Question

1. Calculate the mean activity coefficient (g_±) for a 2.0 x 10^-3m Na₃PO₄ solution at 25 ºC.
2. Calculate the activity coefficients (g₊ and g_-) of each ion for a 2.0 x 10^-3m Na₃PO₄ solution at 25 ºC AND the value for the mean activity coefficient.

Thanks in advance!!!

Answer 1

The mean ionic activity a± is generally related to the individual ion activities by:

Ionic activities are related to the concentration units of molality, thus the ionic activity is represents as:

Thus according to the Henry law, the Ionic activity is given by the equation:

According the Debye –Huckel , the equation to calculate the mean activity coefficient Ƴ± , for a solution is given by:

The simplified equation is given by:

The mean activity coefficient (a±) for a 2.0 x 10-3m Na3PO4 solution at 25 ºC and the activity coefficients (a+ and a-) of each ion for a 2.0 x 10-3m Na3PO4 solution at 25 ºC is :

Therefore, the mean activity coefficient (a±) for a 2.0 x 10-3m Na3PO4 solution at 25 ºC and the activity coefficients (a+ and a-) of each ion for a 2.0 x 10-3m Na3PO4 solution at 25 ºC is: 0.680 and 0.0031(+0.0031 & -0.0031).