1. Acids-Bases Arrhenius: Acid…. A substance that increases the hydrogen ion, H +, concentration when dissolved in H 2 O. Eg. HCl, H 2 SO 4, HC 2 H 3 O 2 (CH 3 COOH), etc. Base…. A substance that increases hydroxide ion, OH -, concentration. Eg. NaOH, NH 4 OH, etc. Bronsted-Lowry (1923) (not worried about increasing/decreasing H + or OH - concentrations) Acid … a “proton donor”, p + = H +, any formula HA. Eg. HCl, H 2 SO 4, HC 2 H 3 O 2 (CH 3 COOH), etc. Base …. A “proton acceptor” Eg. OH -, NH 3 ; Cl - Note: HOH can do both! Really no different from Arrhenius. This is different from Arrhenius!

2. Acid solutions: HCl (g) + H 2 O (l) H 3 O + (aq) + Cl - (aq) H 3 O + (aq) = H + (aq) H:Cl:.. + :O::O: H H H H :O::O: H + + :Cl:.. - Hydrogen ion, H +, or hydronium ion, H 3 O + has formed HCl (g) + H 2 O (l) H + (aq) + Cl - (aq) Bronsted and Lowry would say the HCl donated a p + (H + ion), and the water accepted a p + (H + ion). Either way the HCl is an acid. The water is a base ….it was a proton acceptor! Coordinate covalent bond Arrhenius would say the concentration of H+ has increased.

3. Strength of an acid can be determined by conductivity. 12 M HCl Good or poor electrolyte? Large or small # of ions? goodLarge HCl (g) + H 2 O (l) H 3 O + (aq) + Cl - (aq) Initially: 100 0 0 @equil: 0 100 100 K a = [H 3 O + ] [Cl - ] [HCl] = Large value Strong Acid Acids with K a values greater then “1” are considered strong acids. They 100% ionize. Note: 100% pure HCl is a poor conductor. Why? No ions!

5. Strength of an acid can be determined by conductivity. Good or poor electrolyte?Large or small # of ions? Pure HC 2 H 3 O 2 no conduction none Diluted HC 2 H 3 O 2 poor small HC 2 H 3 O 2 (g) + H 2 O (l) H 3 O + (aq) + C 2 H 3 O 2 - (aq) Initially: 100 0 0 @equil: 97 3 3 < 5% ionization….. Very weak acid Weak acid K a = [H 3 O + ][C 2 H 3 O 2 - ] [HC 2 H 3 O 2 ] = a Very small #= 1.76 X 10 -5

6. Properties of Acids: 1. Conduct electricity if they ionize. 2. React with metals to form H 2 3. Neutralize bases. 4. Turn litmus red 5. Taste sour

7. More Bronsted-Lowry Acid/Base info: General acid/base reaction: HA + B = A - + HB + acid 1 base 2 base 1 acid 2 conjugate Acid/base pair HCl (aq) + NH 3 (aq) = NH 4 + (aq) + Cl - (aq) acid 1 base 2 acid 2 base 1 Which direction is favored? Which is a stronger acid? HCl…. K a is larger At equilibrium there is more ________________ product

8. Titration problems What is the volume of a 0.325 M NaOH solution needed to just neutralize 65.2 ml of 1.37 M HNO 3 ? Balanced equation: 1 NaOH + 1 HNO 3 = 1 HOH + 1NaNO 3 65.2ml xxxxx = 274.8 = 275ml NaOH Or using: M a V a # H ’ s = M b V b # OH ’ s (1.37M)(65.2ml)(1) = (0.325M)(V b )(1) V b = 275ml * Since they equal the same # of moles!

9. Basic Solutions: Strong Arrhenius bases: 1.Group IA hydroxides. Eg. NaOH, KOH 2.Lower Group IIA hydroxides. Eg. Sr(OH) 2, Ba(OH) 2 100% “Dissociate”: NaOH (S) Na + (aq) + OH - (aq) 1.0 M Ba(OH) 2 = 1.0mol Ba +2 + 2.0mol OH - The K b for these bases would be very large; > than 1. They would also be good conductors of electricity. 1.Acid anions of weak acids: eg. C 2 H 3 O 2 -, from HC 2 H 3 O 2 or OH -, from HOH Strong Bronsted-Lowry bases:

10. More Bronsted-Lowry Acid/Base info : Bases react with water to produce OH - General equation: B (g) + H 2 O (l) = BH + (aq) + OH - (aq) NH 3(g) + H 2 O (l)  NH 4 + (aq) + OH - ( aq ) Base 1 acid 2 acid 1 base 2 K b =[NH 4 + ][OH - ] [NH 3 ] = 1.79 x 10 -5 Which direction is favored in the reaction?

11. Lewis Acid/Base Lewis acid: electron pair acceptor Lewis base: electron pair donor H+H+ + :N:.. H H H Lewis acid Lewis base.. H H H H ::N + “adduct” … the product of a L.acid/base rxn

12. Acid-Base Equilibria Review: In pure water & all aqueous solutions: H 2 O + H 2 O = H 3 O + + OH - K w = [ H 3 O + ][OH - ] = 1 x 10 -14 [H 3 O + ] = [OH - ] = 1x10 - 7 or = [H 3 O + ] > [OH - ] = Acidic solution [H 3 O + ] < [OH - ] = Basic solution [H 3 O + ] = [OH - ] = Neutral solution

13. Solutions of Strong Acids/ Bases: 0.10 M HNO 3 actually consists of 0.10 M H 3 O + or [H + ] = 0.10 M 0.10 M NaOH…. Adds 0.10 OH - to the water solution Ionization & dissociation are 100% for strong acids & bases HNO 3 + H 2 O =  H 3 O + + NO 3 - NaOH + H 2 O =  Na + (aq) + OH - (aq) In 0.10M Ba(OH - ) 2 [OH - ] = GONE In 0.20 M H 2 SO 4 [H + ] = 0.20M 0.40 M

14. pH A simple scale for ranking the H 3 O + concentrations of dilute acid/base solutions. (Sorenson). pH = - Log [ H 3 O + ] The logarithm of a number is that number expressed as an exponent of the base 10. For example, the logarithm of 1 is 0, 1 x 10 0. If [H 3 O + ] = 0.001 = pH = -log 0.001 = If this is 1 This is the pH 1x10 -3 3

15. pH Scale neutral pH7 [H3O+][H3O+] 1x10 -7 [OH - ]1x10 -7 pOH 7 Acidity increases 10 -6 6 10 -8 8 0 1 2 3 4 5 10 0 10 -1 10 - 2 10 - 3 10 -4 10 - 5 10 -12 12 [H 3 O + ][OH - ]= 1x10 -14 pH = - log[H 3 O] pH + pOH = 14 Formulas to remember 1M HA 8 10 -8 10 -6 6 Basicity increases 9 10 11 12 13 14 10 -9 10 -10 10 -11 10 -12 10 -13 10 -14 10 -3 3 1M BOH 10 0

16. [H 3 O + ] = 3.25 x 10 - 4 Given a 3.25 x 10 -4 M HNO 3, solve for: a.[H 3 O + ] a.pH = a.[OH - ] = HNO 3 is a strong acid. Thus, 3.25 x 10 -4 M HNO 3 = -log [3.25 x 10 -4 ] prediction = -(-3.488) =3.49 1 x 10 -14 3.25 x 10 -4 = 3.08 x 10 -11 d. pOH =-log [OH - ]= -log [3.08 x 10 -11 ]= 10.5 Or pOH = 14.00 –3.49 = 10.51 More About the pH Scale