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 -

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)

3. Strength of an acid can be determined by conductivity. 12 M HCl Good or poor electrolyte? Large or small # of ions? HCl (g) + H 2 O (l) H 3 O + (aq) + Cl - (aq)

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 Diluted HC 2 H 3 O 2

6. Properties of Acids:

7. More Bronsted-Lowry Acid/Base info: General acid/base reaction: HA + B = A - + HB +

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

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

10. More Bronsted-Lowry Acid/Base info: Bases react with water to produce OH -

11. Hydrolysis Salt + H 2 O  Acidic solution Neutral solution Basic solution

12. NaClO + H 2 O : NaClO is a salt of a base NaOH and an acid HClO Hydrolysis (continue)

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

14. Acid-Base Equilibria Review: In pure water & all aqueous solutions: H 2 O + H 2 O = H 3 O + + OH -

15. 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

16. Solutions of Weak acids/bases 0.10 M HC 2 H 3 O 2 : a weak acid - when it reacts with water it does not ionize 100%. What is the [H 3 O + ] for this solution? K a = 1.8 x 10 -5

17. K a = [H 3 O + ][C 2 H 3 O 2 - ] [HC 2 H 3 O 2 ] =1.8 x 10 -5 [H 3 O + ] = [C 2 H 3 O 2 - ] = [HC 2 H 3 O 2 ] = Weak acids (continue)

18. 2 = 1.8 x 10 -5 So…. Weak acids (continue)

19. Weak bases…. B + H 2 O = BH + + OH - NH 3 + H 2 O =

20. If the [OH - ] = 2.5 x 10 -3, what is the [H 3 O + ]? Weak bases (continue)

21. pH A simple scale for ranking the H 3 O + concentrations of dilute acid/base solutions. (Sorenson). 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.

22. pH Scale [H 3 O + ][OH - ]= 1x10 -14 pH = - log[H 3 O] pH + pOH = 14 Formulas to remember

23. Given a 3.25 x 10 -4 M HNO 3, solve for: a.[H 3 O + ] b.pH = c.[OH - ] = More About the pH Scale

24. What is the pH of a 0.10 M HC 2 H 3 O 2 solution? K a = [H 3 O + ][C 2 H 3 O 2 - ] [HC 2 H 3 O 2 ] = 1.8 x 10 -5 Sample Problem