Titer determination in potentiometry - Metrohm

Application Bulletin 206/4 eTiter determination in potentiometryPage 3/4Table. 2:Precipitation titrations (argentometry)Redox titrations (cerimetry, iodometry, permanganometry, ferrometry, Karl Fischer titration)Titrant Titrimetric standard Electrode RemarksSilver nitrate AgNO 3Lanthanum nitrateLa(NO 3 ) 3Cerium(IV) in H 2 SO 4 orHClO 4Sodium chloride NaCl(110 °C)Sodium fluoride NaF(110 °C)Arsenic trioxide As 2 O 3(105 °C)Iodine solution KI 3 Arsenic trioxide As 2 O 3(105 °C)Potassium permanganateKMnO 4Sodium thiosulfateNa 2 S 2 O 3Iron(II) solution(NH 4 ) 2 Fe(SO 4 ) 2Sodium oxalateNa 2 C 2 O 4(105 °C)Potassium hydrogendiiodate KH(IO 3 ) 2(100 °C)Potassium dichromateK 2 Cr 2 O 7(105 °C)6.0450.100 combinedAg ring electrode (referenceelectrolyte: KNO 3saturated) or6.0430.100 Ag Titrode6.0502.150 fluoride ISE;6.0726.107 referenceelectrode (filled withc(KCl) = 3 mol/L)6.0451.100 combined Ptring electrode or6.0431.100 Pt Titrode6.0451.100 combined Ptring electrode or6.0431.100 Pt Titrode6.0451.100 combined Ptring electrode or6.0452.100 combinedAu ring electrode6.0451.100 combined Ptring electrode or6.0431.100 Pt Titrode6.0452.100 combinedAu ring electrodeSodium nitrite NaNO 2 Sulfanilic acid 6.0452.100 combinedAu ring electrodeKarl Fischer reagentSodium tartrate dihydrateC 4 H 4 Na 2 O 6 x2 H 2 O orwater standards inampoules (Riedel-deHaën)6.0338.100 polarizeddouble Pt electrodeDissolve NaCl in 40 mL water, thenadd 2 mL c(HNO 3 ) = 2 mol/L and possibly2 mL 0.2% polyvinyl alcohol solution.(Dissolve polyvinyl alcohol (Merck No.114266) in warm water.)Dissolve NaF in 50 mL water, add10 mL acetate buffer pH = 6.0 andtitrate slowly (see also Metrohm ABNo. 82).Dissolve As 2 O 3 in 10 mL c(NaOH) =1 mol/L, then add 6 mL c(H 2 SO 4 ) =1 mol/L and 2 g NaHCO 3 (see alsoMetrohm AB No. 52).Dissolve As 2 O 3 in 10 mL c(NaOH) =1 mol/L, then add 6 mL c(H 2 SO 4 ) =1 mol/L and 2 g NaHCO 3 .Dissolve Na 2 C 2 O 4 in 40 mL water, thenadd 5 mL concentrated H 2 SO 4 and 1 gMnSO 4 .Stock solution: Dissolve KH(IO 3 ) 2 inwater and make up to 100 mL; use10 mL of this solution, dilute with40 mL water, then add 1 g KI and 4 mLc(HCl) = 1 mol/L.Dissolve K 2 Cr 2 O 7 in 40 mL water, thenadd 3 mL concentrated H 2 SO 4 .Dissolve sulfanilic acid in 50 mL water,add 30 mL w(HBr) = 20% and titrateimmediately using the MET mode(0.10 mL, 25 s).Fill methanol or KF solvent into thetitration vessel and condition. As soonas a steady drift is attained, add thestandard and titrate with the KF reagent.The titer is specified in mg H 2 O / mLKF reagent (documentation availablefrom Riedel-de Haën or Merck).The indicated electrodes are meant as a suggestion. It is often also possible to use other electrodes or electrodesystems.