Accelerated Chemistry Practice Studio

Unit 7: Bronsted-Lowry Models, pH/pOH Logarithms, Weak Acid Equilibria, Titrations, & Buffers.

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Chemistry Reference Center

Transition (3d)

Select any element cell above to inspect its atomic mass, valence electron count, and molar mass for stoichiometry.

Logarithmic pH & pOH Relationships

pH DefinitionpH = -log₁₀[H⁺] (or -log₁₀[H₃O⁺])

pOH DefinitionpOH = -log₁₀[OH⁻]

Water Autoionization (Kw at 25 °C)[H⁺][OH⁻] = 1.0 × 10⁻¹⁴ | pH + pOH = 14.00

Concentration Inverses[H⁺] = 10^(-pH) | [OH⁻] = 10^(-pOH)

Weak Acid & Weak Base Equilibria

Acid Dissociation Constant (Ka)HA + H₂O ⇌ H₃O⁺ + A⁻ | Ka = [H₃O⁺][A⁻] / [HA]

Approximation Formula[H⁺] ≈ √(Ka × [HA]°) when percent ionization < 5%

Percent IonizationPercent Ionization = ([H⁺]_equilibrium / [HA]°) × 100%

Common Ka Values at 25 °CAcetic acid (CH₃COOH): 1.8 × 10⁻⁵ | Formic acid (HCOOH): 1.8 × 10⁻⁴ | Carbonic acid (H₂CO₃): 4.3 × 10⁻⁷

Titrations & Buffer Systems

Neutralization EquivalenceMoles H⁺ from acid = Moles OH⁻ from base (Ma × Va = Mb × Vb for monoprotic)

Henderson-Hasselbalch EquationpH = pKa + log₁₀([Conjugate Base A⁻] / [Weak Acid HA])

Equivalence Point pHStrong Acid + Strong Base: pH = 7.00. Weak Acid + Strong Base: pH > 7.00 (basic salt).

Storyline Anchor: Ocean Acidification & Calcification

Atmospheric Carbon UptakeCO₂(g) dissolves in oceans forming carbonic acid: CO₂ + H₂O ⇌ H₂CO₃ ⇌ H⁺ + HCO₃⁻

Proton Neutralization of CarbonateExcess H⁺ protonates carbonate ions: H⁺ + CO₃²⁻ ⇌ HCO₃⁻, lowering carbonate saturation required for shell formation.

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