Bray–Liebhafsky reaction
The Bray–Liebhafsky reaction is a
by the iodate. He observed that the concentration of iodine molecules oscillated periodically and that hydrogen peroxide was consumed during the reaction.An increase in temperature reduces the cycle in the range of hours. This oscillating reaction consisting of
free radical on non-radical steps was investigated further by his student Herman A. Liebhafsky,[2]
hence the name Bray–Liebhafsky reaction. During this period, most chemists rejected the phenomenon and tried to explain the oscillation by invoking heterogeneous impurities.
A fundamental property of this system is that hydrogen peroxide has a
:- 5 H2O2 + I2 → 2 IO−
3 + 2 H+ + 4 H2O
and the reduction of iodate back to iodine:
- 5 H2O2 + 2 IO−
3 + 2 H+ → I2 + 5 O2 + 6 H2O
Between these two reactions the system oscillates causing a concentration jump of the iodide and the oxygen production. The net reaction is:
- 2 H2O2 → 2 H2O + O2
necessitating a
catalyst
and IO−3.
References
- .
- .
Further reading
- Treindl, Ludovit; Noyes, Richard M. (1993). "A new explanation of the oscillations in the Bray–Liebhafsky reaction". The Journal of Physical Chemistry. 97 (43): 11354. .
- Edelson, David; Noyes, Richard M. (1979). "Detailed calculations modeling the oscillatory Bray–Liebhafsky reaction". The Journal of Physical Chemistry. 83 (2): 212. .
- Schmitz, Guy (1999). "Effects of oxygen on the Bray–Liebhafsky reaction". Physical Chemistry Chemical Physics. 1 (19): 4605–4608. doi:10.1039/a904722k.
- Valent, Ivan; Adamčikova, Ľubica; Sevčik, Peter (1998). "Simulations of the Iodine Interphase Transport Effect on the Oscillating Bray−Liebhafsky Reaction". The Journal of Physical Chemistry A. 102 (39): 7576. .
- Buchholtz, Frank G.; Broecker, Sebastian (1998). "Oscillations of the Bray–Liebhafsky Reaction at Low Flow Rates in a Continuous Flow Stirred Tank Reactor". The Journal of Physical Chemistry A. 102 (9): 1556. .
- Stanisavljev, Dragomir; Begović, Nebojša; Vukojević, Vladana (1998). "Influence of Heavy Water on the Bray−Liebhafsky Oscillating Reaction". The Journal of Physical Chemistry A. 102 (35): 6887. .
- Jiménez Prieto, Rafael; Silva, Manuel; Pérez Bendito, Dolores (1998). "Critical Review: Approaching the use of oscillating reactions for analytical monitoring". The Analyst. 123 (2): 1. doi:10.1039/a703354k.