1. The problem statement, all variables and given/known data This question is about entropy of magnetic salts. I got up to the point of finding H1, the final applied field. 3. The attempt at a solution But instead of doing integration I used this: dS = (∂S/∂H)*dH = (M0/4α)(ln 4)2 I removed the negative sign because they wanted decrease in S. I know integration is the sure-fire way to get Sinitial - Sfinal but why is this method wrong? Is it because this method is only an approximation?