Dump a couple of Tbsp of sugar into a quart or two jar of tepid water. Don't stir. 𝜇wave a couple minutes, hot but not boiling. Let it sit. Experimental claim: The total dissolved sugar is not an increasing function of time, even though a couple of Tbsp is << enough to saturate even cold water. —rwg
The obvious question, for me, is how are you measuring this process? I imagine that you could extract a cc of solution each minute, then evaporate them and weigh the amount of sugar in each. But I think you're probably not doing that, but rather relying on some kind of visual measure. What is the observed dynamic? Does it dissolve for a while until the concentration hits a plateau, and then sugar starts to precipitate out? On Wed, Mar 20, 2019 at 1:57 PM Bill Gosper <billgosper@gmail.com> wrote:
Dump a couple of Tbsp of sugar into a quart or two jar of tepid water. Don't stir. 𝜇wave a couple minutes, hot but not boiling. Let it sit. Experimental claim: The total dissolved sugar is not an increasing function of time, even though a couple of Tbsp is << enough to saturate even cold water. —rwg _______________________________________________ math-fun mailing list math-fun@mailman.xmission.com https://mailman.xmission.com/cgi-bin/mailman/listinfo/math-fun
The solubility of sucrose in water increases roughly linearly by about 35% from 0C to 100C. Dissolution of sucrose in water is endothermic. Sugar water is denser than plain water. In light of these facts, I don't think the experimental result is particularly surprising, but for how long did you run this experiment, and how accurate are your measurements? On 20-Mar-19 13:57, Bill Gosper wrote:
Dump a couple of Tbsp of sugar into a quart or two jar of tepid water. Don't stir. 𝜇wave a couple minutes, hot but not boiling. Let it sit. Experimental claim: The total dissolved sugar is not an increasing function of time, even though a couple of Tbsp is << enough to saturate even cold water. —rwg _______________________________________________ math-fun mailing list math-fun@mailman.xmission.com https://mailman.xmission.com/cgi-bin/mailman/listinfo/math-fun
Even given the endothermy of solution, I still find the stated facts surprising. As long as the solubility exceeds the actual concentration, we should see sugar going into solution rather than coming out. If that process reduces the temperature, it won't be enough to reverse the direction of the process, because (we are told) there is much less sugar present than will saturate even a cold solution. On Wed, Mar 20, 2019 at 3:34 PM Mike Speciner <ms@alum.mit.edu> wrote:
The solubility of sucrose in water increases roughly linearly by about 35% from 0C to 100C. Dissolution of sucrose in water is endothermic. Sugar water is denser than plain water.
In light of these facts, I don't think the experimental result is particularly surprising, but for how long did you run this experiment, and how accurate are your measurements?
On 20-Mar-19 13:57, Bill Gosper wrote:
Dump a couple of Tbsp of sugar into a quart or two jar of tepid water. Don't stir. 𝜇wave a couple minutes, hot but not boiling. Let it sit. Experimental claim: The total dissolved sugar is not an increasing function of time, even though a couple of Tbsp is << enough to saturate even cold water. —rwg _______________________________________________ math-fun mailing list math-fun@mailman.xmission.com https://mailman.xmission.com/cgi-bin/mailman/listinfo/math-fun
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A similar phenomenon is observed with salt solution: https://en.wikipedia.org/wiki/Brine_pool Brent On 3/20/2019 1:03 PM, Allan Wechsler wrote:
Even given the endothermy of solution, I still find the stated facts surprising. As long as the solubility exceeds the actual concentration, we should see sugar going into solution rather than coming out. If that process reduces the temperature, it won't be enough to reverse the direction of the process, because (we are told) there is much less sugar present than will saturate even a cold solution.
On Wed, Mar 20, 2019 at 3:34 PM Mike Speciner <ms@alum.mit.edu> wrote:
The solubility of sucrose in water increases roughly linearly by about 35% from 0C to 100C. Dissolution of sucrose in water is endothermic. Sugar water is denser than plain water.
In light of these facts, I don't think the experimental result is particularly surprising, but for how long did you run this experiment, and how accurate are your measurements?
On 20-Mar-19 13:57, Bill Gosper wrote:
Dump a couple of Tbsp of sugar into a quart or two jar of tepid water. Don't stir. 𝜇wave a couple minutes, hot but not boiling. Let it sit. Experimental claim: The total dissolved sugar is not an increasing function of time, even though a couple of Tbsp is << enough to saturate even cold water. —rwg _______________________________________________ math-fun mailing list math-fun@mailman.xmission.com https://mailman.xmission.com/cgi-bin/mailman/listinfo/math-fun
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participants (5)
-
Allan Wechsler -
Bill Gosper -
Brent Meeker -
Hilarie Orman -
Mike Speciner