|Here is the phase diagram of salt water, i.e. water (H2O) with some dissolved salt (NaCl).|
|Now let the mixture freeze or
solidify. The fact that this happens at rather low temperatures compared to the
freezing temperature of steel, for example, is completely irrelevant for the
general considerations we are doing here.
You should now be able to draw some conclusion on your own.
|"Ice" means solid and rather pure
H2O with almost no dissolved salt in this case.
Never mind the NaCl end! NaCl · 2 H2O means that you have a rock salt crystal with water molecules as a kind of dissolved impurity (2 H2O molecules occupying the place of one NaCl unit). The key word in this context is "crystal water" - look it up!
|OKI help you. What we see for
low salt concentrations up to 30 % or so, is:
|Now you know why the ice swimming in the oceans is sweet, why salting ice and snow will melt the stuff (provided the temperature is not below the eutectic temperature), how much salt you need to thaw a given amount of ice or snow, and how much salt you can dissolve in some amount of water.|
6.2.2 Solidification and the Art of Casting
Early Pyrotechnolgy - 2. First Technical Uses
10.4. Crucible Steel 10.4.1 The Making of Crucible Steel in Antiquity
© H. Föll (Iron, Steel and Swords script)