14-E. An ammonia gas-sensing electrode gave the following cali-bration points when all solutions contained 1 M NaOH.NH3 (M)E (mV)NH3 (M)E (mV)1.00 x 10-55.00 x 101.00 x 105.00 x 103268.0368.05-35.00 X 10310.0386.41.00 X 10-4326.8427.6A dry food sample weighing 312.4 mg was digested by the Kjeldahlprocedure (Section 10-8) to convert all nitrogen into NH. Thedigestion solution was diluted to 1.00 L, and 20.0 mL were transferred to a 100-mL volumetric flask. The 20.0-mL aliquot was treated with10.0 mL of 10.0M NaOH plus enough Nal to complex the Hg cat-alyst from the digestion and diluted to 100.0 mL. When measuredwith the ammonia electrode, this solution gave a reading of 339.3 mV.Calculate the wt% nitrogen in the food sample.

For a gas-sensing electrode, EMF versus log (Concentration) is a straight-line curve.

Answered: o a 100-mL volumetric flask. The…

Fundamentals Of Analytical Chemistry

9th Edition

ISBN:9781285640686

Author:Skoog

Publisher:Skoog

Chapter17: Complexation And Precipitation Reactions And Titrations

Section: Chapter Questions

Problem 17.17QAP

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Given: You weigh out exactly 0.200 g of Fe(NH4)2(SO4)2·6H2O and dissolve it in the 100.00 mL volumetric flask. You then pipette 2.00 mL of this solution into the 50.00 mL volumetric flask to prepare the stock standard tris-bipyridyl-iron(II) solution. a. Calculate the molar concentration of iron(II) in this solution in the 50.00 mL volumetric flask. (The MW of Fe(NH4)2(SO4)2·6H2O is 392.14 g/mol) (answer a given the information above)
In a beaker 20mL of 0.5M Ca(OH)2 and 80mL of 0.5M CH3COOH are mixed and then this mixture is added on 2g of active coal. After waiting for about 20 minutes the solution is filtered and the filter is titrated by 1M NaOH solution in the presence of an indicator. 10mL of the NaOH solution has been used. Calculate the amount of acetic acid adsorbed per gram of the coal in moles. Explain all the steps and reactions of the experimental process by your own comments.
One method for determining whether an individual recently fired a gun is to look for traces of antimony in residue collected from the individual’s hands. Anodic stripping voltammetry at a mercury film electrode is ideally suited for this analysis. In a typical analysis a sample is collected from a suspect using a cotton-tipped swab wetted with 5% v/v HNO3. After returning to the lab, the swab is placed in a vial that contains 5.0 mL of 4 M HCl that is 0.02 M in hydrazine sulfate. After soaking the swab, a 4.0-mL portion of the solution is transferred to an electrochemical cell along with 100 μL of 0.01 M HgCl2. After depositing the thin film of mercury and the antimony, the stripping step gives a peak current of 0.38 μA. After adding a standard addition of 100 μL of 00×102 ppb Sb, the peak current increases to 1.14 μA. How many nanograms of Sb were collected from the suspect’s hand?
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You have been asked to determine the empirical formula of an iron(?) nitrate salt, Fe(NO). You weigh out 4.1419 g of a solid iron(?) nitrate sample and dissolve it with DI-HO while filling to the calibration mark of a 250.00 mL volumetric flask. You then use an ion-selective electrode to determine the iron ion concentration, which gives a reading of 3910 mg Fe^7+/L . Calculate the empirical formula of your iron(?) nitrate sample. (Hint-Assume that the remaining percent of ions in solution are nitrate ions.)
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A 5.00 mL tap water sample was measured out with a volumetric pipette, and added to a 25 mL Erlenmeyer flask. It was then titrated with a 0.0100 M Na2EDTA.2H2O solution, and found to take 0.635 mL of the EDTA solution to reach the blue endpoint.
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