1. Name ‘Em!
HI (aq)
HCl (aq)
H2SO3
HNO3
HIO4

2. Acid and Bases

3. Acid and Bases

4. Acid and Bases

5. Properties ACIDS BASES electrolytes electrolytes sour taste
bitter taste
turn litmus red
turn litmus blue
react with metals to form H2 gas
slippery feel
vinegar, milk, soda, apples, citrus fruits
ammonia, lye, antacid, baking soda
ChemASAP

6. Properties of acids and bases Acids – Sour taste
– Turns blue litmus paper red
– Reacts with some metals to produce H2
– Dissolves carbonate salts, releasing CO2
Bases
– Bitter taste
– Turns red litmus paper blue
– Slippery to the touch
Copyright © 2007 Pearson Benjamin Cummings. All rights reserved.

7. Common Acids and Bases Strong Acids (strong electrolytes)
Strong Bases (strong electrolytes)
NaOH sodium hydroxide
KOH potassium hydroxide
Ca(OH) calcium hydroxide
HCl hydrochloric acid
HNO3 nitric acid
HClO4 perchloric acid
H2SO4 sulfuric acid
Phosphoric acid, H3PO4, is another acid commonly found in the laboratory. It is on the borderline between a strong and weak acid.
Weak Acids (weak electrolytes)
CH3COOH acetic acid
H2CO3 carbonic
Weak Base (weak electrolyte)
NH ammonia
NH3 + H2O  NH4OH
Kotz, Purcell, Chemistry & Chemical Reactivity 1991, page 145

8. Acid Nomenclature Review
No Oxygen
w/Oxygen
An easy way to remember which goes with which…
“In the cafeteria, you ATE something ICky”

9. Acid Nomenclature Review
HBr (aq)
H2CO3
H2SO3
 hydrobromic acid
 carbonic acid
 sulfurous acid

10. Common Acids Sulfuric Acid H2SO4 Nitric Acid HNO3
Phosphoric Acid H3PO4
Hydrochloric Acid HCl
Acetic Acid CH3COOH
Carbonic Acid H2CO3
Battery acid
Used to make fertilizers
and explosives
Food flavoring
Stomach acid
Vinegar
Carbonated water

11. Common Bases Name Formula Common Name
OH1-
hydroxide
ion
Name Formula Common Name
Sodium hydroxide NaOH lye or caustic soda
Potassium hydroxide KOH lye or caustic potash
Magnesium hydroxide Mg(OH)2 milk of magnesia
Calcium hydroxide Ca(OH) 2 slaked lime
Ammonia water NH3 H2O household ammonia
Bases
– Bases are ionic compounds that contain the hydroxide ion and a metal cation and have the general formula M(OH)n .
– When a base reacts with an acid, it accepts a proton (H+) and is therefore called a proton acceptor.
– Aqueous ammonia solution is also a common base.
– Replacing a hydrogen atom of NH3 with an alkyl group results in an amine (RNH2), which is also a base. Amines have pungent odors. .
NH4OH
NH OH1-
ammonium hydroxide

12. Acid/Base definitions
Definition #1: Arrhenius (traditional)
Acids – produce H+ ions (or hydronium ions H3O+)
Bases – produce OH- ions
(problem: some bases don’t have hydroxide ions!)

13. Arrhenius acid is a substance that produces H+ (H3O+) in water
Arrhenius base is a substance that produces OH- in water

14. Acid/Base Definitions
Definition #2: Brønsted – Lowry
Acids – proton donor
Bases – proton acceptor
A “proton” is really just a hydrogen atom that has lost it’s electron!

15. A Brønsted-Lowry acid is a proton donor
A Brønsted-Lowry base is a proton acceptor
conjugate acid
conjugate base
base
acid

16. ACID-BASE THEORIES
The Brønsted definition means NH3 is a BASE in water — and water is itself an ACID

17. The pH scale is a way of expressing the strength of acids and bases
The pH scale is a way of expressing the strength of acids and bases. Instead of using very small numbers, we just use the NEGATIVE power of 10 on the Molarity of the H+ (or OH-) ion. Under 7 = acid = neutral Over 7 = base

18. Titration
standard solution
unknown solution
Titration
Analytical method in which a standard solution is used to determine the concentration of an unknown solution.
Quantitative analysis — used to determine the amounts or concentrations of substances present in a sample by using a combination of chemical reactions and stoichiometric calculations
Titration
– A method in which a measured volume of a solution of known concentration, called the titrant, is added to a measured volume of a solution containing a compound whose concentration is to be determined (the unknown)
– Reaction must be fast, complete, and specific (only the compound of interest should react with the titrant)
– Equivalence point — point at which exactly enough reactant has been added for the reaction to go to completion
Courtesy Christy Johannesson

19. Buret
stopcock
Erlenmeyer flask

20. Titration Vocabulary Titrant
The substance added to the analyte in a titration (reagent solution)
Analyte
The substance being analyzed
Equivalence point
The point in a titration at which the quantity of titrant is exactly sufficient for stoichiometric reaction with the analyte.

21. Acid-Base Titration Analyte Titrant
If the concentration of the titrant is known, then the concentration of the unknown can be determined.
Titrant
In acid-base titrations, a buret is used to deliver measured volumes of an acid or base solution of known titration (the titrant) to a flask that contains a solution of a base or an acid, respectively, of unknown concentration (the unknown).
If the concentration of the titrant is known, then the concentration of the unknown can be determined.
Plotting the pH changes that occur during an acid-base titration against the amount of acid or base added produces a titration curve; the shape of the curve provides important information about what is occurring in solution during the titration.
Before addition of any strong base, the initial [H3O+] equals the concentration of the strong acid.
Addition of strong base before the equivalence point, the point at which the number of moles of base (or acid) added equals the number of moles of acid (or base) originally present in the solution, decreases the [H3O+] because added base neutralizes some of the H3O+ present.
Addition of strong base at the equivalence point neutralizes all the acid initially present and pH = 7.00; the solution contains water and a salt derived from a strong base and a strong acid.
Addition of a strong base after the equivalence causes an excess of OH– and produces a rapid increase in pH.
A pH titration curve shows a sharp increase in pH in the region near the equivalence point and produces an S-shaped curve; the shape depends only on the concentration of the acid and base, not on their identity.
For the titration of a monoprotic strong acid with a monobasic strong base, the volume of base needed to reach the equivalence point can be calculated from the following relationship:
moles of base = moles of acid
(volume)b (molarity)b = (volume)a (molarity)a
VbMb = VaMa
Analyte

22. Buret Reading

23. Why do chemists use titrations??
Quantitative analysis — used to determine the amounts or concentrations of substances present in a sample by using a combination of chemical reactions and stoichiometric calculations

24. Acidic, basic, or neutral??

25. The “perfect pink” for a titration with phenolphthalein

26. Plotting the pH changes against the amount of acid or base added produces a titration curve
Equivalence point
point at which exactly enough reactant has been added for the reaction to go to completion

27. Indicator - changes color to indicate pH change
pink
Example… phenolphthalein is colorless in acid and pink in basic solution
endpoint 7
colorless
Volume base added

28. Titration Equivalence point (endpoint)
Point at which equal amounts of H+ and OH- have been added.
Determined by…
indicator color change
Most common acids and bases are not intensely colored
– Rely on an indicator
Endpoint — point at which a color change is observed, which is close to the equivalence point in an acid-base titration
dramatic change in pH
Courtesy Christy Johannesson

29. moles H+ = moles OH- Titration M: Molarity V: volume At endpoint...
Courtesy Christy Johannesson

30. Titration calculation:
Calculate the molarity of an acetic acid solution if mL of this solution are needed to neutralize mL of M sodium hydroxide.