ISSN:
1572-8927
Keywords:
Heat capacity
;
enthalpy of dilution
;
aqueous NaOH
;
aqueous Na2SO4
;
high temperature
;
flow calorimeter
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Notes:
Abstract The apparent molar heat capacity, C p,ϕ, of aqueous NaOH has been measured at temperatures between 50 and 250°C and molalities from 0.05 to 1.5 mol-kg−1. Enthalpies of dilution ΔLϕ were also determined at 99°C and apparent molar relative enthalpies Lϕ were calculated up to 1.9 m. Measurements were performed by means of a flow calorimetric apparatus constructed in our laboratory and standardized for C p,ϕ and ΔLϕ with aqueous Na2SO4 and with the formation of water from its ions, respectively. Characteristics and performance of this calorimeter are described in detail. Pitzer's semiempirical equations are used for the representation of the results and a general fitting of C p,ϕ data is reported using also recent literature values measured between 4 and 55°C. The fitted parameters are finally utilized, through an integration procedure, to derive a general equation to calculate Lϕ at any temperature between 4 and 250°C.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00647315
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