🔬 Acids and Bases — Definitions, Strength, and pH Strategy

Acids and bases appear throughout the DAT in general chemistry, biochemistry, and biology. Expect questions on pH calculations, conjugate pairs, strength, and molecular identification. This blog breaks it all down with rules, visuals, and DAT-focused strategies.

🧪 Acid-Base Definitions

Definition	Acid	Base
Arrhenius	Produces H⁺ in solution	Produces OH⁻ in solution
Brønsted-Lowry	Donates H⁺	Accepts H⁺
Lewis	Electron pair acceptor	Electron pair donor

📌 DAT Tip: Brønsted-Lowry is the most commonly tested on the exam.

💪 Strong vs. Weak Acids/Bases

Strong Acids (completely dissociate):

• HCl, HBr, HI

• HNO₃, HClO₄, H₂SO₄

Weak Acids (partial dissociation):

• HF, CH₃COOH, HCN

Strong Bases:

• Group 1 & 2 hydroxides (e.g., NaOH, Ca(OH)₂)

🧠 Conjugate Acid-Base Pairs

• When an acid donates a proton → forms its conjugate base

• When a base accepts a proton → forms its conjugate acid

Example:

NH₃ (base) + H⁺ → NH₄⁺ (conjugate acid)

📌 The stronger the acid, the weaker its conjugate base.

📊 pH, pOH, and [H⁺]/[OH⁻] Relationships

Quantity	Formula
pH	–log[H⁺]
pOH	–log[OH⁻]
pH + pOH	= 14 (at 25°C)
[H⁺]	10–pH
[OH⁻]	10–pOH

🧪 Ka and Kb (Acid/Base Strength Constants)

• Ka: Measures acid strength

• Kb: Measures base strength

• pKa + pKb = 14

• The larger the Ka/Kb → the stronger the acid/base

🧠 DAT Question Styles

• “Which is the conjugate base of HF?”

• “Which of the following is a Lewis base?”

• “Calculate the pH of a 0.01 M HCl solution.”

• “Rank acids from strongest to weakest.”

🎯 Call to Action

Join King of the Curve to:

• Practice pH/pOH & Ka/Kb problems

• Visualize acid-base interactions

• Learn with adaptive quizzes & flashcards

• Compete in multiplayer DAT chemistry games

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