1 / 20

Acids & Bases

Acids & Bases. Part 2. Acid & Base Ionization Constants. A weak acid or base produces a reaction that only partially goes forward. The acid or base ionization constant measures the degree of ionization (or the strength) The smaller the Ka, the weaker the acid

gaston
Download Presentation

Acids & Bases

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Acids & Bases Part 2

  2. Acid & Base Ionization Constants • A weak acid or base produces a reaction that only partially goes forward. • The acid or base ionization constant measures the degree of ionization (or the strength) • The smaller the Ka, the weaker the acid • The smaller the Kb, the weaker the base • Keq = [products] [reactants] • 1 x 10 -14 = Ka x Kb

  3. Acid & Base Ionization Constants • Write the Ka expressions for the following reactions: • HClO2 + H2O  H3O+ + ClO2- • HIO + H2O  H3O+ + lO-

  4. Acid & Base Ionization Constants • Write the Kb expression for CH3NH2

  5. Common Ka Values(You may need this for some of the homework problems!)

  6. Using pH to Calculate Ka • Suppose you measure the pH of a 0.100 M solution of HCOOH (formic acid) and found it to be 2.38. Calculate the Ka.

  7. Using pH to Calculate Ka HCOOH + H2O  COOH- + H3O+

  8. Using pH to Calculate Ka • Calculate the Ka of a 0.220 M solution of H3AsO4 with a pH of 1.50. Calculate the pKa

  9. % Ionization • A 0.10 M solution of a weak acid (HX) is 17.5% ionized. Calculate Ka.

  10. % Ionization • HX + H20  X- + H30+

  11. Another Example • A sample of a weak acid HX has a pH of 3.5. If the Ka = 2.7 x 10 -5, calculate the initial concentration of HX.

  12. Another Example • HX + H20  X- + H30+

  13. More Examples • What is the pH of a 25 ml sample of 0.25 M HC2H3O2? Ka = 1.8 x 10 -5 • pH = 2.676

  14. Example • What is the % dissociation of a 0.325 M solution of HCOOH? Ka = 1.8 x 10 -4

  15. Weak Mixtures • Calculate the pH of a solution that contains 1.00 M HCN & 5.00 M HNO2. Also calculate the [CN-] at equilibrium. KaHCN = 6.2 x 10 -10 & KaHNO2 = 4.0 x 10 -4

  16. HNO2 H+ + NO2- Weak Mixtures

  17. Part 2 of question… Also calculate the [CN-] at equilibrium. HCN  H+ + CN- Weak Mixtures

  18. Another example • What is the pH when 25 ml of 0.25 M HNO3 is mixed with 25 ml of 0.25 M HNO2 (Ka HNO2 = 4.0 x 10-4)

  19. Example • What is the pH of a 0.25 M solution of NH3. KbNH3 = 1.8 x 10-5

  20. One more example • What is the pH of a mixture of 25 ml of a 0.25M KOH solution & 25 ml of 0.25 M CH3NH2?

More Related