Question
A solution contains 0.010 M BaCl2. Calculate the molarity of the ions in solution, the ionic strength of the solution, the activity coefficient of the barium ion and its activity. Repeat for the chloride ion.
So I know the molarities for the ions in this compound ((Ba^2+) = 0.01 M and (Cl^-) 0.02). I still don't know what the ionic strength value is. Does it correspond to a specific formula? I tried looking it up, but all I got was various equation with random constants.
So I know the molarities for the ions in this compound ((Ba^2+) = 0.01 M and (Cl^-) 0.02). I still don't know what the ionic strength value is. Does it correspond to a specific formula? I tried looking it up, but all I got was various equation with random constants.
Answers
bobpursley
Ionic Strength= 1/2 (.01)*2+1/2(.02)*1=.01+.01=.02M
Whatttt? Thanks!
Actually, i'm kind of second guessing your post. It doesn't look right to me. I just can't point my finger at it....
bobpursley
https://en.wikipedia.org/wiki/Ionic_strength
Acutally, I did miss it. The charge is squared.
Ionic Strength= 1/2 (.01)*2<b>^2</b>+1/2(.02)*1<b>^2</b>=.02+.01=.03M
Acutally, I did miss it. The charge is squared.
Ionic Strength= 1/2 (.01)*2<b>^2</b>+1/2(.02)*1<b>^2</b>=.02+.01=.03M
How about the activities, how do I solve those?
activity = concn*activity coefficient or for Ba^2+ it is
a = (Ba^2+)*f<sub>x</sub>. Now you want to find f<sub>x</sub>
Look up the Debye-Huckle equation.
a = (Ba^2+)*f<sub>x</sub>. Now you want to find f<sub>x</sub>
Look up the Debye-Huckle equation.
is the concentration from the ionic strength value or from the molarity of ions?
how can i find the activity coefficients?
The activity coefficient is found by the Debvye-Huckel equation. You use ionic strength in that, not concentration. Then concn(molarity)*activity coefficient - activity.