This thread coincides with a previous thread I posted on reddit: http://www.reddit.com/r/chemistry/comments/2g69vt/magnetohydrodynamics_internal_energy_and_system/ I'm trying to solve the following equation: U=TS-PV+HM. The problem is I'm having difficulty solving H delta M. I was told H is the magnetic susceptibility and Wiki suggests that M equals N/V(m): http://en.wikipedia.org/wiki/Magnetization#Definition "Here, M represents magnetization; m is the vector that defines the magnetic moment; V represents volume; and N is the number of magnetic moments in the sample. The quantity N/V is usually written as n, the number density of magnetic moments. The M-field is measured in amperes per meter (A/m) in SI units" But how would this equation work for 1 ml of water in a 0.5 T magnetic field? I'm guessing that for 1 ml of water, this means the number of water molecules x the dipole moment of water divided by 1 ml. 1 ml of water has 3.344 x 1022 molecules with a dipole moment of 1.85 D per molecule. I'm totally confused and in desperate need of assistance. Any help would be greatly appreciated.