An analytical chemist weighs out 0.085 g of an unknown monoprotic acid into a 250 mL volumetric flask and dilutes to the mark with distilled water. She then titrates this solution with 0.1900 M NaOH solution. When the titration reaches the equivalence point, the chemist finds she has added 5.2 mL of NaOH solution. Calculate the molar mass of the unknown acid. Be sure your answer has the correct number of significant digits.

An analytical chemist weighs out 0.085 g of an unknown monoprotic acid into a 250 mL volumetric flask and dilutes to the mark with distilled water. She then titrates this solution with 0.1900 M NaOH solution. When the titration reaches the equivalence point, the chemist finds she has added 5.2 mL of NaOH solution. Calculate the molar mass of the unknown acid. Be sure your answer has the correct number of significant digits.

Chemistry

9th Edition

ISBN:9781133611097

Author:Steven S. Zumdahl

Publisher:Steven S. Zumdahl

Chapter15: Acid-base Equilibria

Section: Chapter Questions

Problem 14Q: Consider the following four titrations. i. 100.0 mL of 0.10 M HCl titrated by 0.10 M NaOH ii. 100.0...

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Consider the following four titrations. i. 100.0 mL of 0.10 M HCl titrated by 0.10 M NaOH ii. 100.0 mL of 0.10 M NaOH titrated by 0.10 M HCl iii. 100.0 mL of 0.10 M CH3NH2 titrated by 0.10 M HCl iv. 100.0 mL of 0.10 M HF titrated by 0.10 M NaOH Rank the titrations in order of: a. increasing volume of titrant added to reach the equivalence point. b. increasing pH initially before any titrant has been added. c. increasing pH at the halfway point in equivalence. d. increasing pH at the equivalence point. How would the rankings change if C5H5N replaced CH3NH2 and if HOC6H5 replaced HF?
Aniline hydrochloride, (C6H5NH3)Cl, is a weak acid. (Its conjugate base is the weak base aniline, C6H5NH2.) The acid can be titrated with a strong base such as NaOH. C6H5NH3+(aq)+OH(aq)C6H5NH2(aq)+H2O(l) Assume 50.0 mL of 0.100 M aniline hydrochloride is titrated with 0.185 M NaOH. (Ka for aniline hydrochloride is 2.4 105.) (a) What is the pH of the (C6H5NH3) solution before the titration begins? (b) What is the pH at the equivalence point? (c) What is the pH at the halfway point of the titration? (d) Which indicator in Figure 17.11 could be used to detect the equivalence point? (e) Calculate the pH of the solution after adding 10.0, 20.0, and 30.0 mL of base. (f) Combine the information in parts (a), (b), (c), and (e), and plot an approximate titration curve.
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The weak monoprotic acid, acetic acid, is titrated with the strong base, potassium hydroxide as follows: HC2H3O2(aq) + K+ OH- (aq) → K+ C2H3O2-(aq) + H2O(l) Ka for acetic acid is 1.81 x 10-5 (at 25 oC). A 25.00 mL sample of a solution of acetic acid with concentration 0.0833 M is titrated with 0.1000 M KOH. A. What is the pH at the beginning of the titration, Vbase = 0.00 mL? B. What is the pH at the equivalence point? C. What is the pH of the titration when 5.00 mL of base have been added? D. What is the pH when the volume of base added equals half the volume of the equivalence point? E. What is the pH of the titration when 20.00 mL of base have been added? F. What is the pH of the titration when 30.00 mL of base have been added?
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Benzoic acid, C6H5COOH, dissociates in water as shown in the equation below. A 40.0 mL sample of an aqueous solution of benzoic acid with a concentration of 0.50 M is titrated using standardized 0.25 M NaOH. C6H5COOH(s) -> C6H5COO–(aq) + H+(aq) Ka = 6.46 x 10^-5 Calculate the pH of the solution after the following amounts of NaOH have been added… A. 0 mL B. 10 mL C. 85 mL
In the course of various qualitative analysis procedures, the following mixtures are encountered: Cr(OH)3 and Fe(OH)3 . Suggest how each mixture might be separated.
A 25 mL solution of 0.255 M AgNO3 titrant was added to a 50 mL sample that contains chromate ion (CrO4 2-). It required 12.39 mL of a 0.1998 M thiocyanate (SCN- ) solution to titrate to a red point. What is the concentration of the chromate ion in ppm and molarity?
For a titration to be effective, the reaction must be rapid and the yield of the reaction must essentially be 100%. Is Kc > 1, < 1, or ≈ 1 for a titration reaction?
Potassium hydrogen phthalate (KHPKHP) is often used as a primary standard in acid–base titrations. If 20.05 mL NaOH20.05 mL NaOH is required to neutralize 0.397 g KHP,0.397 g KHP, what is the concentration of the NaOH?