Deliquescing salts taking up moisture from the Mars atmosphere: Difference between revisions
Deliquescing salts taking up moisture from the Mars atmosphere (edit)
Revision as of 01:41, 13 December 2018
, 5 years ago→After salt mixtures take up water, they retain it after supercooling, and reduced humidity
Line 66:
However, as you freeze further below that temperature, you may find that the salt continues to remain liquid. The reason for this is that for a salt to come out of solution through nucleation, it has to form a new interface between the crystal surface and the liquid, which requires energy. Once the nucleation starts, then crystallization is rapid, but the nucleation can be delayed often for many hours.
For instance, MgSO<sub>4</sub> has a eutectic of -3.6 °C but through supercooling can remain liquid for an extra -15.5 °C below that. Here is a table of some salts likely to be found on Mars, showing the eutectic temperature for each one (with the molar concentration for the optimal eutectic concentration in brackets) and the amount of supercooling below that temperature that they found with experiments (adapted from table 2 of <ref name="TonerCatling2014"/> - omitted some of the columns). The magensium and calcium perchlorates are from Marion et al, 2010<REF>Marion, G.M., Catling, D.C., Zahnle, K.J. and Claire, M.W., 2010. Modeling aqueous perchlorate chemistries with applications to Mars. Icarus, 207(2), pp.675-685</REF>
{| class="wikitable"
Line 79:
|-
| NaClO<sub>4</sub> || -34.3 °C (9.2 m)|| 11.5
|-
| MgClO<sub>4</sub> || {{convert|204.55|K|C}}|| (3.48 m)||
|-
| MgClO<sub>4</sub> || {{convert|198.55|K|C}}|| (4.20 m)||
|}
| |||