ANS:C - known

For experimental determination of mass transfer coefficient by a wetted wall tower, the mass transfer area needs to be known. In a wetted wall tower experiment, the inner surface of the tower wall is kept wetted with a liquid film, and the gas or vapor phase flows over this wetted surface. The mass transfer coefficient 𝑘GkG​ is then determined by measuring the rate of mass transfer from the gas or vapor phase to the liquid film. This rate of mass transfer is proportional to the concentration gradient of the solute in the gas phase and the surface area over which the mass transfer occurs. By knowing the surface area of the wetted wall, the concentration gradients, and other relevant parameters, one can calculate the mass transfer coefficient using appropriate experimental techniques and mathematical models, such as the film theory or empirical correlations. Therefore, for experimental determination of the mass transfer coefficient in a wetted wall tower, knowing the mass transfer area is essential.