1. Acids and Bases

2. These are acids….. HNO 3 HCl H 2 SO 4 HC 2 H 2 OOH H 3 PO 4 What do they all have in common?

3. What all acids have in common… Sour or tart taste (take my word for it) Electrolytes in solution React with metals to produce H 2(g) React with bases to produce water and a salt Change the color of an acid/base indicator Many are in foods and drinks.

4. These are all bases…. NaOH KOH Ca(OH) 2 Mg(OH) 2 What do they all have in common? NH 3 is also a base.

5. What all bases have in common… Taste bitter (take my word for it) Feel slippery on skin (take my word for it) Electrolytes in solution Change the color of an acid/base indicator React with acids to produce water and a salt Almost none are in foods.

6. Arrhenius Acids and Bases Acids ionize in water to produce hydrogen ions (H + ) HCl + H 2 O → H + (aq) + Cl - (aq) Bases ionize in water to produce hydroxide ions (OH - ) NaOH + H 2 O → Na + (aq) + OH - (aq)

7. Brönsted-Lowry Acids and Bases An acid donates a hydrogen ion (H+) HCl + H 2 O → H + (aq) + Cl - (aq) A base accepts a hydrogen ion NH 3(g) + H 2 O (l) → NH 4 + (aq) + OH - (aq)  That’s why NH 3 is listed as a base!

8. Conjugate Acids and Bases HCl + H 2 O → H + (aq) + Cl - (aq) A more accurate version is this: HCl + H 2 O ↔ H 3 O + + Cl - H 3 O + is called hydronium ion We are agreed that reactions are reversible, right?

9. Self-Ionization of Water Sometimes water comes apart: H 2 O ↔ H + (aq) + OH - (aq) If [H + ] = [OH - ] you have a neutral solution In H 2 O, [H + ] = 1.0 x 10 -7 M. So is [OH - ] For any aqueous solution, [H + ] x [OH - ] = 1 x 10 -14 This is called the ion-product constant for water, K w = [H + ] x [OH - ] = 1.0 x 10 -14

10. Self-Ionization of Water In an acidic solution, [H + ] > [OH - ] In an acidic solution, [H + ] > 1.0 x 10 -7 M In a basic solution, [OH - ] > [H + ] In a basic solution, [H + ] < 1.0 x 10 -7 M pH = -log[H + ]

11. pH pH = -log[H + ] In a neutral solution, [H + ] = 1.0 x 10 -7 M What is the pH? If [H + ] = 4.8 x 10 -8 M, what is the pH? If pH = 3.32, what is [H + ]? [H + ] = antilog(-pH)

12. Titration Method of determining the concentration of an acid/base. Let’s say you have an acid of unknown concentration. You add a base, whose concentration is known, until an indicator shows that you are at the equivalence point. Equivalence point is where moles of acid=moles of base.

15. Titration At the equivalence point, M a V a =M b V b During the actual titration, it is HUGELY important that you do not overrun the equivalence point. Example: 40.0mL of a nitric acid solution required 32.6mL of 0.50M NaOH to neutralize it. What is the molarity of the nitric acid?

16. Strong/Weak Acids & Bases

17. What do acids do in water? They IONIZE Some ionize completely (strong), and some hardly ionize at all (weak). Strong acids: HCl, H 2 SO 4, HNO 3, H 3 PO 4, H 2 CO 3, HClO,CH 3 COOH

18. Strong/Weak Acids & Bases K a, the acid dissociation constant, is a ratio that numerically expresses how strong an acid is. Strong acids have a high K a value (1 or higher), and weak acids have a low K a value (far below 1).

19. Salt Hydrolysis Rxns When salts dissolve in water, they dissociate into their component ions. Some of these ions act as weak Bronsted-Lowry acids or bases. There are four possibilities….

20. 1. Salts of Strong Acids and Bases— (NaCl, K 2 SO 4 ) produce neutral solutions 1. Salts of Strong Acids & Weak Bases– (NH 4 Cl) produce slightly acidic solutions

21. 3. Salts of Weak Acids & Strong Bases—(Na 2 CO 3 )produce slightly basic solutions. 4. Salts of Weak Acids and Bases— can produce either acidic, basic, or neutral solutions. Very hard to predict

22. Strong Acids H 2 SO 4 —Sulfuric HNO 3 —Nitric All of the hydrogen halides except fluorine (HCl—Hydrochloric, HBr—Hydrobromic, HI—Hydroiodic)

23. Strong Bases All of the hydroxides of the alkali metals (LiOH, NaOH, KOH, RbOH, CsOH) The hydroxides of the alkaline earth metals except for Be and Mg (Ca(OH) 2, Sr(OH) 2, Ba(OH) 2 )