15 



TEMPERATURE COEFFICIENT OF THE REACTION VELOCITY. 



The iiiHuence of temperature on the reaction velocity may l)e 

 found from the four experiments, the results of which are plotted 

 in tigs. 2 and 3, since they were all made with the same sample of 

 oxide. We must choose for comparison the reaction velocities 

 at corresponding points in the several experiments. The apices 

 of the curves constitute such a series of corresponding points. 

 The maximum velocities at the four temperatures, 327°, 332.5°, 

 352.2°, 353.3°, were, respectively, 0.0106, 0.0134, 0.0316, and 

 0.0335 per cent per second. If we plot the logarithms of these 

 four numbers on the one hand and the corresponding tempera- 

 tures on the other the resulting points lie almost precisely on a 

 straight line whose slant is given by the equation 



'^ = 0.0185, 



Or, Iiy the integrated form, 



log,„Jr = 0.0185(T-T,). 



It is customary to express the influeneo of t('mi)erature U[)on 

 reaction velocity by means of the quotient of the velocity at one 

 temperature divided by the velocity at a temperature 10° lower. 

 This quotient can be easily found in the present case from the 

 above equation. Since T, — T^^IO, 



^"' = lo'j 0. 1.S5= 1.53. 



In other words, when the temperature rises 10° tlie vt'locity 

 increases by about 50 per cent. This increase is less than that of 

 most reactions, but corroborates the idea of Van't IIotY,' wlio writes 

 concerning this quotient: 



Bedeutend weniger als Verdoppelung zeigt nur die Zerlegung von riios- 

 phor- und Arsenwas.-erstoff. Das hiingt al)er vielleicht iiiit iUt liohen 

 Beobachtungsteinperatur zusaniiiien, denn in der grosf^en Mt^lirheit der liis 

 jetzt beobachteten Fiille nimmt das Geschwindigkeitsverhfiltnis liir 10° luit 

 steigender Temperatur ab. 



' Vorlennngen neher Theor. n. PhijK. Cfip)n. 



