Electrochemical affinity, zero

From (37) we see that the electrochemical affinity A of a cell consists of three contributions due to the anodic and cathodic overtensions and to the ohmic drop. If one of the overtensions is zero, as is the case for the reference electrode of the tensiometric cell, and if an RI correction is made, we can write for a single electrode... 

Let us first consider the case where step j concentrates the total electrochemical affinity of the process, making A, ...Aj iy Aj+i,... practically equal to zero. For instance, j could be a charge or discharge step with all approach steps practically at their respective equilibria (see the discussion in section II.2). We then have yjAj = A [see (99)], and from (109) we obtain... 

If the electrochemical affinities of steps other than III can be taken as equal to zero, we have... 

If the approach process e (a)e (a ) were to have a zero electrochemical affinity, we would haveiv - = 0 and according to (201),... 

One of the conventional methods for establishing the existence of active transport is to analyze the effects of metabolic inhibitors. The second is to correlate the level or rate of metabolism with the extent of ion flow or the concentration ratio between the interior and exterior of cells. The third is to measure the current needed in a short-circuited system having similar solutions on each side of the membrane the measured flows contribute to the short-circuited current. Any net flows detected should be due to active transport, since the electrochemical gradients of all ions are zero (Ai// = 0, cD = c,). Experiments indicate that the level of sodium ions within the cells is low in comparison with potassium ions. The generalized force of chemical affinity shows the distance from equilibrium of the /th reaction... 

According to the De Bonder inequality, the product of the affinity of a reaction and its rate is positive or zero. When transposed to electrochemical reactions, the inequality becomes ... 

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