Acids and Bases

Properties of Acids and Bases

Properties of Acids and Bases https://www.youtube.com/watch?v=UNLz8ApXjBI

Properties of Acids and Bases Sour to taste Reactive Corrosive Electrolytes Bitter to taste Slippery Corrosive Electrolytes

Acid Base Nomenclature

Acid Nomenclature Rule 1: Acids based on anions whose name ends in –ide have associated acids that have the hydro- prefix and –ic ending

Acid Nomenclature Rule 2: Acids based on anions whose name ends in –ate have associated acids that have an –ic ending

Acid Nomenclature Rule 3: Acids based on anions whose names end in –ite have associated acids that have an –ous ending

Naming Bases You can already do this Examples: Ca(OH)2 NH3

3 Models of Acid- Base Behavior

Arrhenius Model Base Acid a substance that increases the concentration of H+ in aqueous solution HCl(aq)  H+ + Cl- a substance that increases the concentration of OH- in aqueous solution NaOH(aq)  Na+ + OH-

Bronsted-Lowry Model molecule or ion that donates a proton (H+) Acid Base molecule or ion that donates a proton (H+) molecule or ion that accepts a proton (H+)

Amphoteric (amphiprotic) Substance that can act as an acid or base

Lewis Model atom, ion, or molecule that accepts an electron pair Acid Base atom, ion, or molecule that accepts an electron pair atom, ion, or molecule that donates an electron pair

The pH Scale

Self-Ionization of water Two water molecules produce a hydronium ion and hydroxide ion by transfer of a proton Kw = [H3O+][OH-] = 1.0x10-14

Neutral, Basic, Acidic? Neutral: when [H3O+] = [OH-] Basic: [H3O+] < [OH-] Acidic: [H3O+] > [OH-]

Neutral, Basic, Acidic?

The pH Scale Ranges from 0-14 Less than 7 is acidic, 7 is neutral, more than 7 is basic

The pH Scale -The lower the pH, the higher the concentration of H+ Ranges from 0-14 pH= -log [H3O+] pOH = -log [OH-] pH + pOH= 14

The pH Scale Important Formulas: pH= -log [H+] pOH = -log [OH-] pH + pOH= 14 [H+] = 10-pH [OH-] = 10-pOH

The pH Scale

pH of Strong Acids and Bases Strong Acids completely ionize Calculate pH from [H+]

pH of Strong Acids and Bases Strong Bases completely ionize Calculate the pOH from the concentration of [OH-], then calculate pH

Titrations

Neutralization Reactions Acid + Base  Salt + Water Salt = cation of base plus anion of acid

Titrations Titration is the controlled addition and measurement of the amount of solution of known concentration required to react completely with a measured amount of a solution of unknown concentration

Titrations Equivalence point - the point at which two solutions used in titration are present in chemically equivalent amounts - In an acid –base titration mole H+ = mole OH-

Titrations Acid –Base indicators - compounds whose colors are sensitive to pH

Titrations End point = the point in a titration at which an indicator changes color.

Titrations Acid –Base indicators https://www.youtube.com/watch?v=UNLz8ApXjBI

Titrations

Titrations

Determining the molarity of unknown solution by titration Titrations Determining the molarity of unknown solution by titration 1. Write the rxn 2. determine moles neutralized using stoich 3. Divide moles by volume of unknown to calculate molarity

Titrations In a titration 27.4mL of 0.0154M Ba(OH)2 is added to a 20.0mL sample of HCl solution of unknown concentration. What is the molarity of the acid solution?