Components:

(1) 1-Methylnaphthalene, C₁₁H₁₀; [90-12-0] NIST WebBook
(2) Sodium chloride, NaCl; [7647-14-5] NIST WebBook
(3) Water, H₂O; [7732-18-5] NIST WebBook

Original Measurements

Schwarz, F. P.; J. Chem. Eng. Data. 1977, 22, 273-7.

Variables:

Ambient temperature: 8.1 - 28.5 °C
Salinity: 30 g(2)/kg sln

Prepared by:

D. Mackay, W.Y. Shiu

Method/Apparatus/Procedure:

The solubility of 1-methylnaphthalene in NaCl solution was determined by fluorescence and UV absorption measurements. In the fluorescence method, saturated solution was prepared by adding excess amount of 1-methylnapthalene to an air-tight 1x1 cm quartz fluorescence cell containing 5 mL salt solution. The cell was rotated at 20 rpm for at least cell 72 hr in a thermostatted water bath and then its fluorescent intensity was measured at 350 and 320 nm. The Spectrofluorimeter employed a ratio-photon counting mode where 1- methylnaphthalene concentration was linearly related to the fluorescence signal. The UV method was used to obtain the absorptivity of 1-methylnaphthalene in ethanol therefore provide an absolute solubility scale for the fluorescence method.

Source and Purity of Materials:

1. 1-Methylnaphthalene: purity > 99%, Sodium chloride: reagent grade, Ethanol: reagent grade, Water: distilled over a KMnO₄ - NaOH solution and passed through a Sephadex column.

Estimated Errors:

Ambient temperature: ±0.1°C (author)
Mass concentration (m/v) (1): ±3.6% (author)