Naked Science Forum

Non Life Sciences => Chemistry => Topic started by: kowalabear on 17/09/2009 18:39:26

Title: Is there a solid substance which changes colour when exposed to the atmosphere?
Post by: kowalabear on 17/09/2009 18:39:26

Ideally at a reasonably consistent rate over a few days!  Thanks.

Title: Is there a solid substance which changes colour when exposed to the atmosphere?
Post by: Eric A. Taylor on 15/04/2010 00:53:33

There are lots of things that react with air to change color. Mostly with the oxygen. Iron goes from a grayish/silver to rust red, aluminum goes from brilliant shiny silver to dull gray.

Chemicals are very good at reacting with each other. The police have things that react with narcotics. I was stopped once and had an empty Ziploc that that had contained powdered donuts. The cop tested the "powdery whiter substance" and discovered it wasn't illegal and sent me on my way.

Title: Is there a solid substance which changes colour when exposed to the atmosphere?
Post by: Geezer on 15/04/2010 03:29:56

Quote from: Eric A. Taylor on 15/04/2010 00:53:33

I was stopped once and had an empty Ziploc that that had contained powdered donuts.

I'm surprised he didn't book you for stealing his lunch. (Woah! I can't believe I just said that. The popo don't appreciate donut jokes.)

Ahem! Yes, aluminium/aluminum is pretty amazing. It is so reactive that it does not react, if you see what I mean.

Title: Is there a solid substance which changes colour when exposed to the atmosphere?
Post by: lightarrow on 15/04/2010 20:01:46

Quote from: kowalabear on 17/09/2009 18:39:26

Ideally at a reasonably consistent rate over a few days!  Thanks.

Never cut an apple?

Title: Is there a solid substance which changes colour when exposed to the atmosphere?
Post by: Eric A. Taylor on 16/04/2010 06:01:56

Quote from: Geezer on 15/04/2010 03:29:56

Quote from: Eric A. Taylor on 15/04/2010 00:53:33

I was stopped once and had an empty Ziploc that that had contained powdered donuts.

I'm surprised he didn't book you for stealing his lunch. (Woah! I can't believe I just said that. The popo don't appreciate donut jokes.)

Ahem! Yes, aluminium/aluminum is pretty amazing. It is so reactive that it does not react, if you see what I mean.

Ever try to weld aluminum? It melts at a sub-luminous temperature (it never gets "red hot" like steel. Further aluminum oxide melts at a much higher temperature. If you have even a very thin layer you heat and heat then  suddenly the surface kind of slumps down and you know you are totally screwed. The metal has melted and dropped out.

Title: Is there a solid substance which changes colour when exposed to the atmosphere?
Post by: Geezer on 16/04/2010 06:18:06

Quote from: Eric A. Taylor on 16/04/2010 06:01:56

Ever try to weld aluminum? It melts at a sub-luminous temperature (it never gets "red hot" like steel. Further aluminum oxide melts at a much higher temperature. If you have even a very thin layer you heat and heat then  suddenly the surface kind of slumps down and you know you are totally screwed. The metal has melted and dropped out.

Yes. I also invented some new swear words in the process.

Title: Is there a solid substance which changes colour when exposed to the atmosphere?
Post by: Eric A. Taylor on 17/04/2010 23:37:25

Quote from: Geezer on 15/04/2010 03:29:56

Quote from: Eric A. Taylor on 15/04/2010 00:53:33

I was stopped once and had an empty Ziploc that that had contained powdered donuts.

I'm surprised he didn't book you for stealing his lunch. (Woah! I can't believe I just said that. The popo don't appreciate donut jokes.)

All the donuts were legally acquired.

Title: Is there a solid substance which changes colour when exposed to the atmosphere?
Post by: Eric A. Taylor on 17/04/2010 23:40:00

Quote from: Geezer on 16/04/2010 06:18:06

Quote from: Eric A. Taylor on 16/04/2010 06:01:56

Ever try to weld aluminum? It melts at a sub-luminous temperature (it never gets "red hot" like steel. Further aluminum oxide melts at a much higher temperature. If you have even a very thin layer you heat and heat then  suddenly the surface kind of slumps down and you know you are totally screwed. The metal has melted and dropped out.

Yes. I also invented some new swear words in the process.

You cannot claim to have invented anything if it was used before.