Science Buddies: "Ask an Expert"

My son has did the experiment portion of this project. We saturated the boiling water with borax and after about 2 1/2 hours, some crystals began to form. What are the crystals supposed to look like? His look like 5-6 snowflakes stuck together and are very fragile. Even after sitting overnight, when we take the string out of the water, they fall off. We were thinking that these would be somewhat hard crystals. Any ideas on what, if anything went wrong?

I am not a chemist, and have worked with borax only as a cleaning agent, so I had to do a bit of research to answer your question.

Borax crystals are quite soft and colorless to slightly white. It seems the crystals your son grew are fairly typical. They are also fragile, which explains why they easily fall off the string.

There are many things that could affect the quantity of crystals that grew. This might also affect how well they attach themselves to the string. The things that could affect how well they grow include, the temperature of the water they were mixed in, the purity of the water, the concentration of the borax in solution with the water, how quickly the solution cooled to form the crystals, the rate of evaporation of the water in the solution as the crystals were growing, and probably several more.

For your son's science project, he should first state his hypothesis. That is what he expects to happen or observe. Then he should present what he did and what he observed, and how that compares to his hypothesis. This is the "scientific method".

I hope this helps, and that he has had fun!

Thank you for your reply!

We tried the experiment again after doing more online research. I think our initial problem was not adding enough borax. We found that adding 3 Tbsp. per cup of water produced amazing crystals that are very hard and grow on the string well.