Demonstrations Color Value

In this demonstration, color value was changed by dilution. How else can color value be changed ... 

Demonstration 1.3 Copper Sulfate Dilution, Mass Percent, and Color Value. . 54... 

Polymerization conditions with temperatures of 60 °C were mild compared with conventional ATRP in solution, where typically temperatures around 100 °C are applied. Despite these mild conditions, high polymerization rates and high conversion within only 3 h were achieved. Moreover, it could be demonstrated that the catalyst, being covalently bound to the surfactant, can easily be removed by filtering off the latex and subsequent washing with methanol. By this procedure the copper content of the resulting PMMA was reduced from the theoretical value of 0.73% to 0.06% and the polymer appeared colorless while the washing fraction was colored [65]. 

Fig. 19. Simulation of soot deposition on a filter wall, (a) Evolution of soot deposits (gray) in the wall (black is solid, white is pore space) and incipient cake formation (b) pressure drop as function of challenge soot mass demonstrating the deep-bed to cake filtration transition (c) visualization of soot deposition in an extruded ceramic (granular) filter wall and (d) development of soot deposits (black) and soot mass fraction in the wall (solid material is gray) to the onset of cake formation. Soot mass fraction scale is from 0 (violet) to the inflow value (red). In (d) the velocity on a section through the filter wall is shown, with overlay of the soot deposit shapes (see Plate 9 in Color Plate Section at the end of this book).

A basic tenet of this book is to introduce and illustrate topics with concrete, interesting examples. In addition to their pedagogic value, Chapter Openers, Boxes, Demonstrations, and Color Plates are intended to help lighten the load of a very dense subject. I hope you will find these features interesting and informative. Chapter Openers show the relevance of analytical chemistry to the real world and to other disciplines of science. I can t come to your classroom to present Chemical Demonstrations, but I can tell you about some of my favorites and show you color photos of how they look. Color Plates are located near the center of the book. Boxes discuss interesting topics related to what you are studying or they amplify points in the text. 

The value of a hue changes as a solution is diluted because, in a constant volume, the number of colored particles (ions) is reduced. There are fewer ions to reflect colored light waves. In this demonstration, the number of... 

At the end of 30 min., read the intensity of the color in each test tube in a spectrophotometer. Your instructor will demonstrate the use of the spectrophotometer. (For reading absorbance values in spectrophotometers, read the details in Experiment 49, p. 497.)... 

Horigome and Kandatsu (63) prepared a Fuki (Petasites japon-icus miq. a traditional food plant in Japan) acetone-powder with a high o-diphenol oxidase activity. When the powder was added to a mixture of caffeic acid and casein, casein was gradually pigmented. A feeding test with rats demonstrated that there was a close relationship between the decrease in biological value of the pigmented casein and its color intensity. 

---