1. Acids & Bases
Honors Chemistry
Mrs. Partridge

2. Definition of pH
pH comes from the French word “pouvior hydrogene” which means hydrogen POWER!
So therefore, pH is a measure of the hydrogen concentration in solution

3. Properties of Acids Acids taste sour Acids effect indicators
Blue litmus turns red
Methyl orange turns red
Acids have a pH lower than 7
Acids are proton (hydrogen ion, H+) donors
Acids react with certain active metals, produce H2 (g) and an ionic compound
Aqueous solutions are electrolytes – can conduct electricity
Acids react with carbonates
Acids neutralize bases

4. Names & Formulas
Acids – compounds that produce hydrogen ions when dissolved in water
Chemical formula will be HX where X is either a monatomic or polyatomic ion
Anion Ending
Example
Acid Name
-ide
Cl-, chloride
Hydro – (stem)- ic acid
Hydro-chloric acid
-ate
NO3-, nitrate
(stem) –ic acid
Nitric acid
-ite
SO32-, sulfite
(stem) – ous acid
Sulfurous acid

5. Acids you must know: Strong Acids Weak Acids Sulfuric acid, H2SO4
Phosphoric acid, H3PO4
Hydrochloric acid, HCl
Acetic acid, HC2H3O2
Nitric acid, HNO3

6. Sulfuric Acid Used in the production of paper
Highest volume production of any chemical in the U.S.
Used in the production of paper
Used in production of fertilizers
Used in petroleum refining

7. Nitric Acid Used in the production of fertilizers
Used in the production of explosives
Nitric acid is a volatile acid – its reactive components evaporate easily
Stains proteins (including skin!)

8. Hydrochloric Acid Used in the pickling of steel
Used to purify magnesium from sea water
Part of gastric juice, it aids in the digestion of protein
Sold commercially as “Muriatic acid”

9. Phosphoric Acid A flavoring agent in sodas
Used in the manufacture of detergents
Used in the manufacture of fertilizers
Not a common laboratory reagent

10. Acetic Acid Used in the manufacture of plastics
Used in making pharmaceuticals
Acetic acid is the acid present in vinegar

11. Acids are Proton Donors
Monoprotic acids
Diprotic acids
Triprotic acids
H3PO4
HCl
H2SO4
HC2H3O2
H2CO3
HNO3
Monoprotic – containing 1 ionizable H
Diprotic – containing 2 ionizable H
Triprotic – containing 3 ionizable H
Polyprotic – acids that include both diprotic & triprotic

12. Ionization of HCl and formation of hydronium ion, H3O+
H2O + HCl 
H3O+ + Cl-
Proton
acceptor
Proton
donor

13. Strong Acids vs. Weak Acids
Strong acids are assumed to be 100% ionized in solution (good proton donors).
HCl
H2SO4
HNO3
Weak acids are usually less than 5% ionized in solution (poor proton donors).
H3PO4
HC2H3O2
Organic acids

14. Strong Acid Dissociation

15. Weak Acid Dissociation

16. Organic Acids
Organic acids all contain the “carboxyl” group, sometimes several of them.
The carboxyl group is a poor proton donor, so ALL organic acids are weak acids.

17. Examples of Organic Acids
Citric acid in citrus fruit
Malic acid in sour apples
Deoxyribonucleic acid, DNA
Amino acids, the building blocks of protein
Lactic acid in sour milk and sore muscles
Butyric acid in rancid butter

18. Acids Effect Indicators
Blue litmus paper turns red in contact with an acid.

19. Acids Have a pH less than 7

20. Acids React with Active Metals
Acids react with active metals to form salts and hydrogen gas.
Mg + 2HCl  MgCl2 + H2(g)

21. Acids React with Carbonates
2HC2H3O2 + Na2CO3
2 NaC2H3O2 + H2O + CO2

22. Products of Neutralization
HCl + NaOH 
NaCl + H2O
H2SO4 + Ca(OH)2 
CaSO H2O
HNO3 + KOH 
KNO3 + H2O
The products of neutralization are always a ______ and _______.
salt
water

23. Acids Neutralize Bases
HCl + NaOH  NaCl + H2O
Neutralization reactions ALWAYS produce a salt and water.

24. Effects of Acid Rain on Marble (calcium carbonate)
George Washington:
BEFORE
George Washington:
AFTER

25. Properties of Bases Bases effect indicators Red litmus turns blue
Bases taste bitter
Bases effect indicators
Red litmus turns blue
Phenolphthalein turns purple
Bases have a pH greater than 7
Bases are proton (hydrogen ion, H+) acceptors
Solutions of bases feel slippery
Bases neutralize acids

26. Examples of Bases Sodium hydroxide (lye), NaOH
Potassium hydroxide, KOH
Magnesium hydroxide, Mg(OH)2
Calcium hydroxide (lime), Ca(OH)2

27. Bases Effect Indicators
Red litmus paper turns blue in contact with a base.
Phenolphthalein turns purple in a base.

28. Bases have a pH greater than 7

29. Bases Neutralize Acids
Milk of Magnesia contains magnesium hydroxide, Mg(OH)2, which neutralizes stomach acid, HCl.
2 HCl + Mg(OH)2
MgCl2 + 2 H2O

30. Inequalities
An acid solution is one in which [H+] is GREATER THAN the [OH-]
A basic solution is one in which the [OH-] is greater than [H+]
Basic solutions are also known as alkaline solutions

31. Neutral Solutions The [OH-] is equal to the [H+] pH = 7
Neutralization:
An acid and base react in an aqueous solutions to produce a salt and water
Double Replacement Reaction
HCl + NaOH  NaCl + HOH (H2O)
One mole of H+ reacts with one mole of OH-. This stoichiometric ratio means that one mole of acid will neutralize one mole of base

33. Amphoteric Substances
Substances that can act as either an acid or a base
Example: water

34. Acidic and Basic Anhydrides
The term anhydrous means without water
An acidic anhydride is an acid which has had the water removed
Example: HNO3  N2O5
A basic anhydride is a base which has had the water removed
Example: LiOH  Li2O

35. Concentrated vs Dilute
Molarity is often used to express the concentration of an acid or base
Molarity (M) = moles (mol) / volume in liters (v)
Note: strong acids and weaks acids have the capability of being concentrated or dilute!

36. Indicators
A weak acid or base that undergoes dissociation in a known pH range
Indicators respond (change colors) to pH changes over a specific range

37. Net Ionic Equations for Acids and Bases
When writing the net ionic equation for a neutralization reaction, strong acids and bases are broken up into their ions, while weak acids and bases are kept as a complete molecule.

38. Net Ionic Equations for Acids and Bases
There are 7 rules to decide whether a substance should be written as an ion or a complete molecule:
Binary acids – HCl, HBr, and HI are strong. All other binary acids and HCN are weak.
Ternary acids – if the number of oxygen atoms exceeds the number of hydrogen atoms by 2 or more, the acid is strong.
Examples:
Strong: HClO3, H2SO4
Weak: HClO, H2CO3

39. Net Ionic Equations for Acids and Bases
Polyprotic acids – in the second and subsequent ionizations, acids are ALWAYS weak.
Bases – Hydroxides of alkali and alkaline earth metals, except Be, are STRONG bases. All others are weak.
Salts – written in ionic form if soluble, and undissociated form if insoluble
Oxides – always written in molecular form
Gases – always written in molecular form

40. pH Concept
Expressing [H+] in molarity is cumbersome, so Sorensen proposed the pH scale
Range: 0 – 14

42. Calculating pH pH is the negative logarithm of the [H+] pH = -log[H+]
pOH is the negative logarithm of the [OH-].
pOH = -log [OH-]
Neutral solution has a pOH of 7 and a pH of 7
For all solutions, pOH + pH = 14

43. Calculating Molarity Molarity can be calculated from a pH or pOH
[OH-] = 10-pOH [H+] = 10-pH
Use the 10^ or 2nd log button on the calculator

44. Equivalents
An equivalent is the amount of acid (or base) that will give one mole of H+ (or OH-)
1 mole of HCl produces 1 mole of H+
1 mole of H2SO4 produces 2 moles of H+

45. Normality (N)
Concentration expressed as the number of equivalents of H+ or OH- times the molarity of the solution
N = (eq)M
Example:
0.2 M H2SO4  0.4 N H2SO4
0.15 M H3PO4  0.45 N H3PO4

46. Titration
Method used to determine the concentration of a solution

47. Titration
A solution of known concentration (the standard) is added to a measured amount of the solution of unknown concentration until an indicator signals the end point
The point of neutralization is called the equivalence point – the point in which the number of equivalents of acid and base are equal

48. Calculations with Titrations
Equivalents of Acid = NA x VA
Equivalents of Base = NB X VB
At equivalence point
Equivalents of Acid = Equivalents of Base
NA x VA = NB x VB

49. Buffers
Solutions in which the pH remains relatively constant when small amounts of acid or base are added
Made up of a weak acid and its conjugate base or a weak base and its conjugate acid

51. Buffers
Buffer capacity is the amount of acid or base that can be added to a buffer solution before a significant change in pH occurs
2 buffer systems are found in blood and are crucial in maintaining the pH of the body