potassium dichromate

[Rowyrow]

How long does a solution of potassium dichromate last? i'm not talking acidified or anything just plain ole 0.1 M K₂Cr₂O₇ in distilled water? need some on wednesday (my day off) can I make it up tomorrow? will it be ok?

[RosalieM]

I can't see that it would be a problem. I'm pretty sure we keep it for much longer than that, but maybe I'm wrong. If you are really worried (I have done this for other chemicals in the past) you can accurately weigh the amount you need in a small specimen container and supply the distilled water already measured in a flask with a stopper to prevent evaporation so they just have to tip the powder into a beaker and rinse the container with the distilled water and tip into the beaker to make sure they get all the chemical and then tip in the rest of the water and stir until dissolved.

[Lyn]

There will be no problem with the potassium dichromate being made up the day before. However, according to the O H & S Manual Science NTDE 1996 which is still referred to in the current list of chemicals for use in NT schools, potassium dichromate is listed as a category "B" chemical which may only be used by staff and by senior students (Years 11&12) under supervision of *science qualified teaching staff. Don't know if you have a copy of that. If not I may have a copy I can email you. Just let me know.
Lyn.

[Rowyrow]

Hi Lyn,
I would be great if you could email that to me Rowann.Lambert@ntchools.net I have the OH&S manual Science Guidelines 2008 but it doesn't seem to cover which chemicals are allowed for each yr level.
It is being used for yr 11 chemistry so I'm good on that one .
Thnaks!.

[rosaliemb]

Hi Lyn and Rowyrow,
As another NT lab assist. I am uncertain if thse categories of A,B,C,D chemicals still apply, but certainly are a useful guide.
Rosalie (another one)