- #1
Russel Sprout
Hi,
I have a hand warmer a plastic packet filled with Na(C2H3O2)-3H2O and a
small metal disk which is stressed and will produce a click if squeezed
correctly. Once clicked the liquid will crystallize and the heat of fusion
provides the hand warming. I've been asked by my children how it works. As
they are inquisitive children, one answer leads to another question. I've
now come to the point where I cannot supply the answer and neither, it
appears, can Google. The question is this - how does the shock wave from the
click of the metal disk initiate the crystallization? I assume the
Na(C2H3O2)-3H2O is pretty pure and physical nucleation sites are
unavailable, otherwise it would be prone to spontaneous crystallization.
Does the shock wave force a few molecules into the correct alignment
somehow? Any answers would help preseve my credibility.
TIA.
Steve.
I have a hand warmer a plastic packet filled with Na(C2H3O2)-3H2O and a
small metal disk which is stressed and will produce a click if squeezed
correctly. Once clicked the liquid will crystallize and the heat of fusion
provides the hand warming. I've been asked by my children how it works. As
they are inquisitive children, one answer leads to another question. I've
now come to the point where I cannot supply the answer and neither, it
appears, can Google. The question is this - how does the shock wave from the
click of the metal disk initiate the crystallization? I assume the
Na(C2H3O2)-3H2O is pretty pure and physical nucleation sites are
unavailable, otherwise it would be prone to spontaneous crystallization.
Does the shock wave force a few molecules into the correct alignment
somehow? Any answers would help preseve my credibility.
TIA.
Steve.