3. Pyridine is a weak base with a Kb 1.7 x 109. If 0.300 moles of pyridine is added to 1.00 L o water, what will be the equilibrium concentrations of the species below: [Pyridine] = а. [Pyridine-H'] (the pyridinium ion) b. [OH-= С.

3. Pyridine is a weak base with a Kb 1.7 x 109. If 0.300 moles of pyridine is added to 1.00 L o water, what will be the equilibrium concentrations of the species below: [Pyridine] = а. [Pyridine-H'] (the pyridinium ion) b. [OH-= С.

Chemistry by OpenStax (2015-05-04)

1st Edition

ISBN:9781938168390

Author:Klaus Theopold, Richard H Langley, Paul Flowers, William R. Robinson, Mark Blaser

Publisher:Klaus Theopold, Richard H Langley, Paul Flowers, William R. Robinson, Mark Blaser

Chapter15: Equilibria Of Other Reaction Classes

Section: Chapter Questions

Problem 76E: Write the Lewis structures of the reactants and product of each of the following equations, and...

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Consider a solution prepared by mixing a weak acid HA. HCl, and NaA. Which of the following statements best describes what happens? a. The H+ from the HCl reacts completely with the A from the NaA. Then the HA dissociates somewhat. b. The H+ from the HCl reacts somewhat with the A from the NaA to make HA, while the HA is dissociating. Eventually you have equal amounts of everything. c. The H+ from the HCl reacts somewhat with the A from the NaA to make HA while the HA is dissociating. Eventually all the reactions have equal rates. d. The H+ from the HCl reacts completely with the A from the NaA. Then the HA dissociates somewhat until too much H+ and A are formed, so the H+ and A react to form HA, and so on. Eventually equilibrium is reached. Justify your choice, and for choices you did not pick, explain what is wrong with them.
For oxyacids, how does acid strength depend on a. the strength of the bond to the acidic hydrogen atom? b. the electronegativity of the element bonded to the oxygen atom that bears the acidic hydrogen? c. the number of oxygen atoms? How does the strength of a conjugate base depend on these factors? What type of solution forms when a nonmetal oxide dissolves in water? Give an example of such an oxide. What type of solution forms when a metal oxide dissolves in water? Give an example of such an oxide.
The ion HTe- is an amphiprotic species; it can act as either an acid or a base.. (a) What is Ka for the acid reaction of HTe- with H2O?. (b) What is Kb, for the reaction in which HTe- functions as a base in water?. (c) Demonstrate whether or not the second ionization of H2Te can be neglected in the calculation of [HTe-] in a 0.10 M solution of H2Te.
What is a salt? List some anions that behave as weak bases in water. List some anions that have no basic properties in water. List some cations that behave as weak acids in water. List some cations that have no acidic properties in water. Using these lists, give some formulas for salts that have only weak base properties in water. What strategy would you use to solve for the pH of these basic salt solutions? Identify some salts that have only weak acid properties in water. What strategy would you use to solve for the pH of these acidic salt solutions? Identify some salts that have no acidic or basic properties in water (produce neutral solutions). When a salt contains both a weak acid ion and a weak base ion, how do you predict whether the solution pH is acidic, basic, or neutral?
Strong Acids, Weak Acids, and pH Two 0.10-mol samples of the hypothetical monoprotic acids HA(aq) and HB(aq) are used to prepare 1.0-L stock solutions of each acid. a Write the chemical reactions for these acids in water. What are the concentrations of the two acid solutions? b One of these acids is a strong acid, and one is weak. What could you measure that would tell you which acid was strong and which was weak? c Say that the HA(aq) solution has a pH of 3.7. Is this the stronger of the two acids? How did you arrive at your answer? d What is the concentration of A(aq) in the HA solution described in part c? e If HB(aq) is a strong acid, what is the hydronium-ion concentration? f In the solution of HB(aq), which of the following would you expect to be in the greatest concentration: H3O+(aq), B(aq), HB(aq), or OH(aq)? How did you decide? g In the solution of HA(aq), which of the following would you expect to be in the greatest concentration: H3O+(aq), A+(aq), HA(aq), or OH(aq)? How did you decide? h Say you add 1.0 L of pure water to a solution of HB. Would this water addition make the solution more acidic, make it less acidic, or not change the acidity of the original solution? Be sure to fully justify your answer. i You prepare a 1.0-L solution of HA. You then take a 200-mL sample of this solution and place it into a separate container. Would this 200 mL sample be more acidic, be less acidic, or have the same acidity as the original 1.0-L solution of HA(aq)? Be sure to support your answer.
Ionization of the first proton from H2SO4 is complete (H2SO4 is a strong acid); the acid-ionization constant for the second proton is 1.1 102. a What would be the approximate hydronium-ion concentration in 0.100 M H2SO4 if ionization of the second proton were ignored? b The ionization of the second proton must be considered for a more exact answer, however. Calculate the hydronium-ion concentration in 0.100 M H2SO4, accounting for the ionization of both protons.
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Calculate the pH of a solution prepared by mixing 49.0 mL of butyric acid, HC4H7O2, with 6.15 g of KOH in water. The following data about butyric acid may be helpful: density=0.9595g/mL;K a =1.54105
Each box represents an acid solution at equilibrium. Squares represent H+ ions. Circles represent anions. (Although the anions have different identities in each figure, they are all represented as circles.) Water molecules are not shown. Assume that all solutions have the same volume. (a) Which figure represents the strongest acid? (b) Which figure represents the acid with the smallest Ka? (c) Which figure represents the acid with the lowest pH?
You have a solution of the weak acid HA and add some HCl to it. What are the major species in the solution? What do you need to know to calculate the pH of the solution, and how would you use this information? How does the pH of the solution of just the HA compare with that of the final mixture? Explain.
. The concepts of acid-base equilibria were developed in this chapter for aqueous solutions (in aqueous solutions, water is the solvent and is intimately involved in the equilibria). However, the Brønsted-Lowry acid-base theory can be extended easily to other solvents. One such solvent that has been investigated in depth is liquid ammonia. NH3. a. Write a chemical equation indicating how HCl behaves as an acid in liquid ammonia. b. Write a chemical equation indicating how OH- behaves as a base in liquid ammonia.
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.)