Acids Lesson 5 Acid Rain Hydrolysis Acid Rain

Acids Lesson 5 Acid Rain & Hydrolysis

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

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

Hydrolysis of Salts 1. Neutral Salts Consider the acid and base that makes Na. Cl HCl + Na. OH → Na. Cl + HOH strong acid strong base neutral salt When the acid and base parents are both strong the salt is always neutral.

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

Hydrolysis of Salts 2. Basic Salts Consider Na. CN HCN + Na. OH weak acid strong base Consider the acid and base that makes Na. CN → Na. CN + basic salt HOH

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

Hydrolysis of Salts 3. Acidic Salts Consider NH 4 Cl HCl + NH 3 strong acid weak base → NH 4 Cl acid salt

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

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

H 2 O Fe 3+ H 2 O OH H 2 O

H 2 O Fe 3+ H 2 O OH H+

Fe. Cl 3 → Fe 3+ Fe(H 2 O)63+ ⇄ positive ion - acid + 3 Cl- H+ + Fe(H 2 O)5(OH)2+ Look for the reaction on the acid chart! Hydrolysis- when the positive or negative ion in a salt reacts with water as an acid or base.