Australia's Science Forum

Good Morning Everyone,

I have tried finding a supplier of RESAZURIN with no luck so far. A teacher wants to use it in the "Blue Bottle Experiment".

Other indicators used in the prac are Methylene Blue and Indigo Carmine. Apparently using all three indicators gives colour change from violet, to red, to yellow.

Does anyone know a supplier please? or doesn't anyone use it any more?

Thanks
Rita

Try a Google search it came up with quite a few in Australia. Good luck.

This is the experiment we do - hope this helps.....

I found a supplier ... Sigma Aldrich. $46.41 for 1G or $108.12 for 5G. Might give the purchase a miss and use experiment above.

Thank you

I like the sound of the traffic light demo. The standard blue bottle demo is as follows :-10g of NaOH in a 1 litre flask half filled with water, add 10g glucose and up to 1ml of 1% methylene blue, stopper flask, swirl to dissolve. After a few minutes the solution goes clear, shake it and it goes blue, then clear again, it goes for a day or 2. I think you need water based Methylene blue solution as 1 of mine didn't work. And I add it til it works.
And as I read further I saw the traffic light one which I had never noticed before.
I have the theory of why the blue bottle works if you need it.

We do the traffic light demo here. The method is, add 3g glucose to 250mL distilled water and stir until dissolved, then add 5g NaOH pellets to the mixture. The method says to add 5-10mL 1% indigo carmine but I just add a little bit of powder (not much, just enough to colour the solution yellow). The solution is then stoppered (I put it in a Schott bottle so it can be shaken safely). Hopefully if you shake the bottle once or twice it turns red (oxidising the solution), and more shaking (oxidising) will turn it green. On standing it will go back to red then yellow as the oxygen concentration drops in the bottle due to a reaction with the glucose. I used new glucose this year with better results too