Consider a vertically falling film of water over an impermeable wall. The film is in contact with a static pool of non-reactive pure gas. The gas diffuses into the water film over the entire height of the falling film. The height of the film is 1.0 m, and its thickness is 10−4m. The velocity of eater, averaged over the film thickness, is 0.01 m s−1. The gas concentration (in kg m−3 ), averaged over the film thickness is

 Where y is the vertical positon in meters measured from the top of the wall. In addition, use the following data and assumptions

• The flow is fully developed

• The width of the film is much larger than the thickness of the film, and the dissolved gas concentration

is invariant over this width

• The solubility of the gas in water, i CA , is constant

• Pure water enters at y = 0

• The evaporation of water is negligible

The mass transfer coefficient on the liquid side (in mm s−1), averaged over the entire height of the falling film is ____(round off to 3 decimal places).