Prelab Spectrophotometry and Beer's Law uis Cranzaler Name oi30 pm Time м T WRF Write the mathematical expression for Beer's law and explain each symbol in the expression. 1. A-ebc bConcentration Parh lengthincm aosorbonce Molar absorphvity lo g CI/I Use Figure 7.2 to estimate the approximate wavelength of maximum absorption for an aque- ous solution of each of the following: 2. Hemoglobin (the molecule that gives blood its color) a. 670nm b. Chlorophyll (the pigment that gives algae their color) 20nm Fill in the following for the correspondence between % transmittance and absorbance: 3. absorbance 1.00 absorbance = % T 100.0 % T = 0.50 absorbance = absorbance % T 50.0 % T =

Prelab Spectrophotometry and Beer's Law uis Cranzaler Name oi30 pm Time м T WRF Write the mathematical expression for Beer's law and explain each symbol in the expression. 1. A-ebc bConcentration Parh lengthincm aosorbonce Molar absorphvity lo g CI/I Use Figure 7.2 to estimate the approximate wavelength of maximum absorption for an aque- ous solution of each of the following: 2. Hemoglobin (the molecule that gives blood its color) a. 670nm b. Chlorophyll (the pigment that gives algae their color) 20nm Fill in the following for the correspondence between % transmittance and absorbance: 3. absorbance 1.00 absorbance = % T 100.0 % T = 0.50 absorbance = absorbance % T 50.0 % T =

Fundamentals Of Analytical Chemistry

9th Edition

ISBN:9781285640686

Author:Skoog

Publisher:Skoog

Chapter6: Random Errors In Chemical Analysis

Section: Chapter Questions

Problem 6.17QAP

See similar textbooks

Similar questions

3. The following data were obtained at various wavelengths for a 3.6 ´ 10–4 M solution of permanganate in a cell with a path length of 1.00 cm. (Table is in attached) (a) Plot an absorption spectrum for permanganate using these data. (b) From the absorption spectrum obtained, determine the wavelength that permanganate has the strongest absorption. (c) Estimate the molar absorptivity (with proper unit) of permanganate at the absorption maximum. (d) A sample solution containing permanganate gives a %T of 40.0 at the absorption maximum. What is the concentration of permanganate in the sample?
In the development o f an analytical method for the quantitative analysis o f iron using Atomic Absorption spectrophotometry (AAS), a linear calibration curve for standards o f 0.00, 5.00, 10.00, 15.00 and 20.00 ppm was prepared. An iron ore sample with an expected iron content o f 40-60% w/w is to be analysed by this method. An approximately 0.5-g sample is taken, dissolved in a minimum amount o f concentrated HC1 and diluted to 1 L in a volumetric flask using distilled water. A 5.00-mL aliquot is removed with a pipette. With explanation, to what volume (10, 25, 50, 100, 250 500 or 1000 mL) should the 5.00 mL aliquot be diluted, to minimize the uncertainty in the analysis?
Using the absorbance of [FeSCN]+2 at the wavelength of maximum absorption which you obtained in part B, and the diameter of the tube, obtained in part A,calculate the molar extinction coefficient. given info: Concentration of Fe3+ stock solution, C1 = 0.001 M Volume of stock Fe3+ solution pipetted, V1 = 25mL Concentration of diluted stock solution, C2 = 0.0004 M Volume of Fe2+ solution and KSCN (upon mixing) = 10mL Weight of KSCN = 1g The reaction taking place is given as: The reaction taking place is given as: F e 3+ (aq) + SC N − (aq) ⇔Fe [SCN] 2+ (aq) the concentration of [FeSCN]2+ after the mixing of Fe3+ and SCN- is 2.5 x 10-3 M. Moles of [FeSCN]2+ = 2.5 x 10-5 moles Diameter:1.2cm The wavelength at which maximum absorption takes place is = 480 nm
Use the data in Figure 4.8 to estimate the ratio of radiation intensity at 10,000 Å (infrared) to that at 5000 Å (visible) from a blackbody at 5000 K. How will this ratio change with increasing temperature? Explain how this change occurs.
The acid-base indicator HIn undergoes the following reaction in dilute aqueous solution: HIncolor1H++Incolor2 The following absorbance data were obtained for a 5.00 I0-4 M solution of HIn in 0.1 M NaOH and 0.1 M HC1. Measurements were made at wavelengths of 485 nm and 625 nm with 1.00-cm cells. 0.1 M NaOH A485 = 0.075 A625 = 0.904 0.1 M HC1 A485 = 0.487 A625 = 0.181 In the NaOH solution, essentially all of the indicator is present as In-; in the acidic solution, it is essentially all in the form of HIn. (a) Calculate molar absorptivities for In- and HIn at 485 and 625 nm. (b) Calculate the acid dissociation constant for the indicator ¡fa pH 5.00 buffer containing a small amount of the indicator exhibits an absorbance of 0.567 at 485 nm and 0.395 at 625 nm (1.00-cm cells). (c) What is the pH of a solution containing a small amount of the indicator that exhibits an absorbance of0.492 at 485 nm and 0.245 at 635 nm (1.00-cm cells)? (d) A 25.00-mL aliquot of a solution of purified weak organic acid HX required exactly 24.20 mL of a standard solution of a strong base to reach a phenolphthalein end point. When exactly 12.10 mL of the base was added to a second 25.00-mL aliquot of the acid, which contained a small amount of the Indicator under consideration, the absorbance was found to be 0.333 at 485 nm and 0.655 at 625 nm (1.00-cmcells). Calculate the pH of the solution and Ka for the weak acid. (e) What would be the absorbance of a solution at 485 and 625 nm (1.50-cm cells) that was 2.00 10-4 M in the indicator and was buffered to a pH of 6.000?
A solution of Tryptophan has an absorbance at 280 nm of 0.54 in a 0.5 cm length cuvette. Given the absorbance coefficient of trp is 6.4 x 103 Lmol-1cm-1. What is the concentration of solution?
A solution in an absorption cell of path length 2.00 cm transmits 22.1 per cent of light of 372 nm incident upon it. If the concentration of the component is 0.100 mmol/L, what is the molar absorption coefficient at this wavelength? Ans = ____ L mol-1 cm-1.
A (0.002M) Cu2+ solution gave an absorbance of 0.50 at 560 nm in a 1.0 cm cell. The molar absobitivity of solution is equel:
What is the concentration (M) of the following compound as measured in a 1.000 cm cuvette: Molar absorptivity constant: 3525 (M*cm)-1 and Absorption: 0.5334 Hint: Use the Beer law to solve this problem Group of answer choices 1.513E-04 1.513E+04 1.513191E-04 1.513191E+04 1.5E-04
A solution of KMnO4 with a concentration of 8.25 x 10-5 M yields an absorbance value of 0.1302 when measured in a 5.60 cm cuvette, set at a wavelength of 725 nm. Compute for the Molar Absorptivity Coefficient of the sample. Choices: a. 2.8182x10-8 c. 4.8182x10-8 b. 3.8182x10-8 d. 5.8182x10-8
In an analysis of chromium in steel containing 1.76% Cr. 0.5000 g of that steel is weighed and dissolved in acid, whereupon the Cr is oxidized to Cr2O72- (dichromate), and blunt to a volume of 250 mL. A 10 mL aliquot of this solution is diluted with water and acid to a final volume of 100 mL. The resulting solution shows a transmittance of 41.7% in a 1 cm pathlength cell. When a 0.7500 g sample of unknown steel is dissolved in acid, oxidized, and diluted to 250 mL, the resulting solution exhibits a transmittance of 61.3% under identical experimental conditions. What is the percentage of Cr in the steel?