You are using a spectrophotometer and need to start your experiment with a "blank" sample. What is the purpose of the blank? What is the absorbance reading of the blank? What is the transmittance of the blank? (in % )
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Step 1: The purpose of the blank sample is to calibrate the spectrophotometer and to only measure the absorbance of the sample of interest in the solution without interference from other components in the solution. Show more…
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If a certain pigment has a high absorbance for a particular wavelength of light, will its transmittance be high or low at that same wavelength? The blank contains only the ______ that is in the sample cuvette. b. What is a blank used to do when using a spectrophotometer? Provide the name of the process as well as an explanation of its purpose.
John N.
Why do we need to zero the spectrophotometer before measuring absorbance of a sample?
Madhur L.
A spectrophotometer measures the concentration of a sample dissolved in water by shining a light through it and recording the amount of light that emerges. In other words, if we know the amount of light that is absorbed, we can calculate the concentration of the sample. For a certain substance the concentration (in moles per liter, mol/L) is found by using the formula $$C=-2500 \ln \left(\frac{I}{I_{0}}\right)$$ where $I_{0}$ is the intensity of the incident light and $I$ is the intensity of light that emerges. Find the concentration of the substance if the intensity $I$ is $70 \%$ of $I_{0}$.
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