The pKa of CH3COOH is 4.8 and the pKa of HCOOH is 3.8. Given this information, one knows that HCOO- is a weaker base than CH3COO- CH3COOH reacts with HO- while HCOOH does not HCOOH is a weaker acid than CH3COOH HCOOH reacts with HO- while CH3COOH does not CH3COOH completely ionizes in water

16-27 Guanidine, p/Ca 13.6, is a very strong base, almost as basic as hydroxide ion. NH NH2+ II II H2N—C—NH2 + H2O H2N—C—NH2 + OH" Guanidine Guanidinium ion pKb = 13.6 Complete the Lewis structure for guanidine, showing all valence electrons. The remarkable basicity of guanidine is attributed to the fact that the positive charge on the guanidinium ion is delocalized by resonance over the three nitrogen atoms. This delocalization increases the stability of the guanidinium ion relative to the ammonium ion or substituted ammonium ions. Draw three equivalent contributing structures for the guanidinium ion and show by the use of curved arrows how these three contributors are related. Propose an explanation for the fact that protonation occurs on the C=NH nitrogen rather than on one of the —NH., nitrogens. (Hint: Consider the resonance stabilization of the structure formed by protonation on a —NH., nitrogen compared with the resonance stabilization of the structure formed by protonation on the =NH nitrogen.) Predict the N—C—N bond angles in the hybrid. Which is the stronger acid, the ammonium ion or the guanidinium ion?

In each pair, select the stronger acid. (a) Pyruvic acid (pKa 2.49) or lactic acid (pKa 3.08) (b) Citric acid (pKa1 3.08) or phosphoric acid (pKa1 2.10)

Which of the following common food additives gives a basic solution when dissolved in water? (a) NaNO3 (used as a meat preservative) (b) NaC6H5CO2(Sodium benzoate, used as a soft drink preservative) (c) NaH2PO4(used as a emulsifier in the manufacture of pasteurized cheese)

. Write the conjugate acid for each of the following bases. a. ClO- b. Cl- c. ClO3 d. ClO4

Glycolic acid, HOCH2CO2H, is the simplest member of a group of compounds called αhydroxy acids, ingredients in skin care products that have an OH group on the carbon adjacent to a CO2H group. Would you expect HOCH2CO2H to be a stronger or weaker acid than acetic acid, CH3CO2H?

Identify the base in the following equation:   H2O  +  H2CO3  ↔  H3O+  +  HCO3-

HF, CH3CH2CH2OH, CH3CH2COOH which is the strongest to weakest acid? Provide a reason as to why.

The K, of formic acid is 1.8 x 104, the K, of acetic acid is 1.8 x 105 and the K, of hypobromous acid is 2.8 x 10⁹. Which of the following statements is true? The weakest conjugate base is acetate The weakest conjugate base is formate The weakest conjugate base is hypobromite Formic acid is a strong acid Hypobromous acid is a base

Another way to express acid strength is by using pk b:pK a =−logK a Another way to express base strength is by using pK b pK b =−logK b A new potential heart medicine, code-named X-281, is being tested by a pharmaceutical company, Pharma-pill. As a research technician at Pharma-pill, you are told that X-281 is a monoprotic weak acid, but because of security concerns, the actual chemical formula must remain top secret. The company is interested in the drug's K a value because only the dissociated form of the chemical is active in preventing cholesterol buildup in arteries.To find the pK a of X-281, you prepare a 0.079 M M test solution of X-281 at 25.0 ∘ C The pH of the solution is determined to be 3.00. What is the pK a of X-281?