How does pressure affect the color of reaction medium with equimolar amounts or reactants and products at equilibrium?

Chlorine gas is pale yellow-green, and both hydrogen and hydrogen chloride are colorless gases. According to the [Le Chatelier's principle](https://en.wikipedia.org/wiki/Le_Chatelier%27s_principle), the change in pressure will not affect the following equilibrium:


$$\ce{H2(g) + \color{green}{Cl2(g)} <=> 2HCl(g)}$$


Reduced volume will increase the partial pressures of gases. Will the color of the medium remain the same, or acquire a more saturated green tint due to increased concentration of chlorine gas?




By (isothermal) compression of such a system, the equilibrium is not shifted, so the chlorine mass and molar amount stays constant (with possible tiny changes due non-ideal behaviour of gases).


But as the system volume decreased, concentration (or equivalently partial pressure) of components increased and the perceived chlorine color intensified.


If compression of the system were done by a linear way, like by transparent piston in a cylindrical vessel, the light absorption along the direction of this shortened path would be the same. As the shorter path is balanced by more intense absorption.


It means, the gas would be perceived in that direction as if colour did not change, but with more intense color in perpendicular directions.


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