phosphoric acid and methyl violet

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RosalieL
Posts: 615
Joined: 28 Jan 2021, 13:24
Job Title: Lab Assistant
School: MCS
State/Location: NSW

phosphoric acid and methyl violet

Post by RosalieL »

Is rustbuster from bunnings a suitable substitute for phosphoric acid? The description online just says it is phosphoric acid but I can't see if there are other additives.

Also, is there a substitute for methyl violet?

The prac is to show the effect of temperature on equilibrium yields and these are the two chemicals involved and I have neither.

I'm also open to alternatives to this prac using things I should already have!
mtg
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Re: phosphoric acid and methyl violet

Post by mtg »

There is 2 more parts to this prac. per student: 5 x 10-4M Fe(SCN)2+ solutions. and 2 x stoppered test tubes containing an NO2/N2O4 mixture. It's in my old Heinemann Chemistry TWO teachers resource book. We aren't running yr 12 chem atm so I don't have the current prac book. I remember it worked well. I did use methyl violet and phosphoric acid. You can google the SDS for Bunnings rustbuster which should give you % of acid. Crystal violet, (Gentian violet) might work I think they are the same thing. Look up the recipe as it is often used as a stain and you want a different make up.
bigmack
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Re: phosphoric acid and methyl violet

Post by bigmack »

Doesn't look good
Rustbuster.png
RANEX RUST BUSTER.pdf
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RosalieL
Posts: 615
Joined: 28 Jan 2021, 13:24
Job Title: Lab Assistant
School: MCS
State/Location: NSW

Re: phosphoric acid and methyl violet

Post by RosalieL »

I've just ordered them from westlab and hopefully they arrive in time for the lesson...
Marama T
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Re: phosphoric acid and methyl violet

Post by Marama T »

Good luck!
bigmack
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Re: phosphoric acid and methyl violet

Post by bigmack »

mtg wrote: 29 Oct 2024, 15:05 and 2 x stoppered test tubes containing an NO2/N2O4 mixture.
Is that the one where the tubes are placed in different temperatures , Fridge , Freezer and Room temp and the gas goes from Brown to almost clear ?

If so be careful .

At my old school we were lucky enough to have had sealed glass tubes of NO2
I remember doing a casual week at another School and having to make sealed Test tubes of it . Made it in Fume hood by dissolving pieces of Copper in Nitric Acid .
Collecting the gas is dangerous . It does nasty stuff to human flesh . I remember not having a stopper so stuck my thumb over end of Test tube . Had a nasty brown flesh wound in thumb for about Three weeks . Hate to imagine breathing that gas …. It’s nasty .

Be careful …. Think through the procedure if you need to make that stuff so you are prepared.
Merilyn1
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Re: phosphoric acid and methyl violet

Post by Merilyn1 »

Also be concerned if the glass tubing were to break.
My HT would not allow it at all. I was very thankful of that!
mtg
Posts: 532
Joined: 15 Aug 2011, 10:48
Job Title: Lab Tech
School: NDSC
Suburb: west gippsland
State/Location: VIC

Re: phosphoric acid and methyl violet

Post by mtg »

To get the NO2 I use a quick fit set up and put the tubing up through a beehive in a trough of water, I have the test tubes ready and wear full PPE and do it in the fume hood. Sometimes I used a gas jar and for another prac, gas syringes.
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