states matter
Nora recently noticed that ice in one’s water or tea appears to ‘melt’ in the cup; this change is particularly noticeable when one is drinking outside on a hot day or starting with very warm tea. What is really happening? To explore this question we recently designed and executed a simple experiment to investigate 2 different states of water: liquid and solid.
Method
300 grams (approximately 500ml) of chopped ice were placed in a beaker which was then placed by the senior researcher on her monkey placemat on the kitchen table. The apparatus was left in place for a 24 hour period during which time the researchers engaged in such scholarly activities as napping, eating bunny crackers, going to school, and playing with toads.
At the end of the 24 hour period the apparatus was again consulted. It was discovered that the ice in the beaker had been entirely replaced with water. The junior researcher encouraged his daughter to feel the water and she reports that it was “not cold!” In fact, the water was 23º C (73.5ºF). The level of this water was approximately 300ml. In figure 2 we see a photograph of the senior researcher painstakingly carrying the apparatus from the table to the kitchen scale.
It was discovered that the water in the beaker (after subtracting the mass of the beaker itself) weighed 301 grams. It was observed that a large amount of water had accumulated on the monkey placemat and on the outside of the beaker itself. The senior researcher surmised that this external water was due to “it’s leaking, daddy!” but no source of leaks could be detected.
The apparatus was moved to a self-contained isolated heat removal and humidity reduction unit (colloquially, “the freezer”) for another 24 hour period and the researchers went to go play the princess game.
When the additional 24 hour period had elapsed, the vessel was found to contain a quantity of ice! A visual inspection revealed no liquid water. The temperature of the material in the beaker now registered at -9ºC (15.8º F). The ice now lacked the airy, cube-like separation of the original ice. Indeed, the top level barely reached 350ml (down from an initial 500ml).
Conclusions
It seems clear that the removal of heat from a vessel of water is highly correlated with the presence of ice in that vessel. Similarly, the addition of heat (even room temperature heat) is highly correlated with the presence of liquid water in that vessel. More rigorous studies will be required to determine the exact transition temperature at which this state change occurs but the researchers are confident in the assessment that our freezer is probably too cold. This last observation is supported by extensive longitudinal data indicating that ice cream from our freezer is “too hard” and “has to sit on the counter for a while before you can scoop it”.
Future work
The experimenters hope to return to the question of the mysterious leak. Where could that water on the monkey placemat have come from? In a possibly related question, what would happen to the water (or to the ice) if it were to be heated to a temperature much higher than room temperature using our localized conductive electrical heat application device (the stove). Much work remains to be done in this area.
June 2nd, 2011 at 12:23 am
Excellent investigation. It sounds to me like you should keep your freezer a tad bit warmer.
June 2nd, 2011 at 11:30 pm
“Daddy, can we try that too?”