In my chemistry lab, there are these rocks in a container that absorb moisture in the air. We use them for experiments when we have a hygroscopic substance that we want to keep dry. What are these rocks called?

Question

anonymous · Answer

those are silica-gel balls, and depending on what coloring agent is they change color, i think they add cobalt chloride, which is blue when it is dry and turns to purple then pink as it becomes saturated.

anonymous · Answer

oh i googled it and found useful link: http://www.articlesbase.com/science-articles/everything-you-wanted-to-know-about-silica-gel-but-didnt-know-who-to-ask-948267.html

jfraser · Answer

they could also be large crystals of mangesium sulfate, or calcium chloride, both of which absorb water from the surroundings if they are dehydrated first.

jfraser · Answer

they could also be large crystals of mangesium sulfate, or calcium chloride, both of which absorb water from the surroundings if they are dehydrated first.

anonymous · Answer

They actually do resemble rocks and not like silica gel at all. They have this pink/orange color to them. I suppose they could be crystals. Thanks!