

plug it into the formula?

$log\;\gamma=0.5Z^+_0Z^-_0.. etc$

it's kinda weird though because they don't give you the negative  counter ion

anonymous · Answer

if I were to do this manually  using that given range, how would I approach it?

aaronq · Answer

you would calculate the coefficient for several points (ionic strengths) do 3 or 4, then plot these. Activity coefficient on the y axis and ionic strength on the x axis (although you can do on which every way you want)

aaronq · Answer

it's much easier if you do it in excel though

anonymous · Answer

yes, that is where I am having problem.

anonymous · Answer

like that range is between 10^-4 to 1 right?

aaronq · Answer

yep thats the range of "I" they gave

anonymous · Answer

how would I calculte that in excel though?

anonymous · Answer

if I do it manually then can I chose to do something like I= 10^-4,10^-3, 10^-2 and 10^-1?

anonymous · Answer

choose**

aaronq · Answer

yeah thats fine

aaronq · Answer

for excel you need the x data point and the y data point

the x you can just make up: 10^4, 10^3
then for the y you have to use the result from the equation, so you would type up the equation and use the x data points, then fill it. If you're not familiar with excel trying it this way might take you awhile

anonymous · Answer

okay, thank you so much.

aaronq · Answer

no problem, good luck!

anonymous · Answer

thanks :-)