No. 90/2 e Application Bulletin - Metrohm

Application Bulletin No. 90/2 ePotentiometric analysis of tin plating baths Page 32. Free fluoroboric acid or free sulfuric acidReagents:• c(NaOH) = 1 mol/L• Sodium sulfate p.a.Analysis:Dilute 10.0 mL bath sample to approx. 50 mL with dist. H 2 O in a beaker. While stirringdissolve approx. 5 g Na 2 SO 4 and titrate afterwards with c(NaOH) = 1 mol/Lagainst the comb. pH glass electrode. The flat potential jump at pH = approx. 3.2 isevaluated.Calculations:1 mL c(NaOH) = 1 mol/L = 87.81 mg HBF 4 or 49.037 mg H 2 SO 4g/L HBF 4 = EP1 x C01 / C00g/L H 2 SO 4 = EP1 x C02 / C00C00 = Sample size in mL original sample (10)C01 = 87.81C02 = 49.037Figures:'fr751 GPD Titrino 05268 751.0011date 2000-06-06 time 08:23 3pH(init) 1.82 DET pH AB90 SO4smpl size 5.0 mlEP1+ 9.932 ml 3.33H2SO497.41 g/l#EP's not correspondingstop V reached------------121110987pH65432AB90 H2SO4EP10.0 2.5 5.0 7.5 10.0 12.5 15.0V [ml]Fig. 3 Titration curve free sulfuric acid3. Chloride determination in acidic tin bathsReagents:• c(AgNO 3 ) = 0.1 mol/L• w(HNO 3 ) = 65%

Application Bulletin No. 90/2 ePotentiometric analysis of tin plating baths Page 4Analysis:Pipet 5.0 mL bath solution into a beaker and dilute to approx. 50 mL with dist. H 2 O.Add 2 mL HNO 3 and titrate with c(AgNO 3 ) = 0.1 mol/L against the Ag Titrode(Ag 2 S-coating).Calculations:1 mL c(AgNO 3 ) = 0.1 mol/L = 3.5453 mg Chlorideg/L Chloride = EP1 x C01 / C00C00 = sample size in mL original bath (5)C01 = 3.5453Figures:'fr751 GPD Titrino 05268 751.0011date 2000-06-06 time 09:02 5U(init) 236 mV DET U AB90 ClEP1 3.473 ml 97 mVChlorid 12.31 g/lstop V reached============250AB90 Cl200150100EP1U [mV]500-500.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0V[ml]Fig. 4 Titration curve chloride determination4. Free hydroxide and carbonate in alkaline bathsReagents:• c(HCl) = 1 mol/L• w(BaCl 2 ) = 25%Analysis:Add 50 mL BaCl 2 to 10.0 mL bath sample in a wide-necked Erlenmeyer flask andboil for a short time. Allow to cool and slowly titrate the still warm solution withc(HCl) = 1 mol/L against the comb. pH glass electrode.Calculations:Two endpoints are obtained. The consumption up to EP1 corresponds to NaOH,between EP1 and EP2 to tin and between EP2 and EP3 to carbonate.1 mL c(HCl) = 1 mol/L = 40.0 mg NaOH or 106.0 mg Na 2 CO 3g/L NaOH = EP1 x C01 / C00g/L Na 2 CO 3 = (EP3 - EP2) x C02 / C00C00 = Sample size in mL original sample (10)C01 = 40C02 =106

Application Bulletin No. 90/2 ePotentiometric analysis of tin plating baths Page 5Figures:'pa751 GPD Titrino 05268 751.0011>stop conditionsstop V:abs.date 2000-06-06 time 10:43 6 stop V20 mlDET UAB90 OH-stop UOFF mVparametersstop EP 9>titration parametersfilling ratemax. ml/minmeas.pt.density 4>statisticsmin.incr. 10.0 µlstatus:OFFdos.ratemax. ml/min >evaluationsignal drift25 mV/minEPC 5equilibr.time34 sEP recognition:allstart V:OFFfix EP1 at UOFF mVpause0 spK/HNP:OFFdos.element: internal D0>preselectionsmeas.input: 1req.ident:OFFtemperature 25.0 °Creq.smpl size:OFFactivate pulse:OFF------------Fig. 5 Parameter report Titrino, free NaOH and carbonate'fr751 GPD Titrino 05268 751.0011date 2000-06-06 time 10:43 6U(init) -277 mV DET U AB90 OHsmplsize 10.0 mlEP1 6.911 ml -77 mVEP2 11.657 ml 196 mVEP3 14.329 ml 286 mVNaOH27.64 g/lNa2CO3 28.32 g/lstop V reached------------400AB90 OH-300EP3200EP2100U [mV] 0-100EP1-200-3000.0 2.5 5.0 7.5 10.0 12.5 15.0 17.5 20.0V [ml]Fig. 6 Titration curve NaOH / (Sn) / Na 2 CO 3Literature• Metrohm Ti Application Note No. T-5, T-21, T-23• Wild,P.W.Moderne Analysen für die GalvanikEugen G. Leuze Verlag, D-88348 Saulgau/Württ. 1972• Jelinek,T.W.Prozessbegleitende Analytik in der GalvanotechnikEugen G. Leuze Verlag, D-88348 Saulgau/Württ. 1999ISBN 3-87-480-135-7