PC-based spectrophotometric determination of metal-ion concentration in solutions

Date

4-2003

Degree

Bachelor of Science in Applied Physics

College

College of Arts and Sciences (CAS)

Adviser/Committee Chair

Emmanuel A Florido

Abstract

A PC-based method for concentration determination of metal-ions in solutions has been performed. Using an optical absorption set-up, the linear relationship of concentration and absorbance was determined. The measured %transmittance for the various concentrations of each sample solution was measured and saved for analysis. Using the Beer-Lambert's Law, which is the linear relationship between the absorbance and concentration of an absorber of electromagnetic radiation, the absorbance and the wavelength at which it occurs has been determined. Increasing concentrations of Ni(NO3)2 and Co(NO3)2 were prepared and used as samples. An optical absorption set-up, mainly composed of a 150-Watt Halogen light source, a 78225 Oriel Monochromator for scanning from 700nm down to 380nm, and Vactec Solar cell as the sensor. Concentrations ranging from 0.01M to 0.08M and 0.04 to 0.10M were prepared for Ni(NO3)2 and Co(NO3)2, respectively. Samples were scanned in the visible region and the obtained reading were normalized with a blank sample (cuvette and distilled H2O) in order to get the %absorption due to the transition metal ions in solution. The %absorption value for each concentration was tabulated and plotted. The wavelength at which the maximum theoretical absorption for Ni(NO3)2 would be maximum was known to be at 395nm and 680nm, while that of Co(NO3)2 was known to occur at 512nm. Experimental data show that absorption peaks occurred at wavelengths 390nm and 660nm for the Ni(NO3)2 samples and 510nm for Co(NO3)2 samples, respectively. From the Beer's Law plot, experimental data show that there is a linear relation between the concentration of the sample solutions and the %absorption at each wavelength. An accuracy of 77.78% was obtained in estimating the concentration of an unknown sample of Ni(NO3)2 at 0.03M. It can be concluded that the optical absorption set-up can identify or characterize the type of transition metal-ion present in solution and can approximate the concentration of dissolved metal-ions present in solution using Beer's Law.

Language

English

Location

UPLB Main Library Special Collections Section (USCS)

Call Number

Thesis

Document Type

Thesis

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