Hatta number

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The Hatta number (Ha) was developed by Shirôji Hatta, who taught at Tohoku University.[1] It is a dimensionless parameter that compares the rate of reaction in a liquid film to the rate of diffusion through the film.[2] For a second order reaction (rA = k2CBCA), the maximum rate of reaction assumes that the liquid film is saturated with gas at the interfacial concentration (CA,i); thus, the maximum rate of reaction is k2CB,bulkCA,iδL.

For a reaction mth order in A and nth order in B:

It is an important parameter used in Chemical Reaction Engineering.


  1. ^ S. Hatta, Technological Reports of Tôhoku University, 10, 613-622 (1932).
  2. ^ R.B. Bird, W.E. Stewart, E.N. Lightfoot, Transport Phenomena, 2nd ed. John Wiley & Sons, 2002

See also[edit]