Australia's Science Forum

Hi all,
I made a mistake while in a rush when checking we had the ingredients needed for blue bottles and thought I could find everything. I can not find KOH anywhere! Is there a substitute that will work? I need it for after lunch today so don't have time to source it unless I can buy it at a chemist.
Thanks!
Rosalie

My teacher is very understanding and it is for a year 6 class science demo so we're going with an acid/base rainbow in a measuring cylinder instead. Should be fun!

Blue Bottle Prac:- For future reference.
Half fill a 1 litre flask with water and add 10g of sodium hydroxide (or dilute 125ml of 2M NaOH to 500ml)
then add 10g glucose and up to 1 ml of a 1% solution of methylene blue. Stopper the flask and swirl to dissolve contents. I have the equations to explain the reactions if anyone wants it. I also find the methylene blue aqueous soln works better but ethanol soln works ok but sometimes you see a blue ring at the top.

Found this yesterday arvo. The same as mtg's recipe.
To a 1 litre flask add
10g sodium hydroxide
10g glucose powder
1ml methylene blue solution (1%)
500ml water
Cap with tightly fitting stopper
Shake the flask vigorously.

I will try the diluting of 2M NaOH and see how well that works. It's always useful to try other methods of doing demonstrations.

Thank you! I though sodium hydroxide might have been ok but google didn't help and I didn't have time to play and test it myself. The acid/base rainbow was impressive enough though!

Traffic light is good too