Pre-lab 5 - Beer's law

A. Copper sulfate pentahydrate is often used to teach students about Beer’s Law by making a standard curve (linear regression). The bright blue color of the solution has a peak absorbance in the red range of the electromagnetic spectrum. The absorbance value is proportional to concentration. How many grams of CuSO4 5H2O to make up 250 mL of a 0.2 M stock of this solution? B. Using M1V1 = M2V2 how many mL would a student need to measure out in graduated cylinder to make up a 50 mL (V2) solution of 0.1M, 0.05 M, 0.025M 0.0125M solutions for a standard curve at the peak wavelenth for this compound?

A. Copper sulfate pentahydrate is often used to teach students about Beer’s Law by making a standard curve (linear regression). The bright blue color of the solution has a peak absorbance in the red range of the electromagnetic spectrum. The absorbance value is proportional to concentration. How many grams of CuSO4 5H2O to make up 250 mL of a 0.2 M stock of this solution? B. Using M1V1 = M2V2 how many mL would a student need to measure out in graduated cylinder to make up a 50 mL (V2) solution of 0.1M, 0.05 M, 0.025M 0.0125M solutions for a standard curve at the peak wavelenth for this compound? I need help with part B of this question.

A direct ELISA experiment was done to determine the amount of protein present in a sample. A standard curve was prepared by plotting log Absorbance versus log concentration of protein in (ng/mL). The equation of the line is Y= 0.895 X -1.25. If an unknown protein shows an absorbance of 1.23. Calculate the concentration of this protein in the sample in (ng/mL).

If a solution has an absorbance of 2 you can be certain that  the solution is highly diluted and needs to be concentrated  all the statements are correct  this is a reliable absorbance and downstream analysis can be done  the solution is highly concentrated and needs dilution

23. How do you set up and solve absorbance problems like this?

Can you help me on questions 2 AND 3

GMU QUESTION 7 An ethanol solution of 3.5 mg/100 ml of compound Y (150.0 g/mol) in a 1.00 cm quartz cell has an absorbance (A) of 0.972 at Amax-235 nm. What is its molar extinction coefficient? Report your answer to the correct number of significant figures. Do not include units in your answer.OGMU 2020

Table II Cuvette # Concentration Absorbance 0.50 M 1 1.049 2 0.40 M 0.926 3 0.20 M 0.740 0.298 4 0.10 M 5 0.05 M 0.202 Unknown # 9 0.427 Unknown # 10 7 0.646 Blank (DI water) 0 1. If Beer's Law is valid, the value of "E" should be constant. Use A = E*C*L or E= A/(E*L) and the data from Table II to calculate values of E for the five solutions below The value of L is normally 1 cm so E = A/C in this experiment. Table III Solution # Calculated Values of E 1 2 3 4 5

AP Questions // Questions 10 - 11) A student creates four solutions with varying concentration of FeSCN2 and gathers the following data at 298 K using a spectrophotometer calibrated to 460 nm: [FESCN] Absorbance 1.1 x 10-4 M 0.076 1.6 x 10-4 M 0.112 2.2 x 10-4 M 0.167 2.5 x 10-4 M 0.199 On the axis below, create a Beer's Law calibration plot for [FESCN2*]. Draw a best-fit line through your data points.

25. How would you set up and solve concentration problems like this which involve absorbance?

How would I do 2? the concentration iron is 1.85mg/vitamin tablet, and the absorbance at 508nm is 0.37

Using the following data, if an unknown solution of Orange Dye X had a measured absorbance of 0.345, what is the concentration Orange Dye X in the solution?  Concentration (mM)  Absorbance 0.005 0.143 0.010 0.285 0.015 0.428 0.020 0.570

Given the following standard curve of Absorbance vs Concentration (mM), what in the concentration of Aspirin if the absorbance is 0.822?

Conclusion 5: You are tasked with analyzing a suspiciously pink sample of drinking water to establish if it has unsavory levels of MnO4-contamination. It has an absorbance of 0.83 at 544 nm when measured in a cuvette that is 1 cm across. Using the equation of your trend line from Plot 4, determine the concentration of KMnO4 in moles/liter. Convert this concentration to grams of manganese/liter and compare it to the EPA guideline above.       Trandline is Absorbtion = 2000(Concentration KMnO4) (Y=Mx)

A series of six solutions was prepared at the given concentrations. Sample AB C D E F Concentration (mM) 50 100 | 150 | 200 300 400 The absorbance of each solution was then measured using a colorimeter. Sample A B C D E F Absorbance 0.25 0.50 0.75 1.00 1.50 2.00 What is the concentration of the solution with an absorbance of 1.50? C = mM

4. An ethanol solution of p-aminosalicylic acid has a molar absorptivity of 1.6 x 10ʻL mol"cm at a wavelength of 284 nm. Calculate the absorbance of a 4.8 x 10°M solution in a 1.000 cm cuvette at this wavelength.

Chemistry Question

Absorbance 1.40 Beer's Law Plot 1.20 1.00 0.80 0.60 0.40 0.20 0.00 0 10 20 30 40 50 Concentration (M x 105) D The slope for the line is 80.23. Use the Beer's Law plot provided to determine the concentration for a solution with absorbance = 0.5786. M