1. Acids Lesson 5 Acid Rain & Hydrolysis

2. Acid Rain Acid Rain is caused by acid anhydrides NO 2 N 2 O 4 automobile pollution SO 2 SO 3 coal & smelter pollution SO 3 +H 2 O→H 2 SO 4(aq) Rain Acid Rain has pH < 5

3. Normal Rain has pH = 6 due to dissolved CO 2 CO 2 +H 2 O→H 2 CO 3 Acid rain dissolves metal, limestone, concrete structures. Acid rain decreases the pH of lakes and causes toxic metals to leach into them.

4. Hydrolysis of Salts 1.Neutral Salts HCl+NaOH→NaCl +HOH strong acidstrong baseneutral salt When the acid and base parents are both strong the salt is always neutral. NaCl Consider the acid and base that makes NaCl

5. A neutral salt will dissociate in water. NaCl → Na + +Cl - Cross off ions from strong parents that are neutral. no ions hydrolyze- neutral

8. Hydrolysis of Salts 2.Basic Salts NaCN +HOHHCN+NaOH→ weak acidstrong basebasic salt ConsiderNaCNConsider the acid and base that makes NaCN

9. A basic salt will first dissociate in water NaCN → Na + +CN - Na + neutral CN - base. CN - +H 2 O ⇄ HCN+OH - Hydrolysis

10. Hydrolysis of Salts 3.Acidic Salts ConsiderNH 4 Cl →NH 4 ClHCl+NH 3 strong acidweak baseacid salt

11. NH 4 Cl → NH 4 + +Cl - positive ion- acid Cl - neutral NH 4 + acid NH 4 + +H 2 O ⇄ H 3 O + +NH 3 Hydrolysis

12. 4.Acidic Salts acid saltweak basestrong acid →FeCl 3 +3HOH3HCl+Fe(OH) 3 ConsiderFeCl 3

13. Fe 3+ OH - H2OH2O H2OH2O H2OH2O H2OH2O H2OH2O H2OH2O

14. Fe 3+ OH - H2OH2O H2OH2O H2OH2O H2OH2O H2OH2O

15. FeCl 3 → Fe 3+ +3Cl - Fe(H 2 O) 6 3+ ⇄ H + +Fe(H 2 O) 5 (OH) 2+ Look for the reaction on the acid chart! positive ion - acid Hydrolysis- when the positive or negative ion in a salt reacts with water as an acid or base.