The absorbance of a cationic iron(II) sample solution was measured in a spectrophotometer, but the instrument returned an error because the absorbance was too high. The sample was then diluted by using a pipette to take 100.0 µL of the sample and injecting it into a cuvette already containing 2.00 mL of water (total volume is 2.00 mL + 100.0 µL). The absorbance value of the diluted solution corresponded to a concentration of 8.57x10-6 M.What was the concentration of the original solution? Express the concentration to three significant figures with the appropriate units. • View Available Hint(s) µA ? original concentration of Fe²+ = Value Units Submit

The absorbance of a cationic iron(II) sample solution was measured in a spectrophotometer, but the instrument returned an error because the absorbance was too high. The sample was then diluted by using a pipette to take 100.0 µL of the sample and injecting it into a cuvette already containing 2.00 mL of water (total volume is 2.00 mL + 100.0 µL). The absorbance value of the diluted solution corresponded to a concentration of 8.57x10-6 M.What was the concentration of the original solution? Express the concentration to three significant figures with the appropriate units. • View Available Hint(s) µA ? original concentration of Fe²+ = Value Units Submit

Fundamentals Of Analytical Chemistry

9th Edition

ISBN:9781285640686

Author:Skoog

Publisher:Skoog

Chapter27: Molecular Fluorescence Spectroscopy

Section: Chapter Questions

Problem 27.9QAP

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The absorbance of a cationic iron(II) sample solution was measured in a spectrophotometer, but the instrument returned an error because the absorbance was too high. The sample was then diluted by using a pipette to take 100.0 μLμL of the sample and injecting it into a cuvette already containing 2.00 mLmL of water (total volume is 2.00 mLmL + 100.0 μLμL). The absorbance value of the diluted solution corresponded to a concentration of 7.71×10−6 M M . What was the concentration of the original solution? Express the concentration to three significant figures with the appropriate units.
To determine the molar concentration of a metal ion in a solution of unknown concentration, a student fırst made five standard solutions that contain the metal ion of interest and measured the absorbance of each solution in a spectrophotometer at its Amax- A calibration curve was obtained that had an equation of y = 5.747 x + 0.013 Next, the student pipetted 15.0 mL of the initial solution of unknown concentration into a 100.0 mL volumetric flask, and filled the flask with deionized water to the line. The absorbance of this final diluted solution was found to be A = 0.226 at Amax. The color of the original and diluted solution was blue. What is the molarity of the original solution, as well as an approximate Amax for this metal ion? 2max = 599 nm and concentration is 0.247 M Amax 457 nm and concentration is 0.247 M %3D 2 max = 457 nm and concentration is 0.0371 M 1 max 599 nm and concentration is 0.0371 M Amax = 599 nm and concentration is 0.00557 M
Part A In order to understand how this equation is derived and why it holds true, the product of each side of the equation should be examined. What value and unit do you get when you multiply a concentration of 0.897 M by a volume of 0.700 L ? This question can be expressed as 0.700 L 0.897 mol 1 Express your answer to three significant figures with the appropriate units. • View Available Hint(s) HA ? M¡V1 = Value Units Submit Part B When you need to produce a variety of diluted solutions of a solute, you can dilute a series of stock solutions. A stock solution has a significantly higher concentration of the given solute (typically 10' to 104 times higher than those of the diluted solutions). The high concentration allows many diluted solutions to be prepared using minimal amounts of the stock solution. What volume of a 6.51 M stock solution do you need to prepare 100. mL of a 0.2949 M solution of HCl? Express the volume to three significant figures with the appropriate units. • View…
The absorbance of a cationic iron(II) sample solution was measured in a spectrophotometer, but the instrument returned an error because the absorbance was too high. The sample was then diluted by using a pipette to take 100.0 μL�L of the sample and injecting it into a cuvette already containing 2.00 mLmL of water (total volume is 2.00 mLmL + 100.0 μL�L). The absorbance value of the diluted solution corresponded to a concentration of 6.22×10−6 M � . What was the concentration of the original solution?
You begin preparation of the calibration curve to measure absorbance vs concentration of FeSCN2+. To do so, you add 2.422 mL of 0.200 M Fe(NO3)3 to a cuvette and then directly add 215 µL of 0.001 M KSCN. What is the resulting concentration of FeSCN2*, assuming complete conversion of SCN' to FeSCN2+? Enter your answer in units of mM to four digits after the decimal.
A student prepared four standard solutions of (NH4)2Fe(SO4)2 and measured their absorbance at 505 nm. She created a calibration plot with the best-fit line of y = 9372 x + 0.0539. She measured the absorbance of her diluted unknown sample solution as (4.69x10^-1) nm. If she prepared her diluted sample solution by diluting 10.00 mL of the original solution to a total volume of 50.00 mL with deionized water, what is the concentration of Fe2+ in her original solution? Answer in units of M. Note: Your answer is assumed to be reduced to the highest power possible.
What are the differences between systematic and random errors and how do they effect accuracy and precision? In what circumstances would you use standard addition (versus a normal calibration curve) to determine the amount of an analyte in a sample? A urine sample, containing analyte Z is analysed by the standard addition method where 5 mL of the original sample was mixed with increasing amounts of a Z standard and each solution diluted to a volume of 50 mL prior to analysis. A plot of the final concentration of the standard in each of the 50 mL samples (x axis) versus The measured signal from the analysis of each 50 mL sample (on y axis) produced a straight line with the general equation: y = 44.72x + 4.06 what was the final concentration of Z in the 50 mL standard addition sample? what was the initial concentration of Z in the original urine sample?
A 10.00 mL of natural water sample containing Ni2+ was pipetted into a volumetric flask and diluted to 50.00 mL with pure water. In the second 10.00 mL of natural water sample transferred into a volumetric flask, exactly 4.00 mL of a Ni2+ solution with a concentration of 5.99 mg/L was added and then diluted to 50.00 mL with pure water. The measured absorbance is A1= 0.436 and A2 = 0.663. What is the Ni2+ concentration in unit of mg/L in the natural water sample?
(a) For use in an iodine titration, you prepare a solution from 0.222 2 (+0.000 2) g of KIO3 [FM 214.001 0 (+0.000 9)] in 50.00 (+0.05) mL. Find the molarity and its uncertainty with an appropriate number of significant figures. (b) Would your answer be affected significantly if the reagent were only 99.9% pure?
From the following data, calculate the concentration of the analyte in the sample read at 700 nm: Absorbance of unknown sample = 0.807 Absorbance of a 130 mg/dl standard = 0.234 Do not answer in image format. Maintain accuracy and quality in your answer. Answer completely.
Ben ran through the experiment and found the best-fit line listed below for his standard calibration curve of absorbance vs concentration in M. y = 3214.0x + 0.0076 Ben then prepared a solution that had 5.00 mL 0.002 M iron(III) nitrate in 1 M nitric acid, 3.00 mL 0.002 M potassium thiocyanate, and 2.00 mL DI water. If the absorbance for the solution was 0.436, calculate the equilibrium concentration of iron(III) thiocyanate in the solution. Report your answer in mM with three places after the decimal.
professor Scimemi has accepted you as a Master’s student and you are involved in a project that studies the cellular basis of neuropsychiatric diseases. For your electrophysiology recordings you have to make a recording solution containing (in mM): 119 NaCl, 2.5 KCl, 2.5 CaCl2, 1 MgCl2, 26.2 NaHCO3, 1 NaH2PO4, 22 glucose. You need 800 ml of it. How much KCl do you need to weigh out? Hint: we only care about KCl here. (MW KCl is 74.55 g/mol