In a lab, dissociation constant, K, of an acid-base indicator is measured. A 1.00 x 104 M solution of the indicator buffered at pH 6.00 shows an absorbance of 0.26 at 520 nm in a 1.00-cm cuvette. Given the acidic form of this indicator has a molar absorptivity of 5000 and its basic form has a molar absorptivity of 150O L cm1 mol1, K, is found to be

In a lab, dissociation constant, K, of an acid-base indicator is measured. A 1.00 x 104 M solution of the indicator buffered at pH 6.00 shows an absorbance of 0.26 at 520 nm in a 1.00-cm cuvette. Given the acidic form of this indicator has a molar absorptivity of 5000 and its basic form has a molar absorptivity of 150O L cm1 mol1, K, is found to be

Fundamentals Of Analytical Chemistry

9th Edition

ISBN:9781285640686

Author:Skoog

Publisher:Skoog

Chapter14: Principles Of Neutralization Titrations

Section: Chapter Questions

Problem 14.9QAP

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b) In the development of a method for the determination of formic acid by neutralization volumetry, the pH was calculated as a function of the addition of NaOH for the titration of 25.00 mL of 0.1280 mol/L formic acid with NaOH standardized with concentration of 0.0670 mol/L. With reference to this titration curve, determine the pH of the solution after the addition of 5.00 mL of titrant and at the equivalence point. Data: Ka=1.70x10-4. Present the results with two places after the comma and show your calculations. c) Based on the table below, indicate which indicators could be used to determine the end point of this titration.
A 250.0mg sample of an organic monoprotic weak acid was dissolved in an appropriate solvent and titrated with 0.091M NAOH , requiring 29.5ml to reach end point. Determine equivalent weight
A microbiologist is preparing a medium on which to cultureE. colibacteria. She buffers the medium at pH 7.00 to minimize the effect of acid-producing fermentation. What volumes ofequimolar aqueous solutions of K₂HPO₄and KH₂PO₄must shecombine to make 100. mL of the pH 7.00 buffer?
The Ka values for nitrous acid (HNO2) and hypochlorous (HClO) acid are 4.5 x10-4and 3.0 x10-8, respectively. Which one would be more suitable for use in asolution buffered at pH = 7.0? What other substances would be needed to makethe buffer?
A 0.4071-g sample of CaCO3 (MM: 100.09 g/mole) is transferred to a 500-mL volumetric flask, dissolved using a minimum of 6 M HCl, and diluted to volume. A 50.00-mL aliqout of this solution was mixed with 5 mL of a pH 10 NH3-NH4Cl buffer that contains a small amount of Mg2+--EDTA to adjust the pH to 10. After adding calmagite as an indicator, the solution is titrated with the EDTA, requiring 42.63 mL to reach the end point. Report the molar concentration of EDTA in the titrant. 9.543 x 10-3 M 5.748 x 10-3 M 3.266 x 10-4 M 1.018 x 10-4 M
1. Sketch the labelled pH curve for a reaction between 10.0 mL of 1.00 mol/L strong base with 1.00mol/L strong acid. Ensure that your sketch has a title and properly labeled axis. 2. During a titration with an acidic titrant, the endpoint is found to occur at a pH of 5.5. Choose anappropriate indicator and predict the colour change.
a) At temperature 25°C, 0.02 M hydrazine, N2H4 solution is 0.69% ionised. Calculate the i. Concentration of OH- ion ii. ionisation constant, Kb b) Calculate the mass of sodium benzoate, C6H5COONa that should be added to 500 mL of 0.2M aqueous benzoic acid, C6H5COOH solution to produce a buffer with pH 3.50?[ Ka for C6H5COOH = 6.3 x10-5] c) When a 1 x 10-3 moldm-3 solution of CaCl2 is mixed with an equal volume of a 1 x 10-3 moldm-3 solution of Na2SO4, will precipitate form? (Ksp CaSO4= 2 x 10-5) Do you mean that pH? That was all the given information the question gave.. I don't understand how to use the ionised part the most
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10. 50 cm3 of 0.05 M weak acid solution is titrated with 0.1 M NaOH solution. The measured pH valuesare 7.345 and 7.497 at the consumptions of 6.0 and 6.1 cm3, respectively. What value of the buffer capacity can be calculated in the solution at pH = 7.421?11. Based on the data given in question 10, what is the total concentration of the anion of the weak acid atthe given point?
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