The mean activity coefficient g± of K2SO4 is defined by the equation:
where nw is the amount of water, ns is the amount of salt and n is the number of ions resulting from dissociating 1 mol of salt.
Activity coefficients
| The figure to the right shows the mean ionic activity coefficient of potassium sulfate at 10°C, calculated with the Extended UNIQUAC model. The mean activity coefficient g± of K2SO4 is defined by the equation:
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| The osmotic coefficient is a measure for the activity of water in a solution. The osmotic coefficient is defined by the equation
where nw is the amount of water, ns is the amount of salt and n is the number of ions resulting from dissociating 1 mol of salt. | |
Thermal properties
| The heat of dilution (from molality m) to infinite dilution is the enthalpy change per mol salt when a solution of molality m is diluted to infinite dilution. The heat of dilution to infinite dilution is the excess enthalpy relative to the infinitely diluted solution. |  |
| >The (integral) heat of solution is the enthalpy change per mol salt when an amount of crystalline salt is dissolved in pure water. The heat of solution is dependent on the concentration of the resulting solution. The heat of solution is the excess enthalpy relative to pure water and the pure electrolyte in its standard state. |  |
| The apparent molal heat capacity of a salt is the heat capacity of a solution of one mol of the salt minus the heat capacity of the corresponding amount of pure water. The defining equation for the apparent molal heat capacity (
Cp is the heat capacity of the solution. nw is the amount of water, ns the amount of salt and |  |
) is:
is the heat capacity of pure water