Department of Energy Argonne National Laboratory Office of Science NEWTON's Homepage NEWTON's Homepage
NEWTON, Ask A Scientist!
NEWTON Home Page NEWTON Teachers Visit Our Archives Ask A Question How To Ask A Question Question of the Week Our Expert Scientists Volunteer at NEWTON! Frequently Asked Questions Referencing NEWTON About NEWTON About Ask A Scientist Education At Argonne Salt, Crystals, and Bluing
Name: Pat G.
Status: educator
Age: 50s
Location: N/A
Country: N/A
Date: Tuesday, March 18, 2003


Question:
Hi, I have gone through you archives and found things on salt crystals. But, my questions is we made salt crystals using salt, bluing and ammonia,what part does the bluing play in the beautiful crystal formation that forms on a sponge shaped like a tree. Second, I understand why the crystal forms in general, salt being cube shaped etc. But why the fine, soft, feathery formations. Ammonia, does this facilitate the formation or become part of the formation. Bluing, what is it really? Couldn't get crystals to form with Epsom salt, at least not through the sponge, why?


Replies:
Pat,

There is a bit more to growing colored crystals than is apparent at first glance. Pure substances like salt and Epsom salts have a preferred arrangement of their sub-units. Dyes and other additives interfere with (and sometimes distort ) the preferred arrangement. Thus, what should have been cubic is sometimes shaped differently that what one might observe with the unadulterated material.

Also, what one gets in a crystal growing experiment sometimes depends on the substrate on which the crystals grow. The capillarity of a sponge could lead to results different from that observed if the pure solution was simply allowed to evaporate from a covered petri dish.

Bluing is an organic dye whose structure is very different from the structure of the crystals you are trying to grow.

Ammonia is a gas that is not likely to become incorporated within the crystal. Nevertheless, an ammonia solution could change the pH of the growing medium and thereby have an effect depending on the substance being crystallized.

Regards,
ProfHoff 617



Click here to return to the Chemistry Archives

NEWTON is an electronic community for Science, Math, and Computer Science K-12 Educators, sponsored and operated by Argonne National Laboratory's Educational Programs, Andrew Skipor, Ph.D., Head of Educational Programs.

For assistance with NEWTON contact a System Operator (help@newton.dep.anl.gov), or at Argonne's Educational Programs

NEWTON AND ASK A SCIENTIST
Educational Programs
Building 360
9700 S. Cass Ave.
Argonne, Illinois
60439-4845, USA
Update: June 2012
Weclome To Newton

Argonne National Laboratory