1 / 18

Understanding Acid-Base Strengths and Properties

Learn about the strength of acids and bases, including strong acids that dissociate completely and weak acids that only partially dissociate. Discover the key concepts of acid dissociation constant (Ka) and base dissociation constant (Kb) to measure acid and base strength. Practice solving problems to calculate Ka for weak acids. Understand how salts formed from different acid-base combinations exhibit varying properties. Master the rules for predicting acid-base properties of salts based on the types of acids and bases involved.

tori
Télécharger la présentation

Understanding Acid-Base Strengths and Properties

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. Determining Strengths of Acids and Bases (This section is in Chp 18 pages 605 – 612)

  2. - + Strength • Strong Acids – Dissociate almost completely in water to produce H3O+ ions • Strong Bases – Strongly attract hydrogen ions in water, thus leaving OH- STRONG ACIDS "The Big Six” STRONG BASES HBr HI HClO4 HCl HNO3 H2SO4 Ca(OH)2 CaO NaOH KOH

  3. - + Strength • Weak Acids – Dissociate slightly in water to produce H3O+ ions. Do not readily dissociate. • Weak Bases – react only partially with water to form OH- ions. WEAK BASES WEAK ACIDS HF HC2H3O2 H3PO4 CO32- PO43- NH3 H2NNH2 H2CO3 HCN

  4. HC2H3O2 + H2O HC2H3O2 + H2O H3O++ C2H3O2– H3O++ C2H3O2– SINGLE ARROW Strong Acid: HCl + H2O  H3O+ + Cl– DOUBLE ARROW Weak Acid:

  5. SINGLE ARROW Strong Base: CaO Ca2+ + O2– O2–+ H2O 2OH– DOUBLE ARROW Weak Base: CO32-+ H2O HCO3- + OH–

  6. Strong & Weak

  7. Acid Dissociation Constant Ka is a measure of the strength of an acid. HA(aq)+ H2O (l) H3O+ (aq)+ A– (aq) The greater the Ka, the stronger the acid! Ka = [H3O+][A-] [HA]

  8. If the acid is diprotic or triprotic, the loss of each hydrogen is a separate ionization. Each ionization results in a different Ka value.

  9. Base Dissociation Constant Kb is a measure of the strength of a base. B(aq)+ H2O(l) HB(aq)+ OH– (aq) The greater the Kb, the stronger the base! Kb = [HB][OH-] [B]

  10. Practice Problem #1 Acetic acid is a weak monoprotic acid. If the initial concentration of acetic acid is 0.200 M and the equilibrium concentration of H3O+ is 0.0019 M, calculate Ka for acetic acid. HA(aq)+ H2O(l) H3O+ (aq)+ A– (aq) [H3O+][A-] Ka = [HA]

  11. Practice Problem #1 HA(aq)+ H2O(l) H3O+ (aq)+ A– (aq) [H3O+][A-] Ka = [H3O+] = [A-] [HA] Use Stoichiometry! The reaction produces an A- ion for every H3O+ ion.

  12. Practice Problem #1 HA(aq)+ H2O(l) H3O+ (aq)+ A– (aq) The equilibrium concentration of HA equals its initial concentration minus the amount that ionizes. [H3O+][A-] Ka = [HA] [HA] = 0.200M – 0.0019M [HA] = 0.1981M

  13. Practice Problem #1 HA(aq)+ H2O(l) H3O+ (aq)+ A– (aq) [H3O+][A-] (0.0019M)(0.0019M) Ka = = [HA] (0.1981M) [H3O+] = [A-] = 0.0019M = 1.8 x 10-5 [HA] = 0.1981M

  14. Acid-Base Properties of Salts Salts dissociate in water to form H3O+ or OH- Knowing what type of acid and base formed the salt helps predict salt solution acid-base properties.

  15. Acid-Base Properties of Salts RULES: Strong Acid + Strong Base Neutral Salt Strong Acid + Weak Base Acidic Salt Weak Acid + Strong Base Basic Salt Weak Acid + Weak Base Cannot predict very easily

  16. Neutral Salt HCl + NaOH NaCl STRONG ACID & BASE

  17. Acidic Salt NH3 + HCl NH4Cl WEAK BASE STRONG ACID

  18. Basic Salt NaOH + H2CO3 Na2CO3 STRONG BASE WEAK ACID

More Related