Question

On which of the following laws the working of the colorimeter is based upon?
A. Blackman’s law of limiting factor
B. Beer Lambert law
C. Hill’s reaction
D. None of the above

Answer 1

A colorimeter is a device used in colorimetry to measure the absorbance of specific wavelengths of light from a particular solution. To determine the concentration of a known solute in a given solution, a colorimeter can be used. Colorimeter output can be displayed by analog or digital meter and can be shown as transmittance or absorbance.

Complete step by step answer:
Option A Blackman’s law of limiting factor: Blackman enunciated the law of limiting factors in which he states that “When a process is conditioned as to its rapidity by a number of separate factors, the rate of the process is limited by the pace of the 'slowest' factor”. But the working of colorimeters is not based on Blackman’s law of limiting factor.
Hence option A is not correct.
Option B Beer Lambert law: The Beer Lambert law states that the concentration of a solute is proportional to its absorbance. It defines that there is a linear relationship between the concentration and the absorbance of the solution, making it possible to calculate the concentration of the solution by measuring its absorbance. The working of colorimeters is based upon Beer Lambert’s law.
Hence option B is the correct answer.
Option C Hill’s reaction: Hill's reaction is the transfer of electrons from water to Hill's reagent (a non-physiological oxidant) against the chemical potential gradient as part of photosynthesis. Robin Hill demonstrated that the process by which plants produce oxygen is distinct from the process of converting carbon dioxide into sugar.
Since the working of the colorimeter is not based upon Hill’s reaction, option C is not correct.
Option D None of the above: Beer Lambert’s law, which is given in option B is the correct answer.
Hence option D is wrong.

So, the correct answer is “Option B”.

Note:
Beer Lambert's law is applied to the analysis of the mixture by spectrophotometry, without extensive pretreatment of the sample. The determination of bilirubin in plasma samples is an example of this. Pure bilirubin’s spectrum is known so the molar absorbance is known. Only under specific conditions, the Beer-Lambert law maintains linearity.