Acids, Bases & Buffers

• The three acid-base theories have increasing scope: Arrhenius (aqueous only) $\rightarrow$ Brønsted-Lowry (aqueous + non-aqueous, single ions) $\rightarrow$ Lewis (electron pairs, broadest).
• Strong acids/bases dissociate completely ($\alpha = 1$, one-way $\rightarrow$, no equilibrium); weak acids/bases dissociate partially ($\alpha < 1$, reversible $\rightleftharpoons$, equilibrium exists).
• $pH + pOH = 14$ and $K_a \times K_b = K_w = 10^{-14}$ — both relationships are valid only at 25°C.
• Salt hydrolysis rule: SA + SB = neutral; SA + WB = acidic; WA + SB = basic; WA + WB = calculate.
• A buffer requires $HA \approx A^-$ in comparable amounts — a weak acid alone is NOT a buffer.

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Three Acid-Base Theories — Master Comparison 🔬

⚠️ Exam Trap: All Arrhenius acids/bases are also Brønsted-Lowry, but not vice versa. $NH_3$ is Brønsted-Lowry and Lewis, but NOT Arrhenius. Brønsted-Lowry is contained within Lewis — Lewis is the most inclusive theory.

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Strong vs Weak — Master Comparison 🔬

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Salt Hydrolysis — pH Prediction Table 🧪

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Constants Formula Reference ⚡

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