Electrical Conductivity and Frozen Salt Water

A demonstration to show that freezing salt water decreases the conductivity of the solution. For more information including instructions, discussion of concepts, and other demonstrations visit the NKU demonstration database at ChemDemos.nku.edu

Category:

Education

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• frozenwater

[finkako86]

Nice and interesting demo, but the measurement for liquid water doesn't make sense.

When salt is added, the conductivity of purified liquid water rises to from 6 to 300 μS/cm². Next day, the reading of the frozen solution is still said to be 300, but you also mention that the yesterday's reading was actually 8,500 μS/cm².

Apparently the measurement for the first day with salt added eventually rose to about 8,500 μS/cm².

[sieveb1]

@finkako86 ya the reason for the difference is that it was two different solutions. The frozen one was one I made the day before so it would be frozen solid before filming had the high value as I added a significant amount of salt to it. The first solution (not the same solution) is actually very low as I didn't give it much time to dissolve and the probe to get a good reading. I was just trying to show that pure water does not conduct but the addition of the salt allowed the value to rise.

[sieveb1]

@finkako86 (sorry my response was longer than allowed.) So sorry that I was not clearer in the video that it was indeed two different solutions the first one only to show the conductivity rose with the addition of salt and the second frozen one which had a value of about 8,500 μS/cm² then rose to about 9100 μS/cm² upon thawing.

[thewii552]

what the heck is a "digital probe"?