| Papers [289-300] of 316 :: [Page 25 of 27] | | Go to page : <— 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 —> | |
|
|
Magnetism, 2000.
An experimental analysis of magnetic susceptibility.
1,543 words (approx. 6.2 pages), 4 sources, $ 50.95
»
Click here to show/hide summary
From the Paper
"The synthesis of a magnetic susceptibility standard proved to be Hg[Co(NCS)4] through mercury analysis and magnetic measurements. Magnetic susceptibility characterization of four nickel(II) complexes, Ni(Et2en)2Cl2-2H20, Ni(Et2en)2(NCS)2, Ni(Et2en)2(NO3)2, and Ni(Et2en)2I2, is reported. Et2en is a bidentate ligand, which is bonded strongly to the Ni(II) metal center.
Ni(Et2en)2Cl2-2H2O and Ni(Et2en)2(NCS)2 were both paramagnetic with two unpaired electrons and had Ueff values of 3.17 B.M. and 3.20 B.M., respectively. Ni(Et2en)2(NO3)2 and Ni(Et2en)2I2 were both diamagnetic with no unpaired electrons and had Ueff values of 1.80 B.M. and 1.71 B.M., respectively. The color of the compounds correlates with their magnetic properties, where blue to violet compounds are paramagnetic and yellow to red complexes are diamagnetic."
| |
|
Stereochemistry, 2000.
Stereochemistry of Co III trien X2 complexes and resolution of the Trien Co III enantiomers.
1,238 words (approx. 5.0 pages), 3 sources, $ 42.95
»
Click here to show/hide summary
From the Paper
"In this experiment three Co(III)trienX2 complexes were prepared. These complexes were cis-alpha-[Co(trien)Cl2]Cl 1, cis-beta-[Co(trien)Cl2]Cl-0.5H2O 2, and trans-[Co(trien)Cl2]Cl-1.5H2O 3. The trien ligand is a tetradentate ligand, which is a strong field ligand. Once the trien ligand is coordinated to the metal the molecule's energy is lowered due to the chelate effect. The three complexes were studied using infrared and UV/Visible spectroscopy.
Also prepared in this experiment was the cation [Co(en)3]3+ which has two enantiomers. The ligand ethylenediamine is a strong field ligand, which is bidentate. This ligand also lowers the energy of the molecule through the chelate effect. The chelate rings remove a center of inversion, which removes the chance of an improper rotation axis and leads to an optically active molecule. The optical purity of the two enantiomers was calculated by measuring their specific rotation using a polarmetry apparatus."
| |
|
Solid-Liquid Phase Diagram, 2001.
An experiment using a procedure known as thermal anaylsis.
1,820 words (approx. 7.3 pages), 3 sources, $ 58.95
»
Click here to show/hide summary
From the Paper
"A solid-liquid phase diagram was constructed for a naphthalene - diphenylamine system. The phase diagram was constructed using the procedure known as thermal analysis. Thermal analysis allows for the determination of phase boundaries. A graph of the phase boundaries was then plotted versus mole fraction of naphthalene. From the graph the eutectic composition of the system was determined to be 0.39 + 0.1 moles of naphthalene and 0.61 + 0.1 moles of diphenylamine. The ln of mole fractions of naphthalene were then plotted versus 1/Temperature and from these graphs the heat of fusion and melting temperature for Ha and Hb were determined to be 99.49 + 2.0 KJ/mol and 17.38 KJ/mol, respectively. The Ta and Tb were determined to be 29.0 + 2.0 oC and 81.4 + 2.0 oC, respectively."
| |
|
Scientific Experiment on Polyvinyl Alcohol, 2001.
Determination of the molecular weight of polyvinyl alcohol by viscosity.
1,244 words (approx. 5.0 pages), 2 sources, $ 42.95
»
Click here to show/hide summary
From the Paper
"Cleaved and uncleaved solutions of PVOH were involved in viscosity measurements. These measurements were undertaken so as to determine the molecular weight of the PVOH solutions. The apparatus constant for the Ostwald viscometer was calculated to be 1.435 x 10-4. The specific viscosity was also determined and used to plot graphs of hsp/c vs. c, and 1/c ln h/ho vs. c. From these plots the intrinsic viscosity was extrapolated to a concentration of zero.
The values of the molecular weights were averaged and reported for both the uncleaved and cleaved product. The values obtained for Mv were 26,731.3 g/mol and 4615.4 g/mol, respectively. The values obtained for Mn were 14145.6 g/mol and 2442 g/mol, respectively. The values obtained for D for all the graphs was 5.89 x 10-3."
| |
|
Liquid-Vapour Equilibrium of Acetone and Cyclohexane, 2000.
Analysis of a lab experiment on acetone and cyclohexane.
1,188 words (approx. 4.8 pages), 3 sources, $ 40.95
»
Click here to show/hide summary
From the Paper
"A phase diagram was constructed for an acetone - cyclohexane system. The phase diagram was constructed from the simple distillation of acetone and cyclohexane. Samples were taken of the liquid phase and vapour phase of both components. The refractive index was then determined for each sample. The data from the refractive index then allowed for the construction of the phase diagram. As determined from the phase diagram the boiling point of the azeotrope was 53oC and the percent mole composition of the azeotrope was 67.0 + 2.0% acetone and 33.0 + 2.0% cyclohexane."
| |
|
Cyanazine, 2000.
Extensive and illustrated examination of cyanazine.
2,486 words (approx. 9.9 pages), 13 sources, $ 75.95
»
Click here to show/hide summary
Abstract
This paper takes a look at the applications, characterization, adverse effects and toxicity of cyanazine.
From the Paper
"The use of herbicides has led to their detection in various parts of our environment. One particular herbicide, which has been found in our water, is cyanazine. The detection of cyanazine in our lakes and sources of drinking water is of great importance because it has the potential to affect numerous organisms and biological systems. Cyanazine is a selective herbicide, which is used to control annual grass and broadleaf weeds in a variety of crops1. Cyanazine is a member of the triazine herbicide family, and has been in use since 19713. At one time cyanazine was the fourth most widely used synthetic chemical pesticide in the United States3. Cyanazine may be released into the atmosphere by the application of the herbicide to a field or by vapor drift or through precipitation. Cyanazine once released to the environment will readily partition to water where it may be found in sources of drinking water."
| |
|
Analysis of Organotin Compounds, 1999.
A look at the chemicals used to make plastics and other important products.
1,883 words (approx. 7.5 pages), 1 source, $ 60.95
»
Click here to show/hide summary
From the Paper
"In recent years attention has been focused on the need to analyze organotin compounds. When tin is combined with materials that contain carbon, it is called an organotin compound and it is used to make plastics, food packages, plastic pipes, pesticides, paints, and pest repellents. Organotin compounds, specifically tributyltin and triphenyltin, should be regarded as highly toxic and when used in marine environments lead to severe problems for the local wildlife."
| |
|
Solubility and Ionic Strength, 2001.
A laboratory analysis concerning the solubilities of various solutions containing different ionic strengths.
1,722 words (approx. 6.9 pages), 2 sources, $ 55.95
»
Click here to show/hide summary
From the Paper
"Determined in this experiment were the solubilities and mean activity coefficients of various solutions containing different ionic strengths. These measurements were achieved by the simple distillation of calcium iodate solutions against thiosulphate and a starch indicator. The data obtained from these results led to the determination of the concentrations of the calcium salt, the concentration of the iodate salt, C, u, u1/2 and [2A(u)1/2]/[1 + B(u)1/2]. A plot of log10C versus [2A(u)1/2]/[1 + B(u)1/2] allowed for the calculation of K. The value of K obtained was 1.0789 x 10-6 + 0.0037. Three different values of the mean activity coefficients were tabulated. From the tabulated values it was observed that the experimental values were larger than the theoretical values."
| |
|
Absorption of Acetic Acid from Solution, 2001.
An experiment concerning the the Langmuir Isotherm.
1,522 words (approx. 6.1 pages), 2 sources, $ 50.95
»
Click here to show/hide summary
Abstract
The objective of this experiment was to determine the adsorption of various acetic acid solutions onto charcoal. This experiment obeyed the Langmuir isotherm because the plot of C/N versus C proved to be linear. This shows that the adsorption equilibrium is essentially ideal and there is a definite set of sites of adsorption.
| |
|
The Synthesis of 3-Carbethoxycoumarin, 2001.
Describes the preparation of 3-carbethoxycoumarin 4, a fused-ring heterocycle.
1,242 words (approx. 5.0 pages), 3 sources, $ 42.95
»
Click here to show/hide summary
From the Paper
"The reaction of salicylaldehyde 1 with diethyl malonate 2 was reacted in a basic environment with piperidine 3. The reaction was a base catalysed condensation which also involved a transesterification step to produce 3-carbethoxycoumarin 4. The purification of 3-carbethoxycoumarin 4 was achieved through filtration. The experiment was successful with the product being identified as 3-carbethoxycioumarin 4; it was identified as such through its' melting point, IR, 1H NMR, and 13C NMR."
| |
|
Surface Tension of n-butanol Solutions, 2001.
A look at adsorption in surface layers.
2,151 words (approx. 8.6 pages), 2 sources, $ 67.95
»
Click here to show/hide summary
From the Paper
"The surface tension of deionized water and eight solution of n-butanol were determined using the capillary-rise method. The radius of the capillary was determined to be 3.59 x 10-2 + 0.15 cm. The value of the radius of the capillary allowed for the determination of the surface tensions of the eight n-butanol solutions. The surface tensions were then plotted versus the natural logarithm of the concentrations of the n-butanol solutions. The slope of the graph was then used to determine the amount of n-butanol adsorbed. This value was calculated to be 3.52 x 10-10 + 0.71 mol/cm2. This value was converted into 2.12 x 1014 + 0.71 molecules/cm2. The effective cross section area of one molecule of n-butanol was determined to be 4.72 x 10-15 + 0.71 cm2. The value of Avogrado's number was calculated using the value of n2/A and the molar volume of n-butanol. Avogrado's number was determined to be 2.74 x 1024 + 0.71."
| |
|
The Co III Salen Complex, 2000.
1,170 words (approx. 4.7 pages), 5 sources, $ 40.95
»
Click here to show/hide summary
Abstract
This paper discusses the results and conclusions from a chemistry experiment about the preparation and reversible oxygenation of the Co(II)(salen) complex.
From the Paper
"The tetradentate N,N'-bis(salicylaldehyde)ethylenediimine 3, SalenH2, was prepared by the Schiff's base condensation of salicylaldehyde 1 and ethylenediamine 2 via the elimination of water1. SalenH2 3, was then used to prepare the red inactive form of the complex N,N'-bis(salicylaldehyde)ethylenediimino)cobalt(II) 4, Co(salen).
The inactive form of Co(salen) 4, consists of dimeric units in which the cobalt atom of one molecule interacts with an oxygen atom lone pair of the second molecule1. The inactive form of Co(salen) was investigated in DMSO in which oxygen is rapidly absorbed. The binding of the oxygen to cobalt was measured and was found that one mole of oxygen bound to two moles of cobalt. Values of the ratio for oxygen to cobalt are dependent on the nature of the ligands, temperature and solvents."
|
|
|
