Equation for Temperature Derivative of the Activity

If we differentiate Equation (16.39) with respect to temperature at constant molality and pressure, and substitute from Equation (9.57), the result is 

From Equations (16.35), (16.37), and (16.38), we observe that for solute and solvent, is equal to Therefore, we can write Equation (16.40) for either solvent or solute as 

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