Question

What is the activity coefficient for each ion at the given ionic strength? Click here for an activity coefficient table.

Answer 1

This problem involves looking at a table given the species, their charge and their ionic strenght. You can find the table of the activity coefficient on the web by just typing "activity coefficient table".

We can sketch the whole problem in one single table for more clarity:

Species	Charge	Ionic strenght	Activity coefficient
HPO42-	-2	0.01M	0.660
Y3+	+3	0.005M	0.54
Pr3+	+3	0.1M	0.18
(CH3CH2)3NH+	+1	0.01M	0.904

Answer 2

You can find the answer by applying the next equation:

$log\gamma = \frac{-0.51*z^{2}*\sqrt{\mu }}{1+\left ( \alpha \sqrt{\mu }/305 \right )}$

alpha is the size of ion (from table)

Miu is the ionic strenght (given)

z is the charge (given)

Applying this equation for every compound I get.

I + (α 305 Miu sqrt alfa log activity co activity co 400 -0.18034783 0.660164511 miu -2 40.01 0.1 hpo4-2 9 0.005 0.07071068 900 0.268531680.538850537 Y3 0.1 0.31622777 900 -0.75084687 0.177481516 Pr3 1 0.01 0.1 500 -0.04381690.904030533 CH3 CH3 NH+