colorimetry

Question

even if there is no experimental error, explain why the graphs plotted cannot be an absolute straight line.

Answer 1

According to Beer's law, the absorbance of the sample solution is directly proportional to its concentration. Therfore, a straight line is obtained in the plot of absorbance against concentration if the coloured solution obeys Beer's law. However, most coloured solutions obey Beer's law at low to moderate concentrations. Usually, if the concentration of the coloured solution is NOT low enough, the curve at the region of higher concentrations of the graph will bend a little bit downwards instead of a straight line.

2007-02-16 15:00:11 補充：
Reference :http://www.wellesley.edu/Chemistry/chem120/beerslaw.html