Grams of diprotic acidInitial buret reading of NaOH(aq)Final buret reading of NaOH(aq)Volume of added NaOH(aq)Molarity of NaOH(aQ)1 mL. = 1cm³NaOH(aq) + H2A(aq) -----→ NazA(aq) + H2O(1)0.1482 g0.00 mL.19.50 mL.0.1029 MCalculate molar mass of H2A(aq) acid.Hint:Moles of NaOH(aq) :-→ moles of H2A(aq) ----------> molar mass of H2A(aq) in g/ mole Chem. 1A:Acid-Base titration : to determine molar mass of a diprotic ACID : H2APut a weighing paper on the pan of balance and tare it. Then add 0.1482 g of an unknowndiprotic acid. Transfer the acid to a Erlenmeyer flask add 35.0 mL. water and 4 dropsphenophethaleine. The color of solution is colorless.Set up a 50.00 mL. buret: wash the buret with tap water twice, with deionized water twice andand the 0.1029 M NAOH(aq). Fill the buret with 0.1029 M NaOH(aq), remove the air bubbleand adjust the initial buret reading to 0.00 mL.Put the Erlenmeyer flask containing the acid and the phenolphethaleine below the buret with0.1029 M NAOH(aq). Add NaOH(aq) from buret to the Erlenmeyer flask containing the diproticacid and phenolphethaleine , until the color of the solution turn to pink by adding one or twodrops of NaOH(aq). Then stop adding NaOH(aq) from buret and read the final volume ofNaOH(aq).Acid-base titration:buretbase of knownconcentration+ stopcockacid of unknownconcentrationReading the final buret reading of NaOH(aq):19.62 cm1919.50 cm'2019.42 cmThe following data table has been obtained

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Grams of diprotic acid Initial buret reading of NaOH(aq) Final buret reading of NaOH(aq) Volume of added NaOH(aq) Molarity of NaOH(aQ) 1 mL. = 1cm³ NaOH(aq) + H2A(aq) -------→ Na2A(aq) + H2O(1) 0.1482 g 0.00 mL. 19.50 mL. 0.1029 M Calculate molar mass of H2A(aq) acid. Hint: Moles of NaOH(aq) ----------> moles of H2A(aq) - -→ molar mass of H2A(aq) in g/ mole

Grams of diprotic acid Initial buret reading of NaOH(aq) Final buret reading of NaOH(aq) Volume of added NaOH(aq) Molarity of NaOH(aQ) 1 mL. = 1cm³ NaOH(aq) + H2A(aq) -------→ Na2A(aq) + H2O(1) 0.1482 g 0.00 mL. 19.50 mL. 0.1029 M Calculate molar mass of H2A(aq) acid. Hint: Moles of NaOH(aq) ----------> moles of H2A(aq) - -→ molar mass of H2A(aq) in g/ mole

Chemistry: Principles and Reactions

8th Edition

ISBN:9781305079373

Author:William L. Masterton, Cecile N. Hurley

Publisher:William L. Masterton, Cecile N. Hurley

Chapter14: Equilibria In Acid-base Solutions

Section: Chapter Questions

Problem 50QAP: Morphine, C17H19O3N, is a weak base (K b =7.4107). Consider its titration with hydrochloric acid. In...

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Sketch the titration curve for a weak acid titrated by a strong base. When performing calculations concerning weak acidstrong base titrations, the general two-slep procedure is to solve a stoichiometry problem first, then to solve an equilibrium problem to determine the pH. What reaction takes place in the stoichiometry part of the problem? What is assumed about this reaction? At the various points in your titration curve, list the major species present after the strong base (NaOH, for example) reacts to completion with the weak acid, HA. What equilibrium problem would you solve at the various points in your titration curve to calculate the pH? Why is pH 7.0 at the equivalence point of a weak acid-strong base titration? Does the pH at the halfway point to equivalence have to be less than 7.0? What does the pH at the halfway point equal? Compare and contrast the titration curves for a strong acidstrong base titration and a weak acidstrong base titration.
A bottle of concentrated hydroiodic acid is 57% HI by weight and has a density of 1.70 g/mL. A solution of this strong and corrosive acid is made by adding exactly 10.0 mL to some water and diluting to 250.0 mL. If the information on the label is correct, what volume of 0.988 M NaOH is needed to neutralize the HI solution? Suggest an indicator for the titration.
A 25.0-mL sample of hydroxylamine is titrated to the equivalence point with 35.8 mL of 0.150 M HCl. a What was the concentration of the original hydroxylamine solution? b What is the pH at the equivalence point? c Which indicators, bromphenol blue, methyl red, or phenolphthalein, should be used to detect the end point of the titration? Why?
A friend asks the following: Consider a buffered solution made up of the weak acid HA and its salt NaA. If a strong base like NaOH is added, the HA reacts with the OH to form A. Thus the amount of acid (HA) is decreased, and the amount of base (A) is increased. Analogously, adding HCI to the buffered solution forms more of the acid (HA) by reacting with the base (A). Thus how can we claim that a buffered solution resists changes in the pH of the solution? How would you explain buffering to this friend?
Morphine, C17H19O3N, is a weak base (K b =7.4107). Consider its titration with hydrochloric acid. In the titration, 50.0 mL of a 0.1500 M solution of morphine is titrated with 0.1045 M HCl. (a) Write a balanced net ionic equation for the reaction that takes place during titration. (b) What are the species present at the equivalence point? (c) What volume of hydrochloric acid is required to reach the equivalence point? (d) What is the pH of the solution before any HCl is added? (e) What is the pH of the solution halfway to the equivalence point? (f) What is the pH of the solution at the equivalence point?
A buffer is prepared in which the ratio [ H2PO4 ]/[ HPO42 ]is 3.0. (a) What is the pH of this buffer? (b) Enough strong acid is added to convert 15% of HPO42- to H2PO4-. What is the pH of the resulting solution? (c) Enough strong base is added to make the pH 7.00. What is the ratio of [H2PO4-] to [HPO42-] at this point?
8-93 Do a 1.0 M CH3COOH solution and a 1.0 M HCI solution require the same amount of 1.0 M NaOH to hit a titration end point? Explain.
A student intends to titrate a solution of a weak monoprotic acid with a sodium hydroxide solution but reverses the two solutions and places the weak acid solution in the buret. After 23.75 mL of the weak acid solution has been added to 50.0 mL of the 0.100 M NaOH solution, the pH of the resulting solution is 10.50. Calculate the original concentration of the solution of weak acid.
You are given the following acidbase titration data, where each point on the graph represents the pH after adding a given volume of titrant (the substance being added during the titration). a What substance is being titrated, a strong acid, strong base, weak acid, or weak base? b What is the pH at the equivalence point of the tiration? c What indicator might you use to perform this titration? Explain.
Consider the nanoscale-level representations for Question 111 of the titration of the aqueous strong acid HA with aqueous NaOH, the titrant. Water molecules and Na+ ions are omitted for clarity. Which diagram corresponds to the situation: (a) After a very small volume of titrant has been added to the initial HA solution? (b) Halfway to the equivalence point? (c) When enough titrant has been added to take the solution just past the equivalence point? (d) At the equivalence point? Nanoscale representations for Question 111.
When 40.00 mL of a weak monoprotic acid solution is titrated with 0.100-M NaOH, the equivalence point is reached when 35.00 mL base has been added. After 20.00 mL NaOH solution has been added, the titration mixture has a pH of 5.75. Calculate the ionization constant of the acid.
A diprotic acid, H2B(MM=126g/moL), is determined to be a hydrate, H2B xH2O. A 10.00-g sample of this hydrate is dissolved in enough water to make 150.0 mL of solution. Twenty-five milliliters of this solution requires 48.5 mL of 0.425 M NaOH to reach the equivalence point. What is x?