When using a spectrometer to measure the absorbance as a function of concentration, why do we...
When using a spectrometer to measure the absorbance as a function of concentration, why do we have to plot our calibration curve at the maximum wavelength (lambda max)? I know it's to get the highest point of absorbance and therefore ensure high sensitivity, but how does it affect my answers on the calibration curve? what if I didn't use lambda max?
Homework Answers
At 
max, the Absorbance of the Sample is Maximum, i.e. at
max, the Sample absorbs maximum amount of the Incident
Light to give the Optical Density, using Beer-Lambert's Law. If we
don't measure at
max, the corresponding Optical Density (O.D.) will be
low. For a useful Calibration Curve, obeying Lambert-Beer's Law,
the O.D. should be in the Range from 0.1 to 0.7. If we obtain the
Curve at
max, we get the Correct Calibration Curve. But, if we
don't measure at
max for the same set of Solutions, all the O.D. s will
be low(the Slope of the Curve Will be Low), and Consequently the
Calibration Curve will give wrong Information, to obtain the
Concentration of the Unknown Sample.
Add Answer to:
When using a spectrometer to measure the absorbance as
a function of concentration, why do we...
Beer’s Law Objective : We will explore an application of absorption spectroscopy using calibration curves and...
Beer’s Law Objective : We will explore an application of absorption spectroscopy using calibration curves and Beer’s Law. Use the “LAB : HOW TO…” link from the class website if you need help with how to use balance, Bunsen burner… and such. Introduction: You may write this information in your lab notebook for your own reference. It can’t be cut and pasted. Different solutions have different spectral properties. In this portion of the experiment those properties will be utilized to...
III. Standard Curves When we want to determine the concentration of an unknown solution, we typically measure a certain...
III. Standard Curves When we want to determine the concentration of an unknown solution, we typically measure a certain property of standard solutions with our standard (known) solutions and create what's called a standard curve (or calibration curve). A standard curve relates two variables of certain known solutions. That way, when there is an unknown variable for a certain solution, it can be determined through the standard curve. When plotting standard curves, we always plot the independent variable on the...
the guiding questions. the max absorbance is 460. Guiding questions complex turque . Compare the molar...
the
guiding questions. the max absorbance is 460.
Guiding questions complex turque . Compare the molar absorptivity coefficients you obtained with SCN and Fe" as limiting reagents. Would you expect them to be the same? Why or why not? (Week 1) • The accepted molar absorptivity coefficient for FeSCN is 7.0x10' M'cm''. Find the bias and relative bias of your values and suggest possible sources of errors. (Week 1) • Which molar absorptivity coefficient will you use to calculate the...
Table 1. Concentrations of [Fe(Phen),1?, M, in water and UV- vis absorbance values recorded at 2...
Table 1. Concentrations of [Fe(Phen),1?, M, in water and UV- vis absorbance values recorded at 2 -505 nm. Concentration of [Fe(Phen)/, M Absorbance 9.500 x 10 0.999 4.250 x 10 0.480 0.219 2.125 10% 1.063 x 10 0.104 0.000 0.003 Table 2. UV-vis absorbance values of [Fe(phen)]* held at 35 °C after mixing with H SO, and recorded at 5 minute intervals (in water at max = 505 nm). Time (minutes) Absorbance 0.997 0.935 0.877 0.823 0.772 0.724 0.680 0.638...
This is a Biology lab about cellular respiration using mitochondrial suspension. Here's what my hypothesis is:...
This is a Biology lab about cellular respiration using
mitochondrial suspension. Here's what my hypothesis is: An
increased amount of the substrate succinate will increase the rate
of cellular respiration.
I was sure that succinate would increase the rate of the
reaction. But that was not what my graph showed. Here is what was
put into each cuvette
Tube
Buffer
DCIP
Mitochondrial suspension
Succinate (add last)
1
4.4
0.3
0.3
0
2
4.3
0.3
0.3
0.1
3
4.2
0.3
0.3...
What are the Equilibrium voltages of the capacitor and the resistor when the function generator v...
What are the Equilibrium voltages of the capacitor and the
resistor when the function generator voltage is +v0? Is this what
you observe on your oscilloscope sketches?
what are the equilibrium voltages of the capacitor and the resistor when the function generator voltage is ± you observe on your oscilloscope sketches? ? Is this what An RC circuit consists of a resistor connected to a capacitor. There may also be a fixed power supply, depending on whether the capacitor is...
Procedure 1. Label four 50.0 mL volumetric flasks.)! through 4 2. Using a buret, add 10.00 ml of ...
Procedure 1. Label four 50.0 mL volumetric flasks.)! through 4 2. Using a buret, add 10.00 ml of 2.00x10'MFeNO)D solution to each of the flasks 3. Using a buret, add 1.00 mL. 2.00 mL, 3.00 mL, and 4.00 mL of 2.00x 10 MKSCN 4. Fill each flask to the mark with 0.10 M HNO, solution. Stopper each flask and invert 5. Measure the absorbance of each solution at a wavelength of 447 nm (the absorbance reterred to in step 1...
How do I make a line of best fit (regression) with the following data? I am...
How do I make a line of best fit (regression) with the
following data? I am aware of how to make it in Microsoft Excel,
but I am having trouble figuring out how to find my x value for
making the graph. Y value is absorbance, what do I use for x value
to calculate the slope?
Tube 0.5 mM sulfide standard (ml) Sulfide amount (umol) Sulfide reagent (ml) 0.0 4.9 0.11 0.00 0.2 FeCl3 dH2O to Absorbance 10ml total...
Based on this data, I find it hard to the calculations and analysis and discussion Beer's...
Based on this data, I find it hard to the calculations and analysis
and discussion
Beer's Law Calculations: A. Dilution Calculations 1. Use the actual mass of cobalt(II) nitrate hexahydrate you used to calculate the concentration of your stock solution. 2. Calculate the concentration of your diluted solutions. The easiest way to do this is with the equation MiV2-M2V2. Show the work for the calculation of the concentration of at least one of your dilute solutions. 3. Make a table...
please correct me If I did anything wrong. im very confused on this. • Determining k...
please correct me If I did anything wrong. im very confused on
this.
• Determining k in Beer's Law 2. Determining the equilibrium constant Test Tube No. Absorbance Test Tube No. Absorbance 0,060 이79 0.253 0319 0.400 0.120 0.268 0.361 0.461 0.695 Post Laboratory Questions 1. Complete the following table and calculate k-value for the Beer's Law. All concentrations should be in M. [Fe(SCN)2) Absorbance CA Test Tube No. Diluted Fe(NO3)2 (mL) 0 . 2 3 4 s Reference 1.0...
III. Standard Curves When we want to determine the concentration of an unknown solution, we typically measure a certain property of standard solutions with our standard (known) solutions and create what's called a standard curve (or calibration curve). A standard curve relates two variables of certain known solutions. That way, when there is an unknown variable for a certain solution, it can be determined through the standard curve. When plotting standard curves, we always plot the independent variable on the...
the
guiding questions. the max absorbance is 460.
Guiding questions complex turque . Compare the molar absorptivity coefficients you obtained with SCN and Fe" as limiting reagents. Would you expect them to be the same? Why or why not? (Week 1) • The accepted molar absorptivity coefficient for FeSCN is 7.0x10' M'cm''. Find the bias and relative bias of your values and suggest possible sources of errors. (Week 1) • Which molar absorptivity coefficient will you use to calculate the...
Table 1. Concentrations of [Fe(Phen),1?, M, in water and UV- vis absorbance values recorded at 2 -505 nm. Concentration of [Fe(Phen)/, M Absorbance 9.500 x 10 0.999 4.250 x 10 0.480 0.219 2.125 10% 1.063 x 10 0.104 0.000 0.003 Table 2. UV-vis absorbance values of [Fe(phen)]* held at 35 °C after mixing with H SO, and recorded at 5 minute intervals (in water at max = 505 nm). Time (minutes) Absorbance 0.997 0.935 0.877 0.823 0.772 0.724 0.680 0.638...
This is a Biology lab about cellular respiration using
mitochondrial suspension. Here's what my hypothesis is: An
increased amount of the substrate succinate will increase the rate
of cellular respiration.
I was sure that succinate would increase the rate of the
reaction. But that was not what my graph showed. Here is what was
put into each cuvette
Tube
Buffer
DCIP
Mitochondrial suspension
Succinate (add last)
1
4.4
0.3
0.3
0
2
4.3
0.3
0.3
0.1
3
4.2
0.3
0.3...
What are the Equilibrium voltages of the capacitor and the
resistor when the function generator voltage is +v0? Is this what
you observe on your oscilloscope sketches?
what are the equilibrium voltages of the capacitor and the resistor when the function generator voltage is ± you observe on your oscilloscope sketches? ? Is this what An RC circuit consists of a resistor connected to a capacitor. There may also be a fixed power supply, depending on whether the capacitor is...
Procedure 1. Label four 50.0 mL volumetric flasks.)! through 4 2. Using a buret, add 10.00 ml of 2.00x10'MFeNO)D solution to each of the flasks 3. Using a buret, add 1.00 mL. 2.00 mL, 3.00 mL, and 4.00 mL of 2.00x 10 MKSCN 4. Fill each flask to the mark with 0.10 M HNO, solution. Stopper each flask and invert 5. Measure the absorbance of each solution at a wavelength of 447 nm (the absorbance reterred to in step 1...
How do I make a line of best fit (regression) with the
following data? I am aware of how to make it in Microsoft Excel,
but I am having trouble figuring out how to find my x value for
making the graph. Y value is absorbance, what do I use for x value
to calculate the slope?
Tube 0.5 mM sulfide standard (ml) Sulfide amount (umol) Sulfide reagent (ml) 0.0 4.9 0.11 0.00 0.2 FeCl3 dH2O to Absorbance 10ml total...
Based on this data, I find it hard to the calculations and analysis
and discussion
Beer's Law Calculations: A. Dilution Calculations 1. Use the actual mass of cobalt(II) nitrate hexahydrate you used to calculate the concentration of your stock solution. 2. Calculate the concentration of your diluted solutions. The easiest way to do this is with the equation MiV2-M2V2. Show the work for the calculation of the concentration of at least one of your dilute solutions. 3. Make a table...
please correct me If I did anything wrong. im very confused on
this.
• Determining k in Beer's Law 2. Determining the equilibrium constant Test Tube No. Absorbance Test Tube No. Absorbance 0,060 이79 0.253 0319 0.400 0.120 0.268 0.361 0.461 0.695 Post Laboratory Questions 1. Complete the following table and calculate k-value for the Beer's Law. All concentrations should be in M. [Fe(SCN)2) Absorbance CA Test Tube No. Diluted Fe(NO3)2 (mL) 0 . 2 3 4 s Reference 1.0...
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