13/14 Acid–Base and Solubility Equilibria Free Online FlashCards

What do Arrhenius acids and bases produce in water?

An Arrhenius acid produces H₃O⁺ in water, while an Arrhenius base produces OH⁻ in water.

What defines a Brønsted–Lowry acid–base pair?

A Brønsted–Lowry acid donates a proton, and a Brønsted–Lowry base accepts a proton. A conjugate acid–base pair differs by one proton.

What distinguishes Lewis acids from Lewis bases?

A Lewis acid accepts an electron pair, whereas a Lewis base donates an electron pair. In BF₃ + NH₃, BF₃ is the acid and NH₃ is the base.

What relationship connects pH and pOH at 25 °C?

At 25 °C, pH + pOH = 14.00 because Kᵥ = [H₃O⁺][OH⁻] = 1.0 × 10⁻¹⁴.

Why is [OH⁻] ≈ 2C for Ba(OH)₂?

For Ba(OH)₂, [OH⁻] ≈ 2CBa(OH)₂ because each formula unit supplies two hydroxide ions.

How do Kₐ and pKₐ indicate acid strength?

A larger Kₐ means a stronger acid, while a lower pKₐ means a stronger acid because pKₐ = −log Kₐ.

When is the weak-acid approximation [H₃O⁺] ≈ √(KₐC) valid?

For a weak acid of concentration C, [H₃O⁺] ≈ √(KₐC) when ionization is less than about 5% of C.

Why is a sodium acetate solution basic?

Acetate hydrolysis produces OH⁻, so sodium acetate solutions are basic: CH₃CO₂⁻ + H₂O ⇌ CH₃CO₂H + OH⁻.

What equation gives the pH of an acidic buffer?

The Henderson–Hasselbalch equation is pH = pKₐ + log([A⁻]/[HA]). Mole ratios may replace concentration ratios when both species share the solution.

When is an acidic buffer most effective?

A buffer is most effective when [A⁻] = [HA], because then pH = pKₐ. To design a buffer, choose a weak acid with pKₐ near the target pH.

How do equivalence point and endpoint differ?

The equivalence point is reached when stoichiometrically equivalent amounts have reacted. The endpoint is the observed indicator or instrumental signal and should closely match equivalence.

What is true at the half-equivalence point?

At the half-equivalence point of a weak-acid–strong-base titration, [HA] = [A⁻], so the Henderson–Hasselbalch equation gives pH = pKₐ.