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)... Regards, Loris. 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. > > Regards, > Loris. > > > 12 Temmuz 2008, Cumartesi, 8:15 am tarihinde, Alberto Novo yazmış: >> The "reply-to" of Loris' message was set to his personal address instead >> of >> 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 >> changes >> accordingly. >> >> Alberto
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