Spectrometer Lab Report

Introduction

Spectrophotometry is one of the methods in which we can measure how much the chemical substance absorbs light by using the intense light transmitted of a narrow wavelength ranging from 400–700 nm, then compares the result of the sample with an initial blank/neutral solution which was placed before the sample as a basis of the data needed. This optical instrument is widely used in areas like biological sciences and etc. [1] Measurement services are available for dissemination of the scales of reflectance and transmittance maintained by the reference instruments. The primary purpose is to provide traceability to the scales, not for research on particular test items. These services are available as either calibrations or standard reference materials. For a calibration service the customer generally supplies the test item, which is measured under the spectral and geometrical conditions specified by the customer. Standard reference materials are available for immediate purchase, and are calibrated under specific spectral and geometrical conditions [1]

‘According to Beer Lambert Law,

Absorbance, A = bc

 is the molar absorptivity coefficient in L mol-1 cm-1, a constant for a particular compound, different compound has different molar absorptivity.

b is the path length (in cm), the path length of the cuvette in which the sample is contained

c is the concentration of the compound in solution, in mol L-1

The Beer-Lambert law can be used to calculate the concentration of a solution if its molar absorptivity coefficient is known. To determine the molar absorptivity coefficient, we measure the absorbance of a known concentration of solution and then solve it by rearranging the equation as below:

In this experiment, we are going to measure the absorption rather than the transmission of light, and determine the molar absorptivity coefficient of bromophenol blue by using Beer-Lambert law.

The Beer-Lambert Law can also be...