1 / 17

Chapter 15

Chapter 15. Acids and Bases Suroviec Spring 2014. I. Definitions of Acids/Bases. Arrhenius Acid: something that releases H + in water Base: something that releases OH - in water. Br ø nsted-Lowry Acid: substance that donates a proton Base: substance that accepts a proton.

gizi
Télécharger la présentation

Chapter 15

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. Chapter 15 Acids and Bases Suroviec Spring 2014

  2. I. Definitions of Acids/Bases • Arrhenius • Acid: something that releases H+ in water • Base: something that releases OH- in water • Brønsted-Lowry • Acid: substance that donates a proton • Base: substance that accepts a proton

  3. Monoprotic vs. Polyprotic • Monoprotic • acid – only has 1 proton to donate • base – only can accept 1 proton • Polyprotic • acid – can donate several protons • Base – can accept several protons

  4. Conjugate Acid-Base Pairs • A pair of compounds that differ by the presence of one H+ is called a conjugate acid-base pair • Every reaction between a Brønsted acid and Brønsted base involves H+ transfer and has 2 conjugate acid-base pairs

  5. II. Water Ionization • Water equilibrium Water ionization constant Kw = 1.00 X 10-14 at 25.0oC

  6. II. Water Ionization • pH scale • One way to describe the concentration of H+ in solution or the acidity of the solution

  7. D. Determining [H3O+] and [OH-] pH = 1.00 pH = 10.50

  8. IV. Equilibrium constants A. Acid • Acids and bases are either: • strong electrolytes: completely dissociates • weak electrolytes: ionizes very little in water • Ionization constants measure extent of ionization: • K>1: ionize extensively, strong acid/base • K<1: does not ionize extensively, weak acid/base

  9. B. Bases

  10. C. Compare Acid/Base strength • Look at the pKa value and compare to the acid strength

  11. D. Relationship between Ka, Kb and Kw • As acid strength increases Ka increases • As base strength increases Kb increases • Consider the relation between a conjugate acid-base pair • HB (aq) ⇌ H+ (aq) + B- (aq) KI= Ka of HB • B- (aq) + H2O ⇌ HB (aq) + OH- (aq) KII = Kb of B-

  12. III. Acid/Base reactions A. Strong Acid/Strong Base

  13. B. Strong – Weak

  14. V. Equilibrium Calculations • Determining K from pH 0.015 M HOCN has a pH of 2.67, what is the [H3O+]? What is the Ka of HOCN?

  15. B. Determining the Equilibrium Concentrations and pH from Ka • Weak acid ionization Given a weak acid (HA) concentration of 0.040M with a Ka of 4.0 x 10-9 what are the equilibrium concentrations of HA, A-, H3O+

  16. C. 5% rule • Codeine (Cod) is a powerful and addictive painkiller. It is also a weak base. • Write the reaction of weak base Cod with H2O • If the Ka of Hcod (the weak conjugate acid) is 1.2×10-8, what is the Kb of Cod? • Find the pH of a 2.0×10-3M solution of Cod in water.

  17. VI. Polyprotic Acids • Acids capable of donating more than 1 proton

More Related