Resumen:
The students of a General Chemistry class made absorbance measurements in different
concentration methylene blue solutions, through the color analysis of solutions pictures. They obtained a calibration curve with a R2=0.9904 that was used for the concentration determination of dye samples exposed to sunlight in variable degradation times with TiO2 as catalyst. The colorimetric method essayed is easy to use and it may be applied in laboratories where a UV-Vis spectrophotometer is not available.