Spectrophotometric Determination of Sodium Nitroprusside by Coupling with Diazotized p-Nitroaniline and Determination of Thermodynamic Parameters | ||
| Rafidain Journal of Science | ||
| Article 11, Volume 22, Issue 5, July 2011, Pages 119-128 PDF (0 K) | ||
| DOI: 10.33899/rjs.2011.6525 | ||
| Authors | ||
| Hayfa M. Jassim; Batool B. Ibraheem; Kasim Y. Rahawi | ||
| Abstract | ||
| The coupling reaction of sodium nitroprusside (SNP) with diazotized p-nitroaniline (DPNA) in basic media has been studied using spectrophotometric method. The intense yellow water-soluble associated species which was formed, showed maximum absorbance at 278 and 396 nm, depending on the concentration of SNP. Two calibration curves have been obtained for the determination of SNP with DPNA. The first curve (max=278 nm) obeys Beer's law over the range 25-300 µg/25 ml, with a regression equation of A=0.0027C+ 0.0747 ; R2 = 0.9853. The second curve (max=396 nm) obeys Beer's law over the range 300-5000 µg/25 ml, with a regression equation of A= 0.0002C+ 0.0439 ; R2=0.9943. The stability constants (K) were determined at different temperatures (283, 288, 293, 298 and 303K). Van't Hoof plot was obtained from which the thermodynamic parameters (free energy change ΔG, enthalpy change ΔH, and entropy change ΔS) were obtained. | ||
| Keywords | ||
| Sodium Nitroprusside; diazotized p; Nitroaniline; Spectrophotometric Determination; Stability Constant; thermodynamic parameters | ||
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