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Chemistry Forums for Students => Physical Chemistry Forum => Topic started by: bidwelps on November 01, 2009, 02:29:12 PM

Title: Behavior of solid NaOH dissolving in distilled H2O in different thermal regimes
Post by: bidwelps on November 01, 2009, 02:29:12 PM

While watching friends make soap this afternoon, a question arose.

When dissolving solid NaOH in distilled water in a stainless-steel pot, we place the pot in a sink of cold water to prevent excessive heating due to the exothermic reaction.  When using a different pot which is stainless steel but also has a slab of Cu bonded to the bottom to facilitate even heating, the NaOH tends to not dissolve evenly or really at all, but to change from a pile of pellets to a fused mass forming a coating that pretty much sticks to the bottom of the pot.  The only difference is the thermal conductivity of the two pots' bases, but I fail to come up with a mechanism to explain the different behaviors.

Any suggestions out there?