Gas surface density of H₂O, CO₂, and C₂H₂ at 1 Myr for a disc around a solar-mass star with varying turbulence viscosity levels. We compare results from the standard version of chemcomp (solid lines), where gaseous species are evolved separately, fixing the Schmidt number at Sc_g = 1/3, to our new implementation (dashed lines) in which the Schmidt number is a free parameter, here also fixed to Sc_g = 1/3. We see that the lines overlap, proving the validity of our new approach. Vertical dashed lines indicate the sublimation lines of the displayed species in their respective colour, along with the organics line (dashed brown line).