Why does adding MgS to water lower its freezing point?
I doubt that adding MgS to water is going to lower the freezing point by much. The reason is that there will be very relatively few particles in solution. Magnesium sulfide will react with water to make H2S(aq) and Mg(OH)2. Magnesium hydroxide is essentially insoluble in water. The Ksp is 1.8 x 10^-11. Some of the H2S will bubble out as a gas. A small fraction of the H2S will dissociate to make H+ and HS-. The species in greatest concentration will be undissociated, aqueous H2S To adequately determine the freezing point depression you will need to determine the concentrations of H2S, H+, HS-, Mg2+ and OH-. And the concentrations will need to be in terms of molality. DeltaT = i x kf x m The easiest way to deal with this is to set i = 1 and compute the combined concentration of what’s in solution as m. =========== Follow up ============ Lor has mentioned the compound splitting apart into ions as if MgS dissociated into Mg2+ and S2- ions. Some compounds might do that, but NOT MgS. Most su
