An analytical chemist weighs out 0.045 g of an unknown diprotic acid into a 250 mL volumetric flask and dilutes to the mark with distilled water. She then titrates this solution with 0.1800 M NaOH solution. When the titration reaches the equivalence point, the chemist finds she has added 4.2 mL of NaOH solution. Calculate the molar mass of the unknown acid. Be sure your answer has the correct number of significant digits. g mol

An analytical chemist weighs out 0.045 g of an unknown diprotic acid into a 250 mL volumetric flask and dilutes to the mark with distilled water. She then titrates this solution with 0.1800 M NaOH solution. When the titration reaches the equivalence point, the chemist finds she has added 4.2 mL of NaOH solution. Calculate the molar mass of the unknown acid. Be sure your answer has the correct number of significant digits. g mol

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 65QAP: Follow the directions of Question 64. Consider two beakers: Beaker A has a weak acid(K a=1105)....

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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.
Phenol, C6H5OH, is a weak organic acid. Suppose 0.515 g of the compound is dissolved in enough water to make 125 mL of solution. The resulting solution is titrated with 0.123 M NaOH. C6H5OH(aq) + OH(aq) C6H5O(aq) + H2O() (a) What is the pH of the original solution of phenol? (b) What are the concentrations of all of the following ions at the equivalence point: Na+, H3O+, OH, and C6H5O? (c) What is the pH of the solution at the equivalence point?
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?
Follow the directions of Question 64. Consider two beakers: Beaker A has a weak acid(K a=1105). Beaker B has HCI. The volume and molarity of each acid in the beakers are the same. Both acids are to be titrated with a 0.1 M solution of NaOH. (a) Before titration starts (at zero time), the pH of the solution in Beaker A is the pH of the solution in Beaker B. (b) At half-neutralization (halfway to the equivalence point), the pH of the solution in Beaker A the pH of the solution in Beaker B. (c) When each solution has reached its equivalence point, the pH of the solution in Beaker A the pH of the solution in Beaker B. (d) At the equivalence point, the volume of NaOH used to titrate HCI in Beaker B the volume of NaOH used to titrate the weak acid in Beaker A.
A monoprotic organic acid that has a molar mass of 176.1 g/mol is synthesized. Unfortunately, the acid produced is not completely pure. In addition, it is not soluble in water. A chemist weighs a 1.8451-g sample of the impure acid and adds it to 100.0 mL of 0.1050 M NaOH. The acid is soluble in the NaOH solution and reacts to consume most of the NaOH. The amount of excess NaOH is determined by titration: It takes 3.28 mL of 0.0970 M HCl to neutralize the excess NaOH. What is the purity of the original acid, in percent?
Consider all acid-base indicators discussed in this chapter. Which of these indicators would be suitable for the titration of each of these? (a) NaOH with HClO4 (b) acetic acid with KOH (c) NH3 solution with HBr (d) KOH with HNO3 Explain your choices.
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.
A 2.500-g sample of a mixture of sodium carbonate and sodium chloride is dissolved in 25.00 mL of 0.798 M HCl. Some acid remains after the treatment of the sample. a Write the net ionic equation for the complete reaction of sodium carbonate with hydrochloric acid b If 28.7 mL of 0.108 M NaOH were required to titrate the excess hydrochloric acid, how many moles of sodium carbonate were present in the original sample? c What is the percent composition of the original sample?
A solution made up of 1.0 M NH3 and 0.50 M (NH4)2SO4 has a pH of 9.26. a Write the net ionic equation that represents the reaction of this solution with a strong acid. b Write the net ionic equation that represents the reaction of this solution with a strong base. c To 100. mL of this solution, 10.0 mL of 1.00 M HCl is added. How many moles of NH3 and NH4+ are present in the reaction system before and after the addition of the HCl? What is the pH of the resulting solution? d Why did the pH change only slightly upon the addition of HCl?
Three students titrate different samples of the same solution of HCI to obtain its molarity. Below are their data. Student A: 20.00mLHCl+20.00mLH2O 0.100 M NaOH used to titrate to the equivalence point Student B: 20.00mLHCl+40.00mLH2O 0.100 M NaOH used to titrate to the equivalence point Student C: 20.00mLHCl+20.00mLH2O 0.100 M Ba(OH)2 used to titrate to the equivalence point. All the students calculated the molarities correctly. Which (if any) of the following statements are true? (a) The molarity calculated by A is half that calculated by B. (b) The molarity calculated by A is equal to that calculated by C. (c) The molarity calculated by B is twice that calculated by C. (d) The molarity calculated by A is twice that calculated by B. (e) The molarity calculated by A is equal to that calculated by B.
Consider the nanoscale-level representations for Question 110 of the titration of the aqueous weak acid HX with aqueous NaOH, the titrant. Water molecules and Na+ ions are omitted for clarity. Which diagram corresponds to the situation: After a very small volume of titrant has been added to the initial HX solution? When enough titrant has been added to take the solution just past the equivalence point? Halfway to the equivalence point? At the equivalence point? Nanoscale representations for Question 110.