FMF - Friends of Minerals Forum, discussion and message board

[Tom Mazanec]

As I read my field guides on minerals, I keep seeing "effervesces in cold/warm/hot hydrochloric acid".
What are the dividing lines between these temperature ranges?

[Pete Richards]

I don't believe there are any hard and fast dividing lines between these temperatures. I would think of cold as being room temperature, warm as being like a bath, and hot as being near boiling. So perhaps 68° F, 95° F, and 180° F, But it is a continuum. If you put a specimen in cold acid and nothing happens, you can then warm it up with a thermometer in place and see if effervescence starts at a particular temperature.

Note that the presence or absence of a reaction also depends on the acid and its concentration. The guides often specify hydrochloric acid and usually mean a dilute solution - and that's another vague statement - but the more advanced textbooks often refer to other acids as well.