Some weak acids and their conjugate bases Acid (Proton Donor) Conjugate Base (Proton Acceptor) pKa Ką (M) НСООН HCOO +H+ 3.75 1.78 x 10-4 Formic acid Formate ion CH3COOH Acetic acid CH;CO0 Acetate ion +H* 4.76 1.74 x 10-5 OH OH +H* 3.86 1.38 x 10-4 CH3CH-COO CH3CH-COOH Lactic acid Lactate ion H;PO4 Phosphoric acid H,PO, Dihydrogen phosphate ion +H+ 2.14 7.24 x 10-3 H,PO, Dihydrogen phosphate ion HPO,?- Monohydrogen phosphate ion +H* 6.86 1.38 x 10-7 HPO2- Monohydrogen phosphate ion PO, +H+ 12.4 3.98 x 10-13 Phosphate ion H2CO3 Carbonic acid HCO3 Bicarbonate ion +H* 6.3* 5.1 x 10-7* HCO3 Bicarbonate ion co2- Carbonate ion +H* 10.25 5.62 x 10-11 C6H5OH Phenol +H+ 9.89 1.29 x 10-10 Phenolate ion NH4 NH3 +H+ 9.25 5.62 x 10-10 Ammonium ion Ammonia 1 1 1 1 111

Some weak acids and their conjugate bases Acid (Proton Donor) Conjugate Base (Proton Acceptor) pKa Ką (M) НСООН HCOO +H+ 3.75 1.78 x 10-4 Formic acid Formate ion CH3COOH Acetic acid CH;CO0 Acetate ion +H* 4.76 1.74 x 10-5 OH OH +H* 3.86 1.38 x 10-4 CH3CH-COO CH3CH-COOH Lactic acid Lactate ion H;PO4 Phosphoric acid H,PO, Dihydrogen phosphate ion +H+ 2.14 7.24 x 10-3 H,PO, Dihydrogen phosphate ion HPO,?- Monohydrogen phosphate ion +H* 6.86 1.38 x 10-7 HPO2- Monohydrogen phosphate ion PO, +H+ 12.4 3.98 x 10-13 Phosphate ion H2CO3 Carbonic acid HCO3 Bicarbonate ion +H* 6.3* 5.1 x 10-7* HCO3 Bicarbonate ion co2- Carbonate ion +H* 10.25 5.62 x 10-11 C6H5OH Phenol +H+ 9.89 1.29 x 10-10 Phenolate ion NH4 NH3 +H+ 9.25 5.62 x 10-10 Ammonium ion Ammonia 1 1 1 1 111

Introductory Chemistry For Today

8th Edition

ISBN:9781285644561

Author:Seager

Publisher:Seager

Chapter9: Acids, Bases, And Salts

Section: Chapter Questions

Problem 9.84E

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Similar questions

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8-60 How is the buffer capacity affected by the ratio of the conjugate base to the conjugate acid?
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8-112 Consider an initial 0.040 M hypobromous acid (HOBr) solution at a certain temperature. At equilibrium after partial dissociation, its pH is found to be 5.05. What is the acid ionization constant, Ka, for hypobromous acid at this temperature?
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For conjugate acidbase pairs, how are Ka and Kb related? Consider the reaction of acetic acid in water CH3CO2H(aq)+H2O(l)CH3CO2(aq)+H3O+(aq) where Ka = 1.8 105 a. Which two bases are competing for the proton? b. Which is the stronger base? c. In light of your answer to part b. why do we classify the acetate ion (CH3CO2) as a weak base? Use an appropriate reaction to justify your answer. In general, as base strength increases, conjugate acid strength decreases. Explain why the conjugate acid of the weak base NH3 is a weak acid. To summarize, the conjugate base of a weak acid is a weak base and the conjugate acid of a weak base is a weak acid (weak gives you weak). Assuming Ka for a monoprotic strong acid is 1 106, calculate Kb for the conjugate base of this strong acid. Why do conjugate bases of strong acids have no basic properties in water? List the conjugate bases of the six common strong acids. To tie it all together, some instructors have students think of Li+, K+, Rb+, Cs+, Ca2+, Sr2+, and Ba2+ as the conjugate acids of the strong bases LiOH, KOH. RbOH, CsOH, Ca(OH)2, Sr(OH)2, and Ba(OH)2. Although not technically correct, the conjugate acid strength of these cations is similar to the conjugate base strength of the strong acids. That is, these cations have no acidic properties in water; similarly, the conjugate bases of strong acids have no basic properties (strong gives you worthless). Fill in the blanks with the correct response. The conjugate base of a weak acid is a_____base. The conjugate acid of a weak base is a_____acid. The conjugate base of a strong acid is a_____base. The conjugate acid of a strong base is a_____ acid. (Hint: Weak gives you weak and strong gives you worthless.)