A study of ionic association in aqueous solutions of bi-bivalent electrolytes by freezing-point measurements

1955 ◽  
Vol 232 (1190) ◽  
pp. 320-336 ◽  
Keyword(s):  
Aqueous Solutions ◽  
Potassium Chloride ◽  
Dissociation Constants ◽  
Freezing Point ◽  
Ionic Association ◽  
Freezing Point Depression ◽  
Physical Status ◽  
Copper Zinc ◽  
Cobalt And Nickel

Measurements of freezing-point depression with a precision of ± 0-0002° C have been made on aqueous solutions of potassium chloride and the sulphates of copper, zinc, magnesium, calcium, cobalt and nickel. The results for the sulphates have been analyzed using the theory of incomplete dissociation in a manner which makes clear the physical status of the dissociation constants obtained, and the relation between the approaches associated with the names of Bjerrum and Davies. The values of the dissociation constants are compared with those obtained by other methods.

The rectal complex of the mealworm Tenebrio molitor , L. (Coleoptera, Tenebrionidae)

1964 ◽  
Vol 248 (748) ◽  
pp. 279-314 ◽  
Keyword(s):  
Relative Humidity ◽  
Potassium Chloride ◽  
Freezing Point ◽  
Physiological Mechanism ◽  
Body Cavity ◽  
The Body ◽  
Malpighian Tubules ◽  
Freezing Point Depression ◽  
Faecal Pellets ◽  
Perinephric Space

The rectal complex of the mealworm is an example of the ‘cryptonephric’ condition, wherein the distal ends of the Malpighian tubules are closely applied to the rectum and enclosed with it in a special chamber, the perinephric space, which is separated from the rest of the body cavity by the perinephric membrane. Wigglesworth has suggested that this arrangement serves to assist in the removal of water from the faeces by the rectal epithelium, but its physiological mechanism has remained virtually unexplored. In the present work the ability of the rectal complex to remove water from the faeces has been quantified and it is shown that the faecal pellets are in equilibrium with an atmosphere of 90 % relative humidity (average) and sometimes of as low as 75 % relative humidity. The concentration of the perinephric fluid is greater than that of the haemolymph (first observed by Saini); when the insect is deprived of water the freezing-point depression of the perinephric fluid may reach 8 °C at the posterior end of the rectal complex, and is mainly due to some nonelectrolyte. The freezing-point depression of the tubular fluid from the perirectal tubules is always very close to that of the perinephric fluid and can be almost completely accounted for as potassium chloride which may reach a concentration of over 2 m . The perinephric membrane is relatively impermeable to water. Water injected into the rectal lumen is quickly absorbed into the perinephric space and eliminated via the tubules. It is suggested that the physiological mechanism of the rectal complex is as follows. In water-deprivation the concentration of the haemolymph rises and this activates the rectal complex. Activation involves the secretion of potassium chloride from the haemolymph into the perirectal tubules (either directly or indirectly) whereby water is passively drawn into the tubules from the perinephric fluid. The concentration of the perinephric fluid is thereby increased and the work required to be done by the rectal epithelium in removing water from the faeces is decreased.

scholarly journals Freezing Point Depression of Polyol-Aqueous Solutions in the High Concentration Range.

1996 ◽  
Vol 2 (1) ◽  
pp. 38-42 ◽  
Author(s):  
Tatsuya URAJI ◽  
Hiroyuki KOHNO ◽  
Hiroshi YOSHIMURA ◽  
Makoto SHIMOYAMADA ◽  
Kenji WATANABE
Keyword(s):  
Aqueous Solutions ◽  
Freezing Point ◽  
Freezing Point Depression ◽  
High Concentration ◽  
High Concentration Range

A spectrophotometric study of ionic association in aqueous solutions

1958 ◽  
Vol 244 (1236) ◽  
pp. 124-139 ◽  
Keyword(s):  
Aqueous Solutions ◽  
Activity Coefficients ◽  
Dissociation Constants ◽  
Spectrophotometric Study ◽  
Potassium Ferricyanide ◽  
Potassium Ferrocyanide ◽  
Lanthanum Chloride ◽  
Ionic Association ◽  
Extinction Coefficients ◽  
Ionic Activity

Measurements are reported of the extinction coefficients of aqueous solutions of potassium ferrocyanide, potassium ferricyanide, thallous perchlorate, thallous sulphate, thallous ferrocyanide and mixtures of lanthanum chloride and potassium ferrocyanide. Observed deviations from Beer’s law in the last three cases have been interpreted in terms of the theory of incomplete dissociation, paying particular attention to assumptions about ionic activity coefficients. The formulae of the associated ions in ferrocyanide solutions have been determined by the method of continuous variations and thermodynamic dissociation constants have been obtained at 25, 35 and 50° C for the TlFe(CN) 3- 6 ion and at 25° C for the LaFe(CN) - 6 ion. These dissociation constants are discussed in terms of Bjerrum’s theory of ionic association.

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