RE: bichromate gum
BTW, this is nothing new (the "same molarity - same speed / contrast"
issue I mean); this was noted in the list before (probably by Katharine, I
don't know who else might have wrote about this)...
13 Temmuz 2008, Pazar, 10:28 am tarihinde, Loris Medici yazmış:
> Indeed. There are two forms of NaDi: anhydrous and dihydrate. My
> calculation was made according to dihydrate -> since that's what you
> "usually" get from the chemical suppliers. Maybe Judy's NaDi was the
> anhydrous form, therefore in her experience NaDi was faster than KDi at
> the same w/v strength.
> Lets re-make the calculation for anhydrous NaDi:
> [KDi Strength] * ( [NaDi m.w.] / [KDi m.w] ) = [equiv. NaDi Strength]
> 10% * ( 262.01 / 294.19 ) = 8.9% (~ 9%)
> So, 8.9-9% NaDi is virtually the same as 10% KDi (or 8.5% NH4Di)...
> Thank you for the remark Alberto.
> 12 Temmuz 2008, Cumartesi, 8:15 am tarihinde, Alberto Novo yazmış:
>> The "reply-to" of Loris' message was set to his personal address instead
>> The List, so I post my reply again
>>> sodium dichromate's (NaDi) molar mass is 298.02g
>> this is for Na2Cr2O7.2H2O.
>> For the anhydrous form, the M.W. is 262.01. In this case the math