Acids and Bases

Arrhenius Acids and Bases Arrhenius acid: Break apart (dissociate) to yield hydrogen ions (H+) in water (aqueous) solutions HCl → H+ + Cl- Arrhenius base: Break apart (dissociate) to yield hydroxide ions (OH-) in water (aqueous) solutions NaOH → Na+ + OH-

Naming Acids and Bases Acids: Remember this chart??? Anion Ending Acid Name -ide hydro-(stem)-ic acid -ite (stem)-ous acid -ate (stem)-ic acid Bases: cation name + hydroxide

Naming Acids Name the following acids: H2CrO4 HF H2CO3 HClO2 CH3COOH Anion Ending Acid Name -ide hydro-(stem)-ic acid -ite (stem)-ous acid -ate (stem)-ic acid

Naming Bases Name the following bases: Ba(OH)2 KOH Al(OH)3 Cation name + hydroxide

More Naming Practice H3PO4 Nitrous acid Mg(OH)2 Hydrobromic acid Name the following acids/bases or write their formula: H3PO4 Nitrous acid Mg(OH)2 Hydrobromic acid Lithium hydroxide H2S Anion Ending Acid Name -ide hydro-(stem)-ic acid -ite (stem)-ous acid -ate (stem)-ic acid

The pH Scale

The pH scale Acidic solution: pH < 7.0 Neutral solution: pH = 7.0 Basic solution: pH > 7.0 Neutral ACIDIC BASIC pH = Increasing acidity Increasing basicity

[H+] = the hydrogen ion concentration IN MOLARITY pH pH (“potential hydrogen”): a way of expressing the hydrogen ion concentration pH = - log [H+] [H+] = the hydrogen ion concentration IN MOLARITY [H+] = 10-pH

Calculating pH Example pH = - log [H+] What is the pH of a HCl solution in which [H+] = 3.9 x 10-4 M?

Calculating [H+] Example [H+] = 10-pH What is the [H+] of a solution if the pH = 10.8?

The pH Scale - As pH increases, [H+] decreases - As pH decreases, [H+] increases

Calculating pH pH [H+] Acidic Solution pH < 7.0 Neutral Solution Basic Solution pH > 7.0 [H+] > 1 x 10-7 [H+] = 1 x 10-7 [H+] < 1 x 10-7

[OH-] = the hydroxide ion concentration IN MOLARITY pOH Just like pH… pOH (“potential hydroxide”): a way of expressing the hydroxide ion concentration pOH = - log [OH-] [OH-] = the hydroxide ion concentration IN MOLARITY Just like [H+]: [OH-] = 10-pOH pH + pOH = 14

Bronsted-Lowry Acids and Bases Bronsted-Lowry acid: donates a proton (H+) in solutions Bronsted-Lowry base: accepts a proton (H+) in solutions HNO2 + H2O ↔ NO2- + H3O+ B-L acid B-L base

Conjugate Acids and Bases Used in Bronsted-Lowry definition ONLY Conjugate acid: the acid formed when a proton (H+) is added to the base Conjugate base: the base formed when a proton (H+) is removed from the acid HNO2 + H2O ↔ NO2- + H3O+ B-L acid B-L base Conjugate base Conjugate acid