OCR Text |
Show - 4 - Substituted in Equation 4, they give: loo rK. = -/> - L^ dTA t o. o 9f< sj T- a. ooo a^ g& T*- E This equation is presented graphically in Figure 1. The agreement between observed and computed values is excellent. b) What does the concept of " effective mean temperature eT " signify? As temperature rises, the inversion rates, and with them the accompany-inversion constants K, increase rapidly. The temperature quotient of these constants amounts to 3.8 - 5 9 for each 10° temperature difference. When the inversion takes place in a sugar solution, whose temperature is not held constant but allowed to vary in the course of the observation, the periods of higher ambient temperature have 1 significantly greater effect on the overall inversion effect for the total period than do those of lower temperature. The observed total amount of inversion for the investigation period ( quantity of invert sugar formed) corresponds to an " effective mean temperature" which must be higher than the arithmetic mean of the temperature variations. The effective mean temperature, designated as eT , does not correspond to the arithmetic temperature mean of an observation period, but rather to an exponential mean. Not only cane sugar inversion, but all other chemical and biochemical reactions occur more rapidly at higher temperatures than at low ones { RGT-Law of Van't Hoff, 1884). When a reaction takes place predominantly in one direction during a period involving various temperature levels, the given reaction effect R at the end of the period exhibits a stronger influence from the higher temperature levels than from the lower- The exponential mean temperature eT measured with help of the sugar inversion departs the wider from the arithmetic mean, the greater was the |