Abstract
In order to investigate, how a chemical reaction starts and develops, we select the moment of the impact of a droplet falling into a reactive solution and observe the initial stage of the reaction with a high-speed camera. As examples, we use the pH indicator system with bromothymol blue (BTB) reaction, as well as the Belousov-Zhabotinsky (BZ) reaction forming an excitable medium, in which superthreshold disturbance propagates as an excitation wave and thus gives rise to a reaction-diffusion structure. Focusing on the BTB solution, we observe the color change caused by the droplet containing a pH indicator when impinging on the surface of alkaline solution. Contrary to our expectation, this reaction starts at the equatorial line, and not at the protruding edge of the droplet, where it first gets into touch with its reaction partner. Small vertical fingers emerge from the front line within 1.5 ms. Some arguments make it is likely that heat diffusion is responsible for the finger formation . For the BZ reaction , where due to a redox reaction the color changes from red to blue and vice versa, we do not observe this color change in our experiment. However, the effects on the drop shape (from spherical to ellipsoidal) is the same as observed in the BTB solution. Independently of the chemical systems, a thin needle-like tip developed from the protruding edge within about 300 μs after the drop has touched the solution surface. The emergence of this thin pin cannot be due to chemical processes, but to the physical impact of the droplet.
Access this chapter
Tax calculation will be finalised at checkout
Purchases are for personal use only
References
B. Chance, The accelerated and stopped-flow apparatus II. J. Franklin Inst. 229, 613–640 (1940)
M. Eigen, L. De Maeyer, Relaxation methods, in Technique of Organic Chemistry, vol. 8, ed. by A. Weissberger (John Wiley and Sons, New York, 1963)
J.P. Connelly, M.G. Müller, R. Bassi, R. Groce, A.R. Holzwarth, Femtosecond transient absorption study of carotenoid to chlorophyll energy transfer in the light harvesting complex II of photosystem II. Biochemistry 36, 281–287 (1997)
K. Tsuji, S.C. Müller, Chemical reaction evolving on a droplet. J. Phys. Chem. Lett. 3, 977–989 (2012)
K. Tsuji, S.C. Müller, Observation of a falling droplet with pH indicator. Interfacial Phenom. Heat Transf. 1, 289–299 (2013)
A.N. Zaikin, A.M. Zhabotinsky, Concentration wave propagation in two-dimensional liquid-phase self-oscillating system. Nature 225, 535–537 (1970)
J. Ross, S.C. Müller, C. Vidal, Chemical waves. Science 240, 460–465 (1988)
R. Kapral, K. Showalter (eds.), Chemical Waves and Patterns (Kluwer Academic Press, Dordrecht, 1995)
M. Do-Quang, G. Amberg, The splash of a solid sphere impacting on a liquid surface: numerical simulation of the influence of wetting. Phys. Fluids 21, 022102 (2009)
Y. Couder, E. Fort, C.-H. Gautier, A. Boudaoud, From bouncing to floating: noncoalescence of drops on a fluid bath. Phys. Rev. Lett. 94, 177801 (2005)
D. Beilharz, A. Guyon, E.Q. Li, M.-J. Thoraval, S.T. Thoroddsen, Antibubbles and fine cylindrical sheets of air. J. Fluid Mech. 779, 87–115 (2015)
C. Almarcha, P.M.J. Trevelyan, P. Grosfils, A. De Wit, Chemically driven hydrodynamic instabilities. Phys. Rev. Lett. 104, 044501 (2010)
C. Almarcha, P.M.J. Trevelyan, L.A. Riolfo, A. Zalts, C. El Hasi, A. D’Onofrio, A. De Wit, Active role of a color indicator in Buoyancy-driven instabilities of chemical fronts. J. Phys. Chem. Lett. 1, 752–757 (2010)
M. Böckmann, S.C. Müller, Growth rates of the Buoyancy-driven instability of an autocatalytic reaction front. Phys. Rev. Lett. 85, 2506–2509 (2000)
K. Matthiessen, H. Wilke, S.C. Müller, Influence of surface tension changes on hydrodynamic flow induced by traveling chemical waves. Phys. Rev. E 53, 6056–6060 (1996)
R.H. Lambert, L.J. Gillespie, Heat of neutralization at constant concentration and the heat of ionization of water. J. Am. Chem. Soc. 53, 2632–2639 (1931)
R.C. Weast, M.J. Astle (eds.), CRC Handbook of Chemistry and Physics, 60th edn. (CRC Press, Boca Raton, 1980)
P.V. Hobbs, A.J. Kezweeny, Splashing of a water drop. Science 155, 1112–1114 (1967)
K. Cai, Phenomena of a liquid drop falling to a liquid surface. Exp. Fluids 7, 388–394 (1989)
A. Prosperetti, H.N. Oguz, The impact of drops on liquid surfaces and the underwater noise of rain. Ann. Rev. Fluid Mech. 25, 577–602 (1993)
Acknowledgements
The author thanks Kinko Tsuji for helpful discussions.
Author information
Authors and Affiliations
Corresponding author
Editor information
Editors and Affiliations
Rights and permissions
Copyright information
© 2018 Springer International Publishing AG
About this chapter
Cite this chapter
Müller, S.C. (2018). Observation of Chemical Reactions Induced by Impact of a Droplet. In: Tsuji, K. (eds) The Micro-World Observed by Ultra High-Speed Cameras. Springer, Cham. https://doi.org/10.1007/978-3-319-61491-5_16
Download citation
DOI: https://doi.org/10.1007/978-3-319-61491-5_16
Published:
Publisher Name: Springer, Cham
Print ISBN: 978-3-319-61490-8
Online ISBN: 978-3-319-61491-5
eBook Packages: EngineeringEngineering (R0)