Chemical reactions measuring progress

In reaction kinetics, the object of interest is the progress of a chemical reaction measured in terms of the change in concentration of the corresponding reactants and products. The change of a component s amount in time is defined as the reaction rate of this component. Assuming constant volume this equals the concentration of this component. The reaction rate r, of component j can be expressed as the change in concentration Cj over time ... 

A final requirement for a chemical kinetic method of analysis is that it must be possible to monitor the reaction s progress by following the change in concentration for one of the reactants or products as a function of time. Which species is used is not important thus, in a quantitative analysis the rate can be measured by monitoring the analyte, a reagent reacting with the analyte, or a product. For example, the concentration of phosphate can be determined by monitoring its reaction with Mo(VI) to form 12-molybdophosphoric acid (12-MPA). 

There are other ways to appreciate the catalytic potency of enzymes in addition to that provided above. A second way to understand the same point is to accurately measure ratios between rates of enzyme-catalyzed reactions and the corresponding uncatalyzed reactions under the same conditions, a refinement of the qualitative argument just made. These ratios are frequently not easy to obtain since the rates of the uncatalyzed reactions may be so slow as to make them exceedingly difficult to measure. Nonetheless, a number of these ratios are known and they typically vary between abont 10 (one thousand) and 10 (one quadrillion), truly enormous values. To help understand just how large 10 is, consider a chemical reaction begun at the time of the creation of our solar system whose progress would be barely detectable at the present day. That same reaction would be nearly complete in 1 minute if catalyzed IQi -fold. 

In 1860, an international conference of chemists convened to discuss how the masses of atoms of different elements could be measured and compared with one another. (As we explore in Section 9.2, knowing the relative masses of atoms helps chemists understand and control chemical reactions.) At the time, there was little agreement because different chemists using different experimental procedures and assuming different theories came up with different results. Progress in chemistry was stymied by this problem. 

Decibel The unit nsed for the measurement of the intensity of sound on a logarithmic scale based on measurements of sound intensity in watts per square meter and related to a reference. For instance, 10 W/m is the intensity of the quietest sound perceptible to the hnman ear Decomposition The breakdown of chemical snbstances into other substances or parts of componnds nsnally associated with heat or chemical reactions Delayed health effect A disease or an injnry that happens as a resnlt of exposure to chemical substances that might have occnrred in the past Delney clause An amendment enacted in 1958 to the Pnre Food Act that prohibits the addition to food of all detectable amonnts of a carcinogen Dementia (senile dementia) An acqnired progressive impairment of intellectual function... 

---