[kelly]

I am trying to scale the production of solutions I make in a lab.  We would like to produce 5-20L volumes of various buffer in an accurate and expeditious fashion.  Is there a calculation I can use to determine the final weight of water I need to add to powdered reagents to reach a final volume?

Using Sodium Chloride as an example.  If I was to make 1L of a 1M solution I would weigh out 58.44g of NaCl and then bring the final volume of my water up to 1L.  Knowing water weighs 1g/mL how could I QS by weight and account for the NaCl...i don't suppose it is simply additive?

[Borek]

Masses are simply additive, volumes are not.

In general such calculations require knowledge of the density of the final solution. For NaCl it is not a problem, as these are tabelarized. My CASC (concentration calculator, see signature) does such calculations, but only for solutions for which it either has built in density table or for which you can supply density table on your own.