ISSN:
1572-8927
Keywords:
Thermal expansion coefficient
;
specific heat
;
density alcohols
;
t-butanol
;
aqueous solution
;
fluctuation
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Notes:
Abstract A flow method is described for the simultaneous measurement of volumetric specific heat capacities c p v and thermal expansion coefficients α of liquids, using a Picker heat capacity microcalorimeter. the method involves a simple sequence of operations in which the calorimeter unit is used alternately to measure a difference in volumetric specific heats at constant flow rate and temperature, or a flow rate variation resulting from a temperature scan on a flow cell. The precision of the method in α measurements is close to 1% which is comparable to that of current dilatometric methods; the overall time for the combined c p v -α measurement is less than 30 minutes. Typical uses and reliability of the method are illustrated through results for aqueous NaCl solutions, t-BuOH-water mixtures, and α,ω-diols (C2−C5) at 25°C. The α and c p v values in homologous series of normal alkanes, alcohols and diols appear well represented by equations comprising two contributions, one related to the hydrocarbon chain length, the other dependent on the number density of −OH groups. The general trends in these data and comparison with similar results for H2O2 and H2O illustrate the magnitude of the c p v and α ‘anomalies’ in liquid water.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00650517
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