Question

Why did you have to perform the color development step for all of the solutions at the same time for measuring absorbance in spectrometer? Explain in detail.

Answer 1

The colorimetry is bsed on the measurement of the color intensity. More the concentration deeper will be the color. Accoding to Beer-Lambert law when a monocromatic light is passed through the solution then decrease of intensity is proportional to the coc. of the solution & path length.

Mathematically,

                                   Absorption   i.e. A = - logI I / I_{o   ^{= a b c}}

                                                                             _{where a = Extinction co-efficient}

                                                                                         _{b= Path   length}

                                                                                          _{c =Concentration}

When the color is developed one can measure color intensity in the visible region. Simple colorimeter is enough for this purpose.One can observe color intensity depending up on the concentration.The measurement is done at the same time because of air oxidation color may change by keeping the solution . So to mnimize this error the solution color development step for all of the solutions is done at the same time intervals.