Why do we use the wavelength of maximum absorbance?

Higher absorption of the wavelength provides higher sensitivity; thus, it is desirable to select a wavelength with maximum absorption… Here, the absorption spectrum comes in. See the spectrum below. This is an iron solution to which a coloring reagent was added.

What are the advantages of selecting the wavelength of maximum absorption for determining absorbance values for preparation of a Beer’s Law plot?

For each spectrum, the absorbance value is determined at a particular wavelength. Generally, it is best to select a wavelength where the absorbance is at a maximum, since this will minimize the relative error of the measurement. A plot of absorbance vs. concentration (a Beer’s Law plot) can then be prepared.

Is the max absorbance a good wavelength to take readings?

But to have an accurate and reproducible reading you should choose a wavelength with maximum absorbance. So you should avoid wavelengths where there are absorption peaks. I suggest choosing the wavelength that changes most during your experiment.

Why is it important to set the wavelength of the spectrophotometer for measuring the absorbance of the solutions?

It is important to “blank” the spectrophotometer before taking an absorption measurement of a sample at each new wavelength, because the water and cuvette also absorb light, so the spectrophotometer won’t measure the absorption of water and cuvette.

Does wavelength affect absorbance?

One important consideration is the wavelength of radiation to use for the measurement. Remember that the higher the molar absorptivity, the higher the absorbance. What this also means is that the higher the molar absorptivity, the lower the concentration of species that still gives a measurable absorbance value.

How does lambda max affect absorbance?

There is no ‘relationship’ between Lambda Max and Absorbance. Concentration (mass/mL) is related to Absorbance by the Beer-Lambert law (A=abc).

How does wavelength affect absorbance?

The longer the path length, the more molecules there are in the path of the beam of radiation, therefore the absorbance goes up. As you likely know from other experiences, a particular chemical species absorbs some wavelengths of radiation and not others.

Why is it important to determine the wavelength of maximum absorbance for the crystal violet solution?

The first step in this analysis will be to determine the wavelength of maximum absorbance for crystal violet and the corresponding molar absorption coefficient at that wavelength. This wavelength will be used to monitor the disappearance of crystal violet throughout the course of the experiment.

Does higher wavelength mean more absorbance?

A wavelength longer than the peak absorbance and shorter than the peak absorbance will result in more light being recorded by the detector. You can determine peak absorbance by taking several readings of the same sample and varying the wavelength of the spectrophotometer.

Why do we need to set the wavelength of a spectrophotometer?

When using a a spectrophotometer to measure concentration changes in a colored solution you want to select the wavelength at which the greatest absorbance by the solution occurs. When we see a substance as a particular color, we’re seeing the wavelengths or colors of light that it reflects.

Why is wavelength important in spectrophotometric measurements?

You need a spectrometer to produce a variety of wavelengths because different compounds absorb best at different wavelengths. For example, p-nitrophenol (acid form) has the maximum absorbance at approximately 320 nm and p-nitrophenolate (basic form) absorb best at 400nm, as shown in Figure 3.

How does wavelength and absorbance relate?

and at each wavelength, the absorbance of the purple solution is exactly equal to the sum of the absorbances of the red and blue solutions at that wavelength. This can be seen clearly by looking at all three spectra at a wavelength of 525 nm.