The entropy change for dissolving salt in water is positive. This is because the salt dissociates into ions when it dissolves, and these ions can move around more freely than the salt molecules could. The increased freedom of movement of the ions leads to an increase in entropy.

The entropy change for dissolving salt in water can be calculated using the following equation:

$$\Delta S = nR\ln(\frac{V_2}{V_1})$$

where:

* $\Delta S$ is the entropy change in J/K

* $n$ is the number of moles of salt dissolved

* $R$ is the ideal gas constant (8.314 J/mol K)

* $V_2$ is the volume of the solution in L

* $V_1$ is the volume of the water before the salt was dissolved in L

For example, if 1 mole of salt is dissolved in 1 L of water, the entropy change would be:

$$\Delta S = (1 \text{ mol})(8.314 \text{ J/mol K})\ln(\frac{2 \text{ L}}{1 \text{ L}}) = 5.76 \text{ J/K}$$

This positive value of $\Delta S$ indicates that the entropy of the system increases when salt is dissolved in water.