blue bottle prac

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RosalieL
Posts: 131
Joined: 28 Jan 2021, 13:24
Job Title: Lab Assistant
School: MCS
State/Location: NSW

blue bottle prac

Post by RosalieL »

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
RosalieL
Posts: 131
Joined: 28 Jan 2021, 13:24
Job Title: Lab Assistant
School: MCS
State/Location: NSW

Re: blue bottle prac

Post by RosalieL »

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!
mtg
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Joined: 15 Aug 2011, 10:48
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School: NDSC
Suburb: west gippsland
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Re: blue bottle prac

Post by mtg »

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.
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Lyn
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Re: blue bottle prac

Post by Lyn »

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.
RosalieL
Posts: 131
Joined: 28 Jan 2021, 13:24
Job Title: Lab Assistant
School: MCS
State/Location: NSW

Re: blue bottle prac

Post by RosalieL »

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!
mtg
Posts: 414
Joined: 15 Aug 2011, 10:48
Job Title: Lab Tech
School: NDSC
Suburb: west gippsland
State/Location: VIC

Re: blue bottle prac

Post by mtg »

Traffic light is good too
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