1 / 19

Acid-Base Theories

Acid-Base Theories. And Much More. Arrhenius Theory. An Acid is a substance that produces H+ ions in solution. A base is a substance that produces OH- ions in solution. Neutralization occurs when H+ ions combine with OH- ions to form water. Acid or Base (Arrhenius Style). H 2 SO 4

tanisha-orr
Télécharger la présentation

Acid-Base Theories

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. Acid-Base Theories And Much More

  2. Arrhenius Theory An Acid is a substance that produces H+ ions in solution. A base is a substance that produces OH- ions in solution. Neutralization occurs when H+ ions combine with OH- ions to form water.

  3. Acid or Base (Arrhenius Style) • H2SO4 • Ca(OH)2 • Pb(NO3)2 • NaHCO3 • NaOH • HBr

  4. Limitations of Arrhenius Theory • Acids (like HCl) are able to be neutralized by NaOH and NH3. • Not all bases have OH- ions, NH3 in H2O does, but, if NH3 reacts as a gas with HCl gas, NH4Cl is still formed, but is not a solution, so this theory won’t always work.

  5. Bronsted-Lowry Theory • An acid is a proton donor. • A base is a proton acceptor. H3O+ is a hydronium ion (aka. THE PROTON) H2O is the base. HCl is the acid

  6. Writing Conjugates • See Board notes

  7. Conjugate Acid-Base Pairs A conjugate acid is the substance that has accepted the proton (gained an H+) A conjugate base is the substance that has lost the proton. Each acid has a conjugate base and each base has a conjugate acid.

  8. Lewis Theory In the Lewis theory of acid-base reactions, bases donate pairs of electrons and acids accept pairs of electrons. A Lewis acid is therefore any substance, such as the H+ ion, that can accept a pair of nonbonding electrons. In other words, a Lewis acid is an electron-pair acceptor. A Lewis base is any substance, such as the OH- ion, that can donate a pair of nonbonding electrons. A Lewis base is therefore an electron-pair donor.

  9. Ionization Constants Acid ionization constant (Ka) Base ionization constant (Kb) Magnitude dictates the strength of the base Strong bases have large Kb values – and dissociate completely (100%)  Weak bases have small Kb values - and do not dissociate completely (5% or so)  • Magnitude dictates the strength of the acid • Strong acids have large Ka values – this means that they dissociate completely (100%)  • Weak acids have small Ka values – and do not dissociate completely (usually 5% or so) 

  10. Relative Strengths of Acids and Bases

  11. Self-ionization of Water

  12. Ion Product of Water (Kw) Kw = 1.0 x 10-14=[H+][OH-] – changes with temperature Kw = Ka x Kb • Uses: Can find concentration of OH- or H+, the Kb of the conjugate base (and vice versa), or used with pH or pOH calculations when necessary

  13. pH and pOH pH = -log10[H+] or pH = -log10[H3O+] (same thing) [H+] = 10-pH pOH = -log10[OH-] [OH-] = 10-pOH

  14. pH Scales

  15. Strong Acids & Bases • Strong acids – hydrogen halides, oxyacids of halogens, sulfuric acid & nitric acid • Strong bases – NaOH, KOH, Cs(OH)2, Ca(OH)2 • Both of these ionize completely in H2O.

  16. Weak Acids & Bases • Weak acids and bases do not ionize completely in water • A weak acid/base will be shown with a double arrow reaction, and also have small Ka and Kb values

  17. Ionization Constants of Weak Acids & Bases

  18. Equilibrium Problems Using Acids Type 1: Solving for Ka You must have the following: - the equation for the reaction - the equilibrium expression - the concentrations at equilibrium (ICE chart) - The concentrations at equilibrium are usually found with pH or a % ionization.

  19. Equilibrium Problems Using Acids Type 2. Solving for EQ amounts You must have the following: - the reaction - the equilibrium expression and Ka value - the initial concentration of the acid (in mol/L) - With this type, it may ask for the pH at equilibrium

More Related