The mechanism of a redox indicator reaction: The kinetics of oxidation of ferrocyphen by nitrous acid

1979 ◽  
Vol 295 (4) ◽  
pp. 252-255 ◽  
Author(s):  
Patricio Reveco ◽  
Geoffrey Stedman
Keyword(s):  
Nitrous Acid ◽  
Kinetics Of Oxidation ◽  
Indicator Reaction ◽  
Redox Indicator ◽  
Kinetics Of

Kinetics of oxidation of nitrite by aqueous chlorine

1973 ◽  
Vol 26 (9) ◽  
pp. 1857 ◽  
Author(s):  
JN Pendlebury ◽  
RH Smith
Keyword(s):  
Nitrous Acid ◽  
Ionization Constant ◽  
Initial Step ◽  
The Other ◽  
Stopped Flow ◽  
Unimolecular Decomposition ◽  
Solution Ph ◽  
Kinetics Of Oxidation ◽  
Aqueous Acid ◽  
Kinetics Of

The kinetics of oxidation of nitrite to nitrate by chlorine in aqueous acid solution (pH 0-1) have been studied using a spectrophotometric stopped flow technique. The rate law is ���������������� -d[Cl2]a/dt =([Cl2][NO2-]/Ka[Cl-]2)(f+g[HNO2]) where [Cl2]a = [Cl2]+[Cl3-] and where Ka is the ionization constant for nitrous acid. At 298.2 K and ionic strength 2.75M, f = 60.8�0.5 mol2 l-2 s-1 and g = (2.35�0.05)x105 mol l-1 s-1: the associated activation energies are 68�3 and 44�2 kJ mol-1 respectively. A mechanism is proposed involving the reversible initial step: �������������������������� NO2-+Cl2 ↔ NO2Cl+Cl- with the NO2Cl undergoing two parallel subsequent reactions, one a unimolecular decomposition and the other an attack by HNO2 upon NO2Cl. ��� Oxidation of nitrite by the three halogens, Cl2, Br2, I2, is discussed.

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