Rotating Gold Ring-Disk Study OT Tin(II) in 4.0 Molar Hydrochloric Acid

Cyclic voltammetry at a rotating gold disk electrode showed that Sn(II) in 4.0M HCI is oxidized to Sn(IV), E_1/2= +0.17 V (SCE) at 10^-4A1 Sn(II). Ring-disk experiments showed that Sn(II) is adsorbed on gold at E < +0.2 V, and underpotential deposition of Sn(0) occuss at —0.6 V < E < 0. Bulk deposition of Sn(0) begins at —0.6 V. About 230 μC/cm²of Sn(II) are adsorbed and/or deposited underpotentially as Sn(0) at ~ —0.15 V. About 128 μC/cm²of the Sn(0) deposit is oxidized at —0.15 V to soluble Sn(II) during the anodic scan. Strongly adsorbed Sn(II) (102 μC/cm²) is not removed until the disk potential reaches +0.15 V, where the adsorbed Sn(II) is oxidized to soluble Sn(IV).