Basic and Acidic Reactions of Litmus paper?

[Genecks]

What do the reactions of Litmus paper with an acid look like? with a base?

 

I'm guessing it's

 

(organic structure of litmus) + acid ---> red

 

(organic structure of litmus) + base ---> blue

 

I'm looking for molecular structures that describe these processes.

Any suitable molecule for an acid or base would be fine.

[John Cuthber]

Do you know how complicated litmus is?

[Genecks]

Not really.

 

If it's super-complex, that might explain why I didn't see easy reaction descriptions for it.

 

But, if you want, humor me.

 

Otherwise, I'm guessing I should be looking through databases that have maybe 10+ page articles that describe the process?

 

*update*

I'm looking through a database, and I'm not really finding any information about what I want to know.

I'm going to guess that litmus paper is paper with an attached heterogeneous mixture composed of with multiple organic compounds?

 

Truth be, I've been curious about this for a few years.

Edited July 2, 2010 by Genecks

[CharonY]

Litmus is an extract from lichens and contains over 10 different chromophores, if memory serves. Most of the time one uses a synthetic pH indicator, though.

[Genecks]

I made sure I read the Wikipedia article before I made the thread: http://en.wikipedia.org/wiki/Litmus_test

Litmus is a water-soluble mixture of different dyes extracted from lichens, especially Roccella tinctoria. ...The litmus mixture has the CAS number 1393-92-6 and contains 10 to 15 different dyes.

 

I was assuming that perhaps some acid/base reactions occurred to this molecule:

 

[CharonY]

Well, if there is a wiki article about it, I am not sure what your question is. Litmus is actually a polymer consisting of chromophore subunits (at least as far as I recall). Though the basic reaction is of course still protonation/deprotonation.