Acids and Bases: Identify and Classify

• Conjugate base is the particle that remains when an acid has donated a hydrogen ion.
• Properties of bases include: bitter taste, caustic nature, and a pH greater than 7.

Identifying Acids, Bases, Conjugate Acids, and Conjugate Bases

• NH3 (aq) + H2O (l) → NH4+ (aq) + OH- (aq): NH3 is the base, H2O is the acid, NH4+ is the conjugate acid, and OH- is the conjugate base.
• HCOOH(aq) + H2O → H3O+(aq) + HCOO-(aq): HCOOH is the acid, H2O is the base, H3O+ is the conjugate acid, and HCOO- is the conjugate base.
• C6H5NH2 (aq) + H2O (l) → C6H5NH3+ (aq) + OH- (aq): C6H5NH2 is the base, H2O is the acid, C6H5NH3+ is the conjugate acid, and OH- is the conjugate base.
• H2SO4 + H2O → HSO4- + H3O+: H2SO4 is the acid, H2O is the base, HSO4- is the conjugate base, and H3O+ is the conjugate acid.

Classifying Acids

• HCOOH is monoprotic.
• HBr is monoprotic.
• H2SO3 is diprotic.
• H3PO4 is triprotic.

Neutralization Reactions

• H2SO4 (aq) + 2NaOH (aq) → Na2SO4 + 2H2O
• 2HNO3 (aq) + Ca(OH)2 (aq) → Ca(NO3)2 + 2H2O
• 2HF (aq) + Ba(OH)2 (aq) → BaF2 + 2H2O
• H3PO4 (aq) + NaOH (aq) → Na3PO4 (aq) + H2O (l): H3PO4 is the acid, NaOH is the base, Na3PO4 is the salt, and H2O is water.

Calculations

• Given [H+] = 1 × 10^-6 M, the pH = 6.0.
• Given [H+] = 7.2 × 10^-9 M, the pH = 8.14.
• Given [H+] = 3.5 × 10^-2 M, the [OH-] = 2.9 × 10^-13 M.
• pH of a 0.5 M HClO3 solution: pH = 0.3
• pH of a 2.0 M HC2H3O2 solution with Ka = 1.8 x 10^-5: pH = 2.22
• Volume of 3.5 M Ca(OH)2 required to neutralize 38 mL of 2.3 M HCl: VB = 12.5 mL

Graph Analysis

• The graph illustrates the titration of a strong acid/base with a strong/weak acid/base.
• Acid was was added from the buret
• The volume required to reach the equivalence point is 10 mL.
• The pH at the equivalence point is 7.
• The concentration of base B(OH)2 is 1.5M

Strong vs Weak Acids

• Strong acids dissociate completely into H+ and A-.
• Weak acids dissociate slightly into H+ and A-.

Acid-Base Indicators

• At a pH of 8.5, phenolphthalein would be pink.
• Litmus and Methyl Orange indicator is red at pH 4.3.
• The pH range where bromothymol-blue is yellow, blue, and green is 6-7.6.

Definitions

• Analyte: The substance being analyzed in a titration.
• Titrant: The solution of known concentration added during a titration.
• Equivalence Point: The point in a titration where the amount of titrant added is stoichiometrically equivalent to the analyte.
• End Point: The point in a titration where a visible change (like color change) indicates the equivalence point has been reached.