Determining Complex Ion Composition by Continuous Variations Method
I. Abstract This experiment aimed to determine the composition of Ni2+- ethylenediamine (en) complexes through Continuous Variations method as well as the number of ligands (n values). This nondestructive method is preferred in determining the amount of complexes present which will also not disrupt the equilibria. 0.3M concentrations of nickel sulfate hexahydrate and ethylenediamene are mixed at certain stoichiometric ratios of 0.3, 0.4, 0.5, 0.6, 0.7, 0.8 and 0.9 to form several complexes. Using the UV-Vis Spectrometer, the absorbances are taken at wavelengths 530, 545, 578, 622 and 640 nm due to the emergence of several complex compositions. The values of corrected absorbances and the mole fraction of en (X) are plotted to obtain a curve. From these curves, an intersection from the 2 trend lines are determined, denoting the values of x, needed for the determination of n. The process led the group with similar values of n which is 1, indicating the amount of ligands bounded per nickel atom. II. Keywords 1. Absorbance – measurement of the amount or quantity of light a sample absorbs
2. Cuvette – a small tube closed at one end, which serves as a sample holder for Spectroscopic experiments
3. Complexes – ions containing metals bonded to its molecules or other ions; reactions of these are called Complexation
4. Spectrum – electromagnetic radiation either emitted or absorbed by substances
5. Ligand – the species that binds to the metal ions
III. Introduction When light interacts with matter, the structures and properties of atoms and molecules are determined. This technique is spectroscopy where it absorbs, emits, or scatters electromagnetic radiation. Electromagnetic radiation has particle-like properties having photons and quantum and wave-like properties with frequency and wavelength. To make molecules visible through light, the wavelength of the molecule should be longer than the wavelength of the light.
One spectroscopic
2. Cuvette – a small tube closed at one end, which serves as a sample holder for Spectroscopic experiments
3. Complexes – ions containing metals bonded to its molecules or other ions; reactions of these are called Complexation
4. Spectrum – electromagnetic radiation either emitted or absorbed by substances
5. Ligand – the species that binds to the metal ions
III. Introduction When light interacts with matter, the structures and properties of atoms and molecules are determined. This technique is spectroscopy where it absorbs, emits, or scatters electromagnetic radiation. Electromagnetic radiation has particle-like properties having photons and quantum and wave-like properties with frequency and wavelength. To make molecules visible through light, the wavelength of the molecule should be longer than the wavelength of the light.
One spectroscopic
References: 1. CHP - Spectroscopy. (n.d.). Retrieved February 10, 2014, from http://www.files.chem.vt.edu/chem-ed/spec/spectros.html 2. COMPLEX FORMATION: THE METHOD OF CONTINUOUS VARIATION USING SPECTROPHOTOMETRY. (n.d.). Retrieved February 10, 2014, from http://www.chem.wilkes.edu/~mencer/pdf_docs/FeSCN_Proc.pdf 3. LBYCH29 Laboratory Manual 4. Organic Chemistry On Line. (n.d.). Retrieved February 10, 2014, from http://www2.chemistry.msu.edu/faculty/reusch/VirtTxtJml/Spectrpy/spectro.htm 5. Skoog, D. A., Holler, F. J., & Nieman, T. A. (1998). Principles of instrumental analysis. Philadelphia: Saunders College Pub.