I think it a good idea any time. People put lots of reliance on equilibrium conditions and assume that concentrations, activities etc. will be those that examination of thermodynamic equilibrium produce. Thermodynamics gives us a means for computing these quantities at equilibrium but gives us no indication how long it takes to reach equilibrium or indeed it it will ever be reached. In most cases analysis of equilibrium conditions is very helpful and this may well be one of those cases but I do have some concerns. If, for example, one made a saturated solution of calcium chloride at one temperature and allowed it to cool it would be supersaturated at the lower temperature. The argument then is that the crystals would grow as the extra CaCl2 comes out of solution and I don't doubt that this is what happens. But think about making rock candy if you ever did that as a kid. It takes some time for the crystals to grow. I don't have data about CaCl2 in this regard but I'd want to be cautious until I did and would therefore take density measurements until I did. Since it's so easy to do that I don't frankly see much appeal in the CaCl2 case (with Ca(OH)2 we don't really have much choice).
All this is probably mooted by the fact that we are not trying to do certifiable quantitative chemistry here but just get an estimate (±10 - 20%?) of how much CaCl2 we are putting in our mash tuns.
All this is probably mooted by the fact that we are not trying to do certifiable quantitative chemistry here but just get an estimate (±10 - 20%?) of how much CaCl2 we are putting in our mash tuns.
