Science Buddies: "Ask an Expert"

My 7-year old daughter did the rock candy project with my help. On Day 1, the day we made the sugar solution, within a few hours after we set aside the 2 jars for observation, we saw a huge blob of sugar in both the seeded and non seeded jars. Today is Day 2 and we can not see the screws at all in both jars as they are totally covered by the huge chunk of sugar. Did something go wrong? The chunks of sugar in both jars look as if we just poured 2 cups of sugar in each jar!

As our jar size was 3/4L, so we used 2 cups of water and 4 cups of sugar. We dissolved the sugar in the pot and my daughter managed to add 4 tbsp of sugar gradually before the solution became totally saturated. The saturated solution felt dense when we stirred and looked a bit opaque before we set them aside for observation. Within hours the 2 jars both looked strange - the top layer of both jars look crystallised, then there is a thin layer of clear solution, followed by a thick chunk of sugar looking thing. Please see the attachment.

Hi Koolliang

Welcome to Science Buddies.

I think you are doing this great, but sometimes challenging project:

https://www.sciencebuddies.org/science- ... p005.shtml

It sounds like there may have been a few particles of undissolved sugar or perhaps some dust particles floating in the solutions that provided a nucleus for the sugar molecules to start the crystallization process. It sounds like you did everything right, except the solutions should have been dense, but clear at the beginning of the experiment.

If you want to set this up again, make sure the saturated solution is clear at the beginning of the experiment. Make sure there are no particles of sugar or anything else in the solution. The string with the sugar particles should be the only surface available to allow the crystallization process to start.

If you don't have time to repeat the experiment, I would like to point out that as a science project, the experiment is complete. Your daughter did the experiment and obtained results, but just not the expected results. Explaining the actual results would make an interesting discussion section.

I hope this helps. Let us know if you have any other questions.


Donna