Post on 03-Jan-2016
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AcidsLesson 6
Acid Rain & Hydrolysis
Acid Rain
The cause of Acid Rain is the release of acid anhydrides into the environment.
Acid Anhydrides are nonmetal oxides. NO2 N2O4 automobile pollution
SO2 SO3 coal & smelter pollution
SO3 + H2O → H2SO4(aq) Rain
Acid Rain has pH < 5
Normal Rain has pH = 6 due to dissolved CO2
CO2 + H2O → H2CO3
Acid rain dissolves metal, limestone, concrete structures. Acid rain decreases the pH of lakes and causes toxic metals to leach into them.
Hydrolysis of Salts Salts can be acidic, basic, or neutral. 1. Neutral Salts Consider NaCl The neutralization equation used to produce NaCl will tell us what kind of salt it is.
Hydrolysis of Salts Salts can be acidic, basic, or neutral. 1. Neutral Salts Consider NaCl The neutralization equation used to produce NaCl will tell us what kind of salt it is.
→ NaCl + HOH
Hydrolysis of Salts Salts can be acidic, basic, or neutral. 1. Neutral Salts Consider NaCl The neutralization equation used to produce NaCl will tell us what kind of salt it is.
H + OH → NaCl + HOH
Hydrolysis of Salts Salts can be acidic, basic, or neutral. 1. Neutral Salts Consider NaCl The neutralization equation used to produce NaCl will tell us what kind of salt it is.
HCl + NaOH → NaCl + HOH
Hydrolysis of Salts Salts can be acidic, basic, or neutral. 1. Neutral Salts Consider NaCl The neutralization equation used to produce NaCl will tell us what kind of salt it is.
HCl + NaOH → NaCl + HOH
strong acid strong base neutral salt
Hydrolysis of Salts Salts can be acidic, basic, or neutral. 1. Neutral Salts Consider NaCl The neutralization equation used to produce NaCl will tell us what kind of salt it is.
HCl + NaOH → NaCl + 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.
NaCl → Na+ + Cl-
Cross off the both ions that come from strong parents as they do not hydrolyze or react further with water- they are neutral.
no ions to hydrolyze- neutral
Hydrolysis of Salts Salts can be acidic, basic, or neutral. 2. Basic Salts Consider NaCN
Hydrolysis of Salts Salts can be acidic, basic, or neutral. 2. Basic Salts Consider NaCN
H + OH → NaCN + HOH
Hydrolysis of Salts Salts can be acidic, basic, or neutral. 2. Basic Salts Consider NaCN
HCN + NaOH → NaCN + HOH
Hydrolysis of Salts Salts can be acidic, basic, or neutral. 2. Basic Salts Consider NaCN
HCN + NaOH → NaCN + HOH
weak acid strong base basic salt
Hydrolysis of Salts Salts can be acidic, basic, or neutral. 2. Basic Salts Consider NaCN
HCN + NaOH → NaCN + HOH
weak acid strong base basic salt
A basic salt will first dissociate in water
NaCN → Na+ + CN-
Cross off the Na+ because it has a strong parent and does not hydrolyze- it is neutral
Then the CN- ion, from the weak parent, will hydrolyze (react with water) as a Bronsted base.
CN- + H2O ⇄ HCN + OH-
negative ion left- basic
Hydrolysis of Salts Salts can be acidic, basic, or neutral. 3. Acidic Salts Consider NH4Cl
→ NH4Cl
Hydrolysis of Salts Salts can be acidic, basic, or neutral. 3. Acidic Salts Consider NH4Cl
HCl + NH3 → NH4Cl
Hydrolysis of Salts Salts can be acidic, basic, or neutral. 3. Acidic Salts Consider NH4Cl
HCl + NH3 → NH4Cl
strong acid weak base acid salt
Hydrolysis of Salts Salts can be acidic, basic, or neutral. 3. Acidic Salts Consider NH4Cl
HCl + NH3 → NH4Cl
strong acid weak base acid salt
An acidic salt will first dissociate in water
NH4Cl → NH4+ + Cl-
Cross off the Cl- because it has a strong parent and does not hydrolyze- it is neutral
Then the NH4+ ion, from the weak parent, will hydrolyze (react with
water) as a Bronsted acid.
NH4+ + H2O ⇄ H3O+ + NH3
positive ion left- acidic
Hydrolysis of Salts Salts can be acidic, basic, or neutral. 4. Acidic Salts Consider FeCl3
3HCl + Fe(OH)3 → FeCl3 + 3HOH
strong acid weak base acid salt
FeCl3 → Fe3+ + 3Cl-
The Fe3+ ion is an acid
Fe(H2O)63+ ⇄ H+ + Fe(H2O)5(OH)2+
You can copy these complex reactions right off the acid chart!
positive ion left- acidic