1. Acids
Lesson 5
Acid Rain &
Hydrolysis

4. Normal Rain has pH = 6 due to dissolved CO2
+ H2O
→ H2CO3

5. Acid Rain
Acid Rain is caused by acid anhydrides
NO2
N2O4
automobile pollution
SO2
SO3
coal & smelter pollution
SO3
H2O
→ H2SO4(aq)
Acid Rain has pH < 5
Acid rain dissolves metal, limestone, concrete structures.
Acid rain decreases the pH of lakes and causes toxic metals to leach into them.

6. Hydrolysis of Salts
1. Neutral Salts
Consider the acid and base that makes NaCl
NaCl
HCl
+ NaOH
→ NaCl + HOH
strong acid
strong base
neutral salt
NaCl
→ Na Cl-

7. Hydrolysis of Salts
2. Basic Salts
Consider NaCN
HCN
+ NaOH
→ NaCN + HOH
weak acid
strong base
basic salt

8. A basic salt will first dissociate in water
NaCN
→ Na CN-
neutral
base- negative ions are bases
CN-
+ H2O
⇄ HCN + OH-
Hydrolysis

9. Cross off all bold ions- they do not hydrolyze and are neutral
Acidic

10. Hydrolysis of Salts   
3. Acidic Salts
NH4Cl
HCl
+ NH3
→ NH Cl-
strong acid
weak base
acid salt
positive ions are acids

11. NH4Cl → NH Cl-
positive ion- acid
acid
neutral
+ NH3
NH4+
H2O
⇄ H3O+
Hydrolysis

12. Cross off all bold ions- they do not hydrolyze and are neutral
Remaining amphriprotic ions are acidic
Acidic
Basic

13. NH3 is a weak base

14.   4. Acidic Salts
FeCl3
3HCl
+ Fe(OH)3
→ FeCl3 + 3HOH
strong acid
weak base
acid salt

15. H2O
H2O
H2O
Fe3+
OH-
H2O
H2O
H2O

16. H2O
Hydronium ion
H2O H O
H2O
Fe3+ H+
OH-
H2O
H2O

17. FeCl3
→ Fe Cl-
Look for the reaction on the acid chart!
Fe(H2O)63+ ⇄ H+ + Fe(H2O)5(OH)2+
Hydrolysis- when the positive or negative ion in a salt reacts with water as an acid or base.