• 作者： 何武雄
• 作者服務機構： 國立中興大學化學系
• 中文摘要： 在單位離子?度，440 nm波長下用分光光度法由測定吸光度來研究亞硝酸還原六價鉻的反應。六價鉻消失的初反應速 率遵照如下速率方程式： d(Cr(VI))/dt=(k0+k1)(H+)) (HNO2) (CrO3ONC-) 在15.0℃,25.0℃和35.0℃速率常數k0之?分別?（2.51 ±0.04)× 1O-2， （5.64±0.11) × 1O-2 ，和(7.85 土0.44)×10-2 M-1 sec-1 。在25.0℃ k0 途徑，活化熱含量(enthalpy)?9.5 ±2.3 kcal/mole ，活化熵（entropy)?一32.7±7.5 e. u.。在15.0℃， 25.0°C ，和35.0°C速率常數k1之?分別?0.039±0.006， 0.159±0.016和0.51 ±0.06M2sec-1 。在25.0°C k1 途徑， 熱含量(enthalpy)?22.0±0.7 kcal/mole ，活化熵（entropy)?11.5土2.2e.u.方程式CrO3ONO-+H2O=HCrO4-+ HNO2之濃度平衡常數K在15.0°C, 25.0°C ,和35.0°C分別?0.0145， 0.0139 ，和0.0092M。
• 英文摘要： The kinetics of the reduction of chromium(VI) by nitrous acid was studied spectrophotome-trically using solutions with absorbance values at 440 nm of unit ionic strength. The initial rate of disappearance of chromium(VI) obeys the rate equation: -d(Cr(Vl)/dt = (k0 +k1(H+)(HNO2) (CrO3ONO-) The values of the rate constant k0 at 15.0, 25.0, and 35.0°C are (2.51 ±0.04) × 10-2, (5.64±0.11)× 10-2, and (7.85±0.44)Xl0-3M-1sec-1, respectively. The enthalpy and entropy of activation of the k0 path at 25.0°C are 9.5±2.3 kcal/mole and —32.7±7.5 e. u., respectively. The values of the rate constant k1 at 15.0, 25.0, and 35.0°C are 0.039±0.006, 0.159±0.016, 0.51 ±0.06 M2 sec-1, respectively. The enthalpy and entropy of activation of the k1 path at 25.0°C are 22.0±0.7 kcal/mole and 11.5±2.2 e. u., respectively. The values of the concentration equilibrium constant K at 15.0, 25.0, and 35.0°C of the reaction CrO,ONO-+H20=HCr04-+HN02 are 0.0145, 0.0139, and 0.0092 M, respectively.
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