I am facing some difficulties during the preparation of density solution of NaCl. During preparation, after some time, tiny thin crystals of salts are forming at a high rate. The temperature was maintained between 90 - 100 degree centigrade.
Tabulated values for the density (ρ) of NaCl aqueous solutions can be retrieved from (e.g.) [1]. I have correlated this data, for its concentration and temperature dependency, by means of the exponential correlation: ρ = A·exp(B·c), with ρ in g/cm3 and c in wt%, i.e., 100·(msalt/msol.)%. Concentrations range from 1 to 26 wt% and temperatures from 0 ºC to 100 ºC. A and B are temperature-dependent parameters that were quadratically correlated with the reciprocal of the absolute temperature, T (K): A = a1·(1/T)2 + a2·(1/T) + a3 and B = b1·(1/T)2 + b2·(1/T) + b3. The temperature dependency parameters were least-squares fitted to the mentioned data as: a1 = -4.805250E+04, a2 = 3.475451E+02, a3 = 3.724003E-01; b1 = 1.034301E+03, b2 = - 6.302323, b3 = 1.643704E-02; written here without dimensions for the sake of simplicity. The maximum correlation (relative) error did not exceeded ±0.1%.
Saturating concentrations, for the temperature range from 0 ºC to 100 ºC, can be retrieved from (e.g.) [2]. For 0 ºC, the saturating concentration would be 25.90 wt%, while for 100 ºC we would have 28.27 wt%; increasing between. Substitution at the above mentioned correlation gives densities, for NaCl saturated aq. sol., of 1.207 g/cm3 at 0ºC and 1.168 at 100 ºC. Reported concentrations are obviously given in terms of anhydrous salt.
References:
[1] R.H. Perry, D.W. Green, J.O. Maloney (Eds.), "Perry's Chemical Engineers’ Handbook", 7th ed., McGraw-Hill, 1997, cf. Table 2-88.
[2] A.N. Campbell, N.O. Smith, Alexander Findlay (original author), "The Phase Rule and its Applications", 9th ed., Dover Publications Inc. (USA), 1951, p. 391.
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