We propose a complete characterization of the chemical Leslie effect in a Langmuir monolayer of a chiral liquid crystal. To reach this goal, we developed new experimental techniques using an electric field and a humidifier to prepare large monodomains in which the molecules can freely rotate. We also designed six independent experiments to precisely measure the four material constants involved in the dynamics of the monolayer, namely the Leslie coefficient, the rotational viscosity, the curvature elasticity constant and the surface polarization. The relevance of the inverse Leslie effect is also discussed.