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The Beer-Lambert Law:


A = epsilon*b*c


A is absorbance (unitless)

epsilon is the extinction coefficient at a particular wavelength (L cm-1 mol-1)

b is the path length of the cuvette (cm)

c is the concentration of the solution (mol/L)

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How can you calculate absorbance of unknown from linear equation?

To calculate the absorbance of an unknown sample using a linear equation, you first need to establish a calibration curve by plotting the absorbance values of known standards against their concentrations. The resulting linear equation, typically in the form (y = mx + b), relates absorbance (y) to concentration (x), where (m) is the slope and (b) is the y-intercept. By measuring the absorbance of the unknown sample and substituting this value into the linear equation, you can solve for the concentration of the unknown sample. This allows you to determine the absorbance based on its concentration derived from the calibration curve.


What are the units of absorbance?

Absorbance is a dimensionless quantity and has no units. It is calculated using the formula A = log10(I0/I), where A is absorbance, I0 is the intensity of the incident light, and I is the intensity of the transmitted light. Since it is a logarithmic ratio of two intensities, absorbance is expressed simply as a number, typically ranging from 0 to 3 for most applications.


What is maximum absorbance of methyle orange at 242 nm?

The maximum absorbance of methyl orange typically occurs at around 464 nm, not 242 nm. At 242 nm, the absorbance may be lower or not significant, as this wavelength is outside the main absorption range for methyl orange. For accurate absorbance values, it is important to refer to specific absorption spectra or experimental data for methyl orange.


Is it possible to calculate the chromacity coordinates using absorbance values?

Yes, it is possible to calculate the chromaticity coordinates using absorbance values. The best way to calculate the chromaticity coordinates using absorbance values is by using the formula x = x/x+y+z.


Why should a graph of absorbance versus concentration go through the origin?

A graph of absorbance versus concentration should pass through the origin because, according to Beer-Lambert Law, absorbance is directly proportional to concentration. When the concentration of a solution is zero, there are no absorbing species present, resulting in zero absorbance. This linear relationship indicates that as concentration increases, absorbance increases proportionally, reinforcing that the graph should start at the origin (0,0). Any deviation from this could indicate issues such as instrument calibration errors or scattering effects.

Related Questions

Is there a simple equation to calculate the concentration given the absorbance and a time?

You need a graphic concentration versus absorbance.


How can you calculate absorbance of unknown from linear equation?

To calculate the absorbance of an unknown sample using a linear equation, you first need to establish a calibration curve by plotting the absorbance values of known standards against their concentrations. The resulting linear equation, typically in the form (y = mx + b), relates absorbance (y) to concentration (x), where (m) is the slope and (b) is the y-intercept. By measuring the absorbance of the unknown sample and substituting this value into the linear equation, you can solve for the concentration of the unknown sample. This allows you to determine the absorbance based on its concentration derived from the calibration curve.


Is wavelength or absorbance the dependent variable?

"absorbance"Since in the experiment, you probably choose the wavelength, then measure the absorbance (absorption?, the absorbance is the dependent variable.


What is the purpose of the blank?

Blank Sample in Spectrophotometry is used to measure the absorbance of light without sample. It is subtracted from the total absorbance for measurement of Absorbance from a sample's absorbance.


Is it possible to calculate the molar extinction coefficient from a single absorbance measurement on one solution of known concentration?

Yes, it is possible to calculate the molar extinction coefficient (ε) from a single absorbance measurement if you have a solution of known concentration. According to Beer-Lambert Law, the relationship is given by A = εcl, where A is the absorbance, c is the concentration, and l is the path length of the cuvette. Rearranging this equation, you can derive ε by using the formula ε = A / (cl), provided you know the absorbance, concentration, and path length.


What is difference between specific absorbance and absorbance interms of spectroscopy?

specific absorbance- it is absorbance in a solution containing one gm of substance in 100 ml solvent in 1cm shell. so it is having a difference with absorbance which is negative logarithm of incident light to the transmitted light. divya.chakraborty@gmail.com


Is absorbance considered a discrete or continuous variable?

Absorbance is considered a continuous variable.


What is the different between primary absorbance and secondary absorbance in fluorescence?

in primary light absorbed by outer molecule while in secondary re-absorbance occurs


What is the specific absorbance of aspirin?

If you have a spectrofotometer ( the thing to mesure the absorbance) then play with the setting and use a maximum. this will lay close to your specific absorbance or take the pharmacopea or a MERCK index


The absorbance of a solution of NiCl2 of unknown concentration is found to be 0.388 what is the concentration of this soultion?

The concentration of the NiCl2 solution can be determined by using Beer's Law, which states that absorbance is directly proportional to concentration. You would need to know the molar absorptivity of NiCl2 at that specific wavelength in order to calculate the concentration. Plugging in the values of absorbance and molar absorptivity into Beer's Law equation would give you the concentration of the NiCl2 solution.


What is the abbreviation for Absorbance?

A


What is baseline in uv?

In UV spectroscopy, the baseline refers to the horizontal line at zero absorbance on the absorbance axis. It represents the reference point for measuring the absorbance of the sample. The baseline should be stable and noise-free to ensure accurate measurement of the absorbance of the sample.