lspitivanje polarizacije na platinskoj elektrodi. I

Ispitivanje polarizacije Pt elektrode izvedeno prema Hicklingovoj metodi, ali mpdificirano na taj naoo, da je ».povratni udarac« uspo.ren, omogucilo je tocnije pracenje tih pojava. Bilo je moguce povezati i snimiti zajedno brze promjene, koje se zbivaju na elektrodi kod naizmjenicne .anodne - katodne polarizacije. Tako zajedno snimljene krivulje upucuju i na opcu analogiju procesa i omogucuju tumacenje pojedinih faza zbog njihove povezanosti u anodnoj i katodnoj polarizaciji

Electrochemical Properties of the Ion-Exchange Membranes Junction. I.

This paper reports the investigation of electrochemical phenomena at an electrolytic junction of a rectifying system with membranes, and the behaviour of such a system when current flows through it in forward direction. After formation of such a junction a potential difference appears as it is to be expected. The nature of this potential difference has been examined. When current flows through the system in forward directdvn two processes take place, which are importa nt for the overall resistance of the system: a cha nge in the resistance of the thin layer of liquid between th~ membranes, and a lowering of the potential difference between the membranes. After the termination of a pulse it takes a certain »t ime ·of relaxation « for the system t o return to its original state, i. e. to establish the original potential difference between the membranes. This »time of relaxation« depends on the l ength of the pulse and the intensity of current use d

Electrochemical Properties of the Ion-Exchange Membranes Junction. II.

Current flow through the membranes rectifying system in the reverse direction depends mostly on the potential difference bui1t up between the membranes. The change of the potentiaJ. difference between membranes dulling the current flow in the reverse direction is signdficantly greaiter than, and of the opposite sign :flrom, that dill the forward direction. The current in the reverse state is higher than expected because of imperfect experimental conditions (impurities in the system) but it is still suff,iciently small compru-ed to the current in -the forward state. Bes.ides, the effect of rectiflicaition is Lower than expected becaruse of the sluggishness of the system during the fast transition from the forward into the reverse state

Electrochemical Properties of the Ion-Exchange Membranes Junction. III

The mechanism of amplificatfon of alternating current in the investigated membranes system is based upon the properties of membrane rectifiers, which represent the essential part of the circuit. An important role in the effect of amplification of a.c. is played by the intrinsic sluggishness\u27 of the r ectifiers, which leads to an excess of current already in the second half-period of the first wave after the switching on of the impulse circuit. This excess of current accumulates and amplification increases reaching finally a constant value, which corresponds to a steady state of the system. The current a mplification factor depends on the frequency of the a.c. u sed in the m ain circuit: the lower the frequency of the current applied, the higher the final value. This final value of the current amplification factor is attained faster if the current applied in the impulse circuit is higher

Polarografsko ispitivanje alkaloida. I

Izvedeno je polarografsko ispitivanje otopina kinidina sa svrhom da se ustanovi priroda vala, koji prethodi katalitickom izlučivanju vodika. Utvrdeno je, da se radi o adsorpcionom valu i izračunata je količina adsorbiranog redukcionog produkta

Aparatura za mjerenje kapaciteta električnog dvosloja kapajuće elektrode

Prikazana je konstrukcija aparature za mjerenja kapaciteta električnog dvosloja kapajuće živine elektrode. Elektroda se polarizira konstantnom strujom, pri čemu se nabija električni dvosloj. Promjene potencijala s vremenom se pojačavaju preko jednostepenog istosmjernog pojačala i registriraju snimajući krivulje koje rezultiraju na zastoru katodnog oscilografa. Dani su primjeri određivanja kapaciteta dvosloja u otopini 0,1 N NaOH

Polarografsko ispitivanje alkaloida. I

Izvedeno je polarografsko ispitivanje otopina kinidina sa svrhom da se ustanovi priroda vala, koji prethodi katalitickom izlučivanju vodika. Utvrdeno je, da se radi o adsorpcionom valu i izračunata je količina adsorbiranog redukcionog produkta