1. Unit VII Chapter 15

2. Properties Both acids and bases ionize or dissociate in water Acids: taste sour, conduct electricity, cause certain indicators to change color, and react with metals to form H 2 gas Bases: taste bitter, feel slippery, conduct electricity, and cause certain indicators to change color

3. Recognizing Acids and Bases Most simply, acids tend to have H’s at the beginning of their chemical formulas. Bases tend to have OH’s at the end of their formulas. NOTE: THIS IS NOT THE WHOLE TRUTH...YOU’LL LEARN MORE SOON!

4. Naming Acids and Bases REVIEW: Binary acids Oxyacids Bases (named simply as ionic compounds) pg. 454-458

5. Acid Nomenclature Review Binary  oxyacid An easy way to remember which goes with which… “In the cafeteria, you ATE something ICky”

6. Practice Problems 1.HF 2.HNO 3 3.KOH 4.H 2 SO 4 Answers: 1.Hydrofluoric acid 2.Nitric acid 3.Potassium hydroxide 4.Sulfuric acid

7. Practice Problem 1.Chromic acid 2.Iron (II) hydroxide 3.Acetic Acid 4.Lithium hydroxide Answers: 1.H 2 CrO 4 2.Fe(OH) 2 3.CH 3 COOH 4.LiOH

8. Acid/Base Strength The Strength of an acid/base depends on the degree of ionization/dissociation. Common Aqueous Acids and Bases: Tables 15-3 and 15-4

9. Acid/Base Definitions Arrhenius Acids/Bases Earliest and most specific definition Brønted-Lowry Acids/Bases Middle definition Lewis Acids/Bases Latest and most general definition

10. Arrhenius Acid Definition An acid is a compound that increases hydrogen ions [H+] concentration when dissolved in water. Ex. HCl(g) is named hydrogen chloride. BUT HCl(aq) is named hydrochloric acid.

11. Arrhenius Base Definition A base is a compound that increases hydroxide ion [OH-] concentration when dissolved in water. Ex. NaOH(s) is named sodium hydroxide and is NOT a base. BUT NaOH (aq) is named sodium hydroxide and IS a base.

12. Acidic Solutions An acidic solution is one in which [H 3 O + ] is greater than [OH - ]. Ex. HCl(g) H + (aq) + Cl - (aq) Since the water is already forming some H+ ions (typically in the form of H 3 O+), the HCl is adding more H+ ions. This causes there to be MORE H+ or H 3 O+ ions than OH- ions. H2OH2O

13. Basic Solutions A basic solution is one in which [OH-] is greater than [H 3 O+]. AKA: alkaline solutions Ex. NaOH(s) Na+(aq) + OH-(aq) Since the water is already forming some OH- ions, NaOH is adding more OH- ions. This causes there to be MORE OH- ions than H 3 O+ ions. H2OH2O

14. Arrhenius Acids and Bases Acids are hydrogen-containing compounds that ionize to yield hydrogen ions in aqueous solution... Bases are compounds that ionize to yield hydroxide ions in aqueous solution... BUT...NH 3 is a base! Arrhenius’ theory doesn’t hold up in every case, so...

15. Brønsted-Lowry Acids and Bases An acid is a hydrogen-ion donor, and a base is a hydrogen-ion acceptor. A substance that can either accept or donate depending upon its partner is call amphoteric. Example: NH 3 (aq) + H 2 O(l) NH 4 +(aq) + OH-(aq) Watch the compounds as they react. What happens across the arrow?

16. Practice Problem H 2 SO 4 + H 2 O H 3 O + + HSO 4 - Label the acid, base, conjugate acid, and conjugate base.

17. Lewis Acid/Base Definition Lewis acid - a substance that accepts an electron pair Lewis base - a substance that donates an electron pair

18. Formation of hydronium ion is also an excellent example. Lewis Acids & Bases Electron pair of the new O-H bond originates on the Lewis base.Electron pair of the new O-H bond originates on the Lewis base.

19. Lewis Acid/Base Reaction

20. Conjugate Acids and Bases Every acid on the left side of the reaction equation has a conjugate base on the right side of the equation. There is also the same base/conjugate acid pairing in each equation.

21. Conjugate pairs

22. Practice problems Identify the acid, base, conjugate acid, conjugate base, and conjugate acid-base pairs: acidbase conjugate acidconjugate base HC 2 H 3 O 2 (aq) + H 2 O (l)  C 2 H 3 O 2 – (aq) + H 3 O + (aq) conjugate acid-base pairs acidbase conjugate acidconjugate base OH – (aq) + HCO 3 – (aq)  CO 3 2– (aq) + H 2 O (l) conjugate acid-base pairs

23. Strength of conjugates The stronger the acid/base, the weaker the conjugate base/acid is. See Table 15-6 p.471 Ex: HCl(acid)-Strong acid Cl - (conj. base)-very weak base

24. Neutral Solutions Any aqueous solution in which [OH - ] = [H 3 O + ] is described as a neutral solution. Ex. Pure water Neutralization Reactions are based on equalizing the conc. of acids and bases in solution. (Titration)