[brnlow]

I guess its been too many years, but I just don't get how to interconvert molarity/normality of solutions that don't involve sodium hydroxide or common acids.

Here is the problem, I am following a protocol for spectrophotometric determination of dissolved ozone.

O₃ + 2KI + H₂O <-> I₂ +O₂ + 2KOH
I₂ + I^- -> I₃^-

determine [I₃^-] at 352 nm

My standard curve is generated using dilutions of a stock iodine solution (.01 N).  When I ordered the iodine solution I assumed the certificate of analysis would tell me ppm I₂.  All it tells me is that the solution is .01 +/- .0005 N. 

I am comfortable with M and ppm, but not N, how do I convert 0.01 N to either M or ppm?

Much appreciated

[AWK]

0.01 N of I2 = 0.005 M of I2

[brnlow]

Thank you

Is N of I2 twice the M because

I2 + 2 e-  -> 2 I-   ?

Been so long....

[AWK]

Equivalent of I2 is an amount of I2 per one mole of exchanged electrons (ie per 1 mole of iodine atoms in this case). Normality is a number of equivalents per 1 liter of solution