Sciencemadness Discussion Board - Hardened Borax in Beaker

Hardened Borax in Beaker

electrokinetic - 17-3-2017 at 19:12

A colleague borrowed my 2 L beaker and made a borax solution in it for her students. She doesn't remember the concentration she made, but she does say it was nothing but water and Muleteam borax from the supermarket. She let it sit and the stuff just hardened in the bottom, there's about 200 ml of hardened solid white crystal at the bottom. Refilling it with water failed to dissolve it. Pouring 150 ml of 8.6 M NaOH per some website she saw also has failed to do anything. Does anyone have any suggestions for removing this stuff? Thanks for your time.

Tsjerk - 17-3-2017 at 19:21

Try to boil the water, the solubility goes up enormously (1 g/16 ml at room temperature; 1 g/0.6 ml boiling water).

If that doesn't help you could try heating it with an acid, sulfuric acid e.g. to make boric acid which is even more soluble in hot water.

electrokinetic - 17-3-2017 at 20:02

Quote: Originally posted by Tsjerk

Try to boil the water, the solubility goes up enormously (1 g/16 ml at room temperature; 1 g/0.6 ml boiling water).

If that doesn't help you could try heating it with an acid, sulfuric acid e.g. to make boric acid which is even more soluble in hot water.

Thanks, I will try that. If it comes to using the sulfuric acid, what concentration should I use?

Tsjerk - 17-3-2017 at 21:16

A couple of percent sulfuric acid should be enough, you only have to dissolve the parts that touch the glass