1. Acids and Bases: an Introduction

2. Acids Sour Taste Electrolytes
Identified by the presence of H+ ions (Arrhenius).
Proton (H+) donor (Bronsted-Lowry).
Common Acids: vinegar, citric acid, sulfuric acid, hydrochloric acid.
There are many different ways acids can be defined. For our purposes, acids have an H and produce H ions and bases have an OH and produce hydroxide ions.
Acids—donates hydrogen ions
Vinegar (acetic acid), hydrochloric acid (HCl)—present in our stomach/stomach acid that helps digest food, citric acid present in fruits such as organges and lemons, sulfuric acid (H2SO4) present in car batteries
Write down compounds: HCl, H2SO4, HNO3
NEVER add water to acid, ALWAYS ACID TO WATER (A—W), wear eye protection when working with them.

3. ACIDS An acid  H+ in water HNO3, nitric acid HNO3  H+ + NO3-
Strong acids are strong electrolytes and completely dissociate in water.
HNO3, nitric acid
HNO3

4. ACIDS An acid  H+ in water HCl hydrochloric HBr hydrobromic
The following are examples of strong acids.
HCl hydrochloric
HBr hydrobromic
HI hydroiodic
HNO3 nitric
H2SO4 sulfuric
HNO3

5. HCl (aq)  H3O+ (aq) + Cl-(aq)
The Hydronium Ion
Free H+ is highly reactive and does not actually exist in nature. It reacts with water to form the hydronium ion, H3O+.
HCl (aq)  H3O+ (aq) + Cl-(aq)
HCl H 2 O 3 + Cl -
hydronium
ion

6. Weak Acids
WEAK ACIDS are weak electrolytes and do not completely dissociate in water.
CH3CO2H acetic acid
H2CO3 carbonic acid
H3PO4 phosphoric acid
Dissociation of a Weak Electrolyte

7. Bases Bitter taste Slippery Like acids, they are electrolytes
Identified by the presence of OH- ions (Arrhenius).
Proton (H+) acceptor (Bronsted-Lowry).
Proton acceptor—receives hydrogen ions
Compounds: NaOH (lye), Mg(OH)2—anyone know what this is? Milk of Magnesia, baking soda, ammonia (NH3)
Bases can be used as antacids—acid reflux.

8. BASES Base  OH- in water NaOH(aq)  Na+(aq) + OH-(aq) 04m08an1
NaOH is a strong base
Strong bases are strong electrolytes and soluble in water

9. Strength of Acids and Bases
Based on the concentration of H+ or OH- ions in a solution.
Strong Acids/Bases: completely dissociate into ions in a solution.
Weak Acids/Bases: do NOT completely dissociate into ions in a solution.
Think about strong vs. weak coffee or tea. More stuff in concentrated solution—therefore stronger.
Strong: completely break up into ions, write on board: HCl --- H+ + Cl- , we don’t have to worry about factoring water in.
Weak: acids/bases not completely broken into ions, must write reaction in reverse as some ions will reform. Write acetic acid (weak acid) on board– CH3CO2H + H2O --- H3O+ + CH3CO2- (we can write H as hydronium ion H3O)
**Give List**

10. Strong Acid Example: HCl

11. Weak Acid Example: CH3CO2H

12. “BIG 6”---Strong Acids (Know them!!)
HClO4 HI
HCl
HNO3
HBr
H2SO4

13. Strong Bases (Know them!!)
Group I metal hydroxides (NaOH, KOH, etc.)
Soluble/Slightly soluble Group II metal hydroxides ( Ca(OH)2, Sr(OH)2, Ba(OH)2 )

14. Conjugate Acids/Bases
Acids and bases are related to each other through the addition/loss of hydrogen ions
Conjugate acid-base pairs
Acids produce conjugate bases
Bases produce conjugate acids

15. Conjugate Examples
HA + H2O  H3O+ + A-
HNO3 + NH3  NH NO3-

16. Conjugate Acid/Base Strength
Stronger the acid, the weaker the conjugate base
Stronger the base, the weaker the conjugate acid
Weak acids/bases have strong conjugate bases/acids

17. Acid Nomenclature
Binary acids– containing only 2 elements (one is hydrogen)
1) Prefix “hydro—” with binary acid
2) root name for second element
3) End the name with “IC acid”
Oxyacids– acids containing hydrogen, oxygen, and a nonmetal
1) use the given polyatomic ion name from anion
2) add “IC acid”

18. Naming Acids Binary acids contain only two different elements. Formula
Name HF
hydroflouoric
HCl
hydrochloric
HBr
hydrobromic HI
hydriodic

19. Naming Acids Oxyacids contain a polyatomic ion containing oxygen.
Formula
Name
Polyatomic Anion
CH3COOH
Acetic Acid
CH3COO-
H2CO3
Carbonic acid
CO32-
HNO3
Nitric Acid
NO3-
H2SO4
Sulfuric Acid
SO42-
H3PO4
Phosphoric Acid
PO43-

20. Example 1: HBr
Write name
Hydrobromic acid

21. Now you try, HCl
Write name.
Hydrochloric acid

22. Example 2: Hydrofluoric acid
Write chemical formula HF

23. Now you try, hydriodic acid.HI

24. Example 3: H2SO4 Write the name. Sulfuric acid
-name these acids based on the anion, look at your reference packet when you notice that it is a polyatomic ion.
Sulfate—drop –ate, and add –ic acid ending.

25. Example 4: HClO2 Write the name. -ous ending due to one less oxygen
Chlorous acid.

26. Try:
HClO3
HClO
HClO4
Chloric acid, 2) hypochlorous acid, 3) perchloric acid

27. Base Nomenclature Name of cation, name of anion/hydroxide Ex. NaOH
Sodium hydroxide.

28. Brainstorm…
Briefly brainstorm how we measure the amount of hydrogen ions in a solution? How can we quickly measure the acidity or basicity of a solution?

29. pH
How do we measure the amount of “stuff” in a solution? **concentration**
How do we determine a solution’s concentration? **molarity
Same way with acids and bases except we look at the hydrogen and hydroxide ions to determine how concentrated (ie acidic or basic) a solution is.
How can we measure the acidity or basicity of a solution? How would this measurement relate to the hydrogen and hydroxide ion concentrations in solution?

30. Let’s take a look at water
2H2O  H3O+ + OH-
[H3O+][OH-]= 1x10-14M2
[H3O+]= 1x10-7M
[OH-]= 1x10-7M
Kw= 1x10-14M2
When water is neutral (neither acidic or basic), hydrogen and hydroxide ions dissociate and each have a concentration of 1x10-7 mol/L or M.
This value is obtained at 25 degrees Celcius and equilibrium.
If we combine these concentrations together, the product = 1x10-14M = Kw (water dissociation equilibrium constant)
Ions dissociate in water is small compared to when acid or base is added SO we will be looking at concentrations of the acid or base added. We are only going to be dealing with strong acids and bases

31. Example 1
An acid is added to water and gives a hydroxide ion concentration [OH-] of 1.0x10-12M. What is the hydrogen ion concentration [H+] ?
What happens to the hydrogen ion concentration when we add acid to water? What about hydroxide ions with base?
Example 1: [OH-] = 1.0x10-12M
*Write equation, 1.0x10-14M2 = [H+][OH-], plug in what we know and solve.
1.0x10-14M = [H+] (1.0x10-12M), [H+] = 0.01M or 1x10-2M **So this value tells us the concentration of a solution, how acidic it is? Is this value easy to understand? NO, so the pH scale was developed to easily determine how acidic or basic a solution is.
how many of you have used a pH meter or pH indicators for a pool, hot tub, etc.? Why do you need to know the pH, what do you do? We have certain pH levels that must be maintained in our body for us to function normally (blood pH, stomach acid pH, etc.). *may mention buffers as a way of ensuring pH levels remain stable*

32. What is pH? Pouvoir hydrogene: “hydrogen power”
pH = measure of [H3O+] Acidity
[H3O+] expressed in powers of 10
Ex to 10-1

33. pH Scale Range from 0-14. NEUTRAL, pH=7. (pure water)
BASE, pH > 7. (ocean water, milk of magnesia, baking soda)
ACID, pH < 7. (stomach acid/HCl, vinegar, soft drinks)
Logarithmic scale= base 10 system, relationship between a solution’s acidity/basicity and the concentration of H+ ions in solution
Ex. [H+] = 1x10-7 is a pH of 7 (take the negative log), neutral.
[H+] = 1x10-10 is a pH of 10, basic, more or less hydrogen ions in solution? LESS * draw out number
[H+] = 1x10-2 is a pH of 2, acidic, more or less hydrogen ions in solution? MORE *draw out number
Blood pH is , mostly neutral.
Hydrogen ion concentration is inversely proportional to the scale (pH goes down/increase H ions, pH goes up/decrease H ions)—try with OH ions too. *have students write it down.

34. pH Scale
Draw pH scale. Look at common things on scale.

35. How do we measure the pH of a solution?
Acid-base indicators (ex. litmus paper)
pH meter
Ask students if they have measured pH in a pool, etc. What did they use?
Once we get the pH of a solution, how can we find the concentration of H ions in a solution? Use the log relationship between pH and H ions
Types of indicators: methyl red, phenolphtalein, methyl orange (indicators have a certain pH range for a color change)