1. Acids and Bases

2. Solutions homogeneous mixtures in which one substance is dissolved into another the “solute” dissolves in the “solvent” example: Kool-Aid - water is the solvent, the drink mix is the solute

3. Molarity Molarity of a solution is equal to the number of moles of solute divided by the number of liters of solution M = mol/L New symbol [square brackets] [H + ] = molarity of H + ions The larger the molarity, the more concentrated the solution

4. Concentrated In a concentrated solution, the amount of solute is large compared to the amount of solvent it is dissolved in Ex: juices, detergents

5. Dilute In a dilute solution, there is much more solvent than solute Solutions are “diluted” by adding more solvent 0.5M HCl is more dilute than 2.0M HCl

6. Electrolytes Substances that, when dissolved in water, produce aqueous solutions that will conduct electricity Strong electrolytes release many ions Many ionic compounds Weak electrolytes release few ions

7. Properties of acids React with most metals to produce H 2(g) react with carbonates to produce CO 2 taste sour damage living tissues pH 0 - 7 neutralize bases

8. Common acids Acid formulas – start with H HCl – hydrochloric acid H 2 SO 4 – sulfuric acid HNO 3 – nitric acid H 3 PO 4 – phosphoric acid HC 2 H 3 O 2 – acetic acid Also written CH 3 COOH

9. What is an acid? Many definitions are used Arrhenius acid: a substance that produces H + ions in water Then, H 2 O + H +  H 3 O + H 3 O + = hydronium ion

10. Acid Strength Compare the difference in these two statements: 1)The more H + ions in the water, the more acidic the solution 2)The more H + ions a compound produces, the stronger the acid

11. Acid Strength Strong acids release all of their H + ions [strong acid] = [H + ] Strong acids are strong electrolytes Weak acids hold on to most of their H + ions [weak acid]>>>[H + ] Weak acids are weak electrolytes Weak acids reach equilibrium with “neutralization” products

12. Don’t get confused! A solution of a strong acid can be less acidic that a solution of a weak acid! IF: the strong acid solution is very dilute and the weak acid is concentrated!

13. Properties of bases React with fats and oils to produce soap feel slippery taste bitter damage living tissues pH 7 - 14 neutralize acids

14. What is a base? Commonly called “antacids” Arrhenius base: a substance that produces OH - (hydroxide) ions when added to water

15. Common bases There are three common varieties of bases: 1)Hydroxide compounds (OH - ) ex: NaOH, Ba(OH) 2 2)Carbonates (CO 3 2- ) and bicarbonates (HCO 3 - ) ex: Na 2 CO 3, NaHCO 3, CaCO 3 3)Ammonia (NH 3 ) and amines

16. Hydroxide bases Release hydroxide ions directly into the water NaOH(s)  Na + (aq) +OH - (aq)

17. Carbonates and bicarbonates React with water to produce hydroxide ions CO 3 2- + H 2 O  HCO 3 - + OH - HCO 3 - + H 2 O  H 2 CO 3 +OH -

18. Ammonia and amines React with water to produce hydroxide ions NH 3 + H 2 O  NH 4 + + OH -

19. Chemical indicators Phenolphthalein acids = colorless bases = pink Litmus acids = red bases = blue

20. Autoionization of water u Water molecules can react with each other u H 2 O + H 2 0  H 3 O + + OH - u At 25ºC, [H 3 O + ] = [OH - ] u [H 2 O] is a constant u K w = [H 3 O + ] [OH - ] = 1x10 -14

21. u Let’s use [H+] instead of [H 3 O + ] u Pure water is neutral [H + ] = [OH - ] If [H + ] > [OH - ], the solution is acidic If [H + ] < [OH - ], the solution is basic

22. pH scale Used to indicate the acidity or “basicity” of a solution tells how strongly acidic a solution is - NOT how strong an acid is! Think pH as “parts H + ” the lower the pH, the more H + ’s, the more acidic the solution

23. pH calculation pH = -log [H + ] [H + ] = 10 -pH

24. pH scale u The pH is the measurement of how many H + ’s are in the water – NOT a measure of if the H + ’s came from a “strong” or “weak” acid!!!

25. pH scale 0 - 2 strongly acidic 2 - 4 moderately acidic 4 - 7 weakly acidic 14 - 12 strongly basic 12 - 10 moderately basic 10 - 7 weakly basic

26. pOH calculation pOH = -log [OH - ] [OH - ] = 10 -pOH

27. pH & pOH relationship In pure water at 25°C: [H+] = 1x10 -7 M [OH-] = 1x10 -7 M Therefore, [H + ] x [OH - ] = 1x10 -14 And pH + pOH = 14

28. Arrhenius Neutralization u Works for the reaction of a strong acid with a strong base u Remember – acid (or base strength) has to do with how much of the acid (or base) ionizes in water, not directly how many H+ or OH- are produced u 100% ionization = “strong”

29. Arrhenius Neutralization Hydroxide base – general form Acid + Base  Salt + H 2 O what’s actually happening? H + + OH -  H 2 O anion from acid + cation from base = salt

30. Arrhenius Neutralization Examples with a hydroxide base NaOH + HCl  NaCl + H 2 O 3H 2 SO 4 + 2Al(OH) 3  Al 2 (SO 4 ) 3 + 6H 2 O

31. Arrhenius Neutralization carbonate base – general form Acid + Base  Salt + H 2 O + CO 2 what’s actually happening? 2H + + CO 3 2-  H 2 CO 3 H 2 CO 3  H 2 O + CO 2 anion from acid + cation from base = salt

32. Arrhenius Neutralization Examples with a carbonate base CaCO 3 + 2 HCl  CaCl 2 + H 2 O + CO 2 H 2 SO 4 + NaHCO 3  Na 2 SO 4 + H 2 O + CO 2