1. Chapter 14 – Acids, Bases, and pH
Section 1 –Acids and Bases

2. Properties of Acids 1) Aqueous solutions of acids have a sour taste
2) Acids change the color of acid-base indicators
3) Some acids react with active metals and release H2
Ba(s) + H2SO4(aq) -> BaSO4(s) + H2(g)

3. Properties of Acids
4) Acids react with bases to produce salts and water
A “salt” is any ionic compound formed from an acid reacting, not just NaCl

4. 5) Acids conduct electric current
Think “battery acid”
6) React w/ CO32- to form CO2, H2O, and another compound
-2HCl + K2CO3  CO2 + H2O + 2KCl

5. Properties of Bases Aqueous solutions of bases taste bitter
2) bases change the color of acid-base indicators
3) dilute aqueous solutions of bases feel slippery

6. 4) bases react with acids to produce salts and water
5) bases conduct electric current

7. Indicators
Indicators are dyes that change color when exposed to an acid or a base
Lots of different substances can be indicators
phenolphthalein, red cabbage
Litmus is the most common indicator
Acids turn it red; bases turn it blue

8. Defining Acids
An acid is a substance that produces hydronium ions when it dissolves in water

9. A hydronium ion (H3O+) consists of a hydrogen ion attached to a water molecule
HCl + H2O  H3O+ + Cl-
HC2H3O2 + H2O  H3O+ + C2H3O2-

10. Acidic Hydrogen Atoms
Hydronium ions are formed when a hydrogen ion (H+) transfers from an acid to water (H+ + H2O  H3O+)

11. Any hydrogen atom in an acid that can be transferred to water is called an acidic hydrogen
HCl + H2O  H3O+ + Cl-
HC2H3O2 + H2O  H3O+ + C2H3O2-

12. Acidic Hydrogen Atoms
To help distinguish acids from other hydrogen-containing molecules acidic hydrogens are written first in the formula
HCl
H2SO4

13. The number of acidic hydrogens an acid has is different depending on the acid

14. Monoprotic Acids
An acid that can donate only one proton per molecule is a monoprotic acid
HCl + H2O -> H3O+ + Cl-

15. After the HCl donates one proton there are no others for it to donate

16. Polyprotic Acids
An acid that can donate more than one proton per molecule is a polyprotic acid

17. Polyprotic Acids
An acid that can donate two protons per molecule is a diprotic acid
H2SO4 + H2O -> H3O+ + HSO4-
HSO4- + H2O <-> H3O+ + SO42-
After the H2SO4 donates one proton there is still another for it to donate

18. Polyprotic Acids
An acid that can donate three protons per molecule is a triprotic acid
H3PO4 + H2O <-> H3O+ + H2PO4-
H2PO4- + H2O <-> H3O+ + HPO42-
HPO42- + H2O <-> H3O+ + PO43-
After the H3PO4 donates one proton there are still two more for it to donate

19. Acid Ionization
The process of ions forming from a ionic compound is called ionization
Since acids are ionic compounds, the formation of ions from acids is called acid ionization

20. The ability to ionize in water is what gives acids the ability to conduct electricity

21. Common Industrial Acids
Sulfuric Acid
Most commonly produced industrial chemical in the world
Nitric Acid
Phosphoric Acid

22. Hydrochloric Acid Acetic Acid
Concentrated solutions of HCl are referred to as muriatic acid
Acetic Acid
Pure acetic acid is a clear, colorless, pungent-smelling liquid known as glacial acetic acid

23. Defining Bases
A base is a substance that produces hydroxide ions (OH-) when it dissolves in water
There are two ways this can happen: metal hydroxides and some covalent compounds

24. Metal Hydroxides
Metal hydroxides are ionic compounds made of a metal cation and OH-
NaOH  Na+ + OH-
Unlike acids, water doesn’t react with the base – it is simply present when the dissociation occurs. There is no transfer of ions between water and the base.
Acids can have multiple acidic hydrogens; bases can have multiple hydroxide ions
Ca(OH)2, Al(OH)3

25. Ionic Compounds as Bases
A few bases are ionic compounds that produce OH- when they ionize in H2O
The ionization involves the transfer of a H+ from water to the base
NH3 + H2O  NH4+ + OH-
B + H2O  BH+ + OH-
Both produce OH- so both are bases

26. Bases are Electrolytes
Like acids, bases produce ions in water
This makes them good conductors of electricity

27. Anhydrides
Anhydrides are compounds containing oxygen bonded to just one other element; the word anhydride means that they do not contain water
Although they do not fit our previous definitions of acids and bases they still act as acids and bases

28. Anhydrides
Nonmetal oxides react with water to form acids and are called acidic anhydrides
Metal oxides react with water to form bases and are called basic anhydrides

29. Acidic Anhydrides and Acid Rain
CO2 exists naturally in the atmosphere; it reacts with H2O to form carbonic acid
CO2 + H2O  H2CO3
This makes all rain slightly acidic

30. Other chemicals are released as pollutants into the atmosphere from cars, power plants, etc. (SO2, SO3, NO, NO2); they also react with water to form acids
Very acidic rain is called acid rain

31. Basic Anhydrides and Growth
Lime (CaO) is often added to soil to make it less acidic, which is favorable to plant growth
CaO + H2O  Ca(OH)2
Metal oxides like Na2O, K2O, and CaO are also used to make soap; they also react with water to form bases
Most soaps/cleaners are bases because what we need to clean is acidic