Benzoic acid is a weak acid that has antimicrobial properties. Its sodium salt, sodium benzoate, is a preservative found in foods, medications, and personal hygiene products. Benzoic acid dissociates in water: C6H5COOH(aq) + H₂O(1) C6H5COO- (aq) + H3O+ (aq) The pK₂ of this reaction is 4.2. In a 0.66 mol L¹ solution of benzoic acid, what percentage of the molecules are ionized?

Benzoic acid is a weak acid that has antimicrobial properties. Its sodium salt, sodium benzoate, is a preservative found in foods, medications, and personal hygiene products. Benzoic acid dissociates in water: C6H5COOH(aq) + H₂O(1) C6H5COO- (aq) + H3O+ (aq) The pK₂ of this reaction is 4.2. In a 0.66 mol L¹ solution of benzoic acid, what percentage of the molecules are ionized?

Introduction to General, Organic and Biochemistry

11th Edition

ISBN:9781285869759

Author:Frederick A. Bettelheim, William H. Brown, Mary K. Campbell, Shawn O. Farrell, Omar Torres

Publisher:Frederick A. Bettelheim, William H. Brown, Mary K. Campbell, Shawn O. Farrell, Omar Torres

Chapter19: Carboxylic Anhydrides, Esters, And Amides

Section: Chapter Questions

Problem 19.44P

See similar textbooks

Similar questions

4 (Chemical Connections 19F) Why do Lactomer stitches dissolve within 2 to 3 weeks following surgery?
Lactic acid, CH3CH(OH)COOH, is a weak monoprotic acid with a melting point of 53 C. It exists as two enantiomers (Sec. 7-2f) that have slightly different Ka values. The D form has a Ka of 1.5 104 and the L form has a Ka of 1.6 104. The D form is synthesized by some bacteria. The L form is produced in muscle cells during anaerobic metabolism in which glucose molecules are broken down into lactic acid and molecules of adenosine triphosphate (ATP) are formed. When lactic acid builds up too rapidly in muscle tissue, severe pain results. (a) Which form of lactic acid (D or L) is the stronger acid? Explain your answer. (b) Determine the pKa that would be measured for a 50:50 mixture of the two forms of lactic acid in aqueous solution, pKa = log Ka (c) A solution of D-lactic acid is prepared. Use HL as a general formula for lactic acid, and write the equation for the ionization of lactic acid in water. (d) If 0.100-M solutions of these two acids (D and L) were prepared, calculate what the pH of each solution would be. (e) Before any lactic acid dissolves in the water, what reaction determines the pH? (f) Calculate the pH of a solution made by dissolving 4.46 g D-lactic acid in 500. mL of water. (g) Calculate the volume (mL) of 1.15-M NaOH(aq) required to completely neutralize 4.46 g of pure lactic acid. (h) Calculate the pH of the solution when exactly enough NaOH was added to neutralize all of the lactic acid for (i) the D form; (ii) the L form; and (iii) a 50:50 mixture of the two forms.
The pkb of methylamine, CH3NH2, is 3.36. Calculate the pka of its conjugate acid, CH3NH3*. pka =
Ammonia (NH3) is a weak base that under acidic conditions becomes protonated to the ammonium ion in thefollowing reaction:NH3 + H+ → NH4 +NH3 freely permeates biological membranes, including thoseof lysosomes. The lysosome is a subcellular organelle witha pH of about 4.5–5.0; the pH of cytoplasm is about 7.0.What is the effect on the pH of the fluid content of lysosomes when cells are exposed to ammonia? Note: Ammonium (NH4 +) does not diffuse freely across membranes.
(a) Explain how NaBH, in CH;OH can reduce hemiacetal A to 1,4-butanediol (HOCH,CH,CH,CH,OH). (b) What product is formed when A is treated with Ph;P=CHCH,CH(CH),? (c) The drug isotretinoin is formed by reaction of X and Y. What is the structure of isotretinoin? Although isotretinoin (trade name Accutane or Roaccutane) is used for the treatment of severe acne, it is dispensed under strict controls because it also causes birth defects. PPha NaOCH,CH3 HO- isotretinoin HO A Br X Y
The structure of the amino acid tyrosine is shown below in its completely protonated form. PK 16 OH CH2O : ד pK₂ 2 PK 9 H₂N C-C-OH H
но HO но он The pK, of ascorbic acid (vitamin C) is 4.17, showing that it is slightly more acidic than acetic acid (CH3CO0H, pKa 4.74). (a) Show the fou r different conjugate bases that would be formed by deprotonation of the four different OH groups in ascorbic acid. (b) Compare the stabilities of these four conjugate bases, and predict which OH group of ascorbic acid is the most acidic. (c) Compare the most stable conjugate base of ascorbic acid with the conjugate base of acetic acid, and suggest why these two compounds have similar acidities, even though ascorbic acid lacks the carboxylic acid (COOH) group.
For an acid with a pKa of 5.00, what is the pKb of its conjugate base?
Write equations for the following acid-base reactions. Label the conjugate acids and bases, and show any inductive stabilization. Predict whether the equilibrium favors the reactants or products. Try to do this without using a table of pKa values, (a) CH3CH2OH + CH3NH- (b) F3CCOONa + Br3C¬COOH(c) CH3OH + H2SO4 (d) NaOH + H2S(e) CH3NH3+ + CH3O- (f) BrCH2CH2OH + F3C¬CH2O-(g) NaOCH2CH3 + Cl2CHCH2OH (h) H2Se + NaNH2(i) CH3CHFCOOH + FCH2CH2COO- (j) CF3CH2O- + FCH2CH2OH
(a) Given that Ka for acetic acid is 1.8 x 10-5 and that forhypochlorous acid is 3.0 x 10-8, which is the stronger acid?(b) Which is the stronger base, the acetate ion or the hypochloriteion? (c) Calculate Kb values for CH3COO- and ClO-.
What is the pKa of benzoic acid? What is the molar concentration of sodium benzoate (conjugate base)? What is the molar concentration of benzoic acid (weak acid)?
Provide an explanation without using the pka values : Why is phenol stronger acid than butanoic acid?