No abstract

N. Y. 11210 Solubility (ion-activity) products of potassium picrate (KPi), potassium tetraphenylborate (KBPhi), and triisoamyl-n-butylammonium picrate (TABPi) were determined at 25°C. over the entire range of ethanol-water solvents, and those of triisoamyl-nbutylammonium tetraphenylborate (TAB BPfu), in 40 to 100 weight % ethanol in water. Molar absorptivities of picrate and tetraphenylborate ions were obtained as a function of ethanol-water composition in the visible and ultraviolet regions of the spectrum, respectively. Saturated solutions of the title electrolytes were analyzed quantitatively by spectrophotometry. Mean ionic activity coefficients of the electrolytes in saturated solutions were evaluated from studies of their solubility as a function of ionic strength varied by means of added lithium chloride. At solubilities < 10"3 M, activity coefficients obeyed the limiting Debye-Hückel law.

No abstract

is counterbalanced through a potentiometric circuit made up of the variable resistance, n-, and the potentiometer, «2. Thereafter, only the potential resulting from the unbalancing of the system feeds a recorder, R. A standard source, P, of potential is used to determine with accuracy the absolute value of the balance point on the recorder.Resistance. All resistance measurements of the solution were made with a conductivity bridge of Type LKB 3216B modified as follows: A set of decade-resistance units from 0.001 to 1000 ohms increased the precision of the bridge; a series of decade-capacitor units from 0.01 to 1 µ . was added to expand the Wagner earth circuit; finally an oscilloscope was substituted for the magic eye. Figure 4 shows how the signal coming from the bridge is filtered and amplified at A, rectified and compressed at K, and finally recorded at R.Measurement. The cell is filled with ammonium nitrate solution at a temperature very close to that of the bath in which it will be immersed. At thermal equilibrium a balance point is preselected on the chart of the recorder and tied into the potentiometric circuit (Figure 3). Thereafter, the variations of resistance and temperature of the• solution in the cell are simultaneously registered on one graph by a two-channel recorder.The specific conductances for a 0.1 D KC1 solution reported by Gorbachev (9) were utilized to determine the cell constant which, in the temperature range 25°to 95°C ., was found to be unchanged. RESULTS AND DISCUSSIONBased on the precision of the instruments utilized, the accuracy obtained in the determination of the specific con-ductance of ammonium nitrate solutions is ±0.01% of the values shown in Table I. The absolute values are affected by an error of 0.1%, resulting mainly from the quality of standards used for thermocouple calibration.The behavior of the specific conductance as a function of concentration is similar for all temperatures. The curves show a maximum in the vicinity of 52 weight % NH4N03.Campbell's results (3, 4) have been plotted in a similar manner (broken lines). The maxima found are in very good agreement with the present data (Figure 5).