An Electrochemical Carbon Meter for Use in Sodium

Galvanic Cell Studies on Ionic Carbide and Nitride Solutions in Molten Salts

“…The voltage measured at the beginning of the plateau is a function of temperature and of the CaC2 or LisN content in the melt, and its reproducibility was found quite good in the metal layer deposited should be formed by a two-phase system constituted by solid calcium and a liquid Li-Ca alloy. The cell voltage recorded at the beginning of the first plateau hence could be attributed to the existence of cell [I] where the negative electrode is actually constituted by the two-phase system reported above with the following cell reaction Ca (s) § 2C (s) -~ CaC2 (melt) [2] As cs is known to be much more soluble than lithium in molten salts (14), a selective depletion of Ca from the two-phase system is expected and this depletion may be the reason for the formation of the second plateau observed with the carbide cell.…”

Galvanic Cell Studies Involving Calcium Carbide Solutions

“…Upon immersion of the electrode, the current in the external circuit was adjusted such that the theoretical emf calculated according to Eq. [2] and [3] was attained. The cell emf was observed to remain constant.…”

“…and the cell electromotive force to be given by RT EI -" --~ In ac [2] F However, possible problems with the cell were indicated by (i) cell voltages corresponding to carbon activities lower by 0-10% than those from gas equilibration studies using CO/CO2 and CH4/H2 gas mixtures (2), (ii) a need to introduce a nickel gauze partition between the electrodes to prevent carburization, and (iii) the possibility of less than equilibrium voltages because of electronic conduction in the melt as has been discussed for similar cells (3)(4)(5).…”

“…[2] and [3] was attained. External circuitry was assembled consisting of a Hew!ett Packard Model 6206 B d-c power supply operating in the constant current mode, and a standard 10 ohm resistor connected in series with the electrode terminals.…”

Calibration Tests of an Electrochemical Carbon Meter

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Am electrochemical carbon meter for measuring carbon activities has been described previously (1). A key problem in the development of such a device was the selection of a suitable electrolyte.

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