Hello. Is there a way to calculate properties of a gas, given only it's composition? I.e. let's say i want to know what would a planet look like with an atmosphere of a mix of 50% gaseous sulphur and 50% gaseous mercury, at 500*C and surface pressure of half that of Earth. How would i go about calculating that just from basic laws? I kind of know where to start regarding the pressure, density and so on, but i have no idea how to get the refractive index and light absorption by wavelength, for example. Is it even possible? If so, what should i look for?