Ferroxyl agar....brain freeze moment

[linotas]

So I'm making up the ferroxyl agar for the corrosion prac and it needs 10% alcoholic phenolphthaleine indicator solution. Is that a 10% phenolphthalein solution or 10% ethanol added to a normal 1-2% phenolphthaleine indicator solution?

[Labbie]

Ferroxyl Gel, or agar. 7.5g agar, 500ml distilled water, 10ml 0.1M Phenolphthaiein or 1%, 75ml Potassium Ferricyanide III 0.1M, 5ml Sodium Chloride Saturated.

Boil water & agar, remove from heat, when cool to about 30c add phenolphthalein, Potassium Ferricyandie, then Sodium Chloride, a few drops of KOH turns the gel pink, HCL will bring it back to clear.

Do hope this helps you.

[linotas]

Thanks Sue, We have a slightly different recipe but essentially the same. I went with the 10% solution and have already done a test plate and it works really well Last year it didn't so both myself and the teacher are very pleased.