Search this site

Embedded Files

NaBH4 Reduction

Home
Introduction
Reaction
TLC Analysis
Purification
Melting Point Analysis
Clean Up
Conclusion

NaBH4 Reduction

Home
Introduction
Reaction
TLC Analysis
Purification
Melting Point Analysis
Clean Up
Conclusion
More

Purification

Oh no! Your crystals dissolved. You'll need to cool your mixture down again.

The video shows the bottom of a graduated test tube that has a moderate portion of white substance in the bottom and clinging to the walls. A small amount of clear liquid is added, which dissolves some of the substance off of the sides of the test tube and washes it into the bottom. As the mixture settles, we see that the liquid appears to be bubbling as though heated to boiling, which churns and dissolves the white substance even further. Next a boiling stick is inserted and used to stir the mixture, with dissolves any remaining white substance. In the next shot, we see the graduated test tube is clamped in place in a sand bath. The mixture is now boiling rapidly, with bubbles rushing up past the 1.5 mL marking. Also in the sand bath is a metal temperature probe and another graduated test tube labeled “W,” filled with a large volume of clear liquid and a boiling stick. Next we see the graduated test tube cooling back down to room temperature while clamped in midair. It contains a mostly clearly solution up to the 2 mL marking, with a capping layer of white foamy substance extending past the 3 mL marking. Some small white particles are visible in the clear solution, especially around the boiling stick. In the next shot, we see that the foamy layer has extended farther down into the tube and the solution has become more clouded as the white particles grow. The third and fourth shots of the cooling process show show progressively cloudier mixtures, with even larger crystals around the boiling stick. Finally, we see the graduated cylinder inserted in a large plastic tub filled with ice, and then removed again after some time. The appearance of the contents of the tube are largely the same, although fogged somewhat by the condensation of water on the outside of the tube.

Try filtering and washing again.

© UC Berkeley

Report abuse

Page details

Page updated

Report abuse