Acids and Bases Cheat Sheet

This cheat sheet covers fundamental concepts of acids and bases, including conjugate pairs, dissociation constants (Ka and Kb), pH/pOH calculations, and the behavior of salts in solution. It provides formulas and examples for calculating concentrations and pH/pOH for various scenarios.

Core Principles

• Acids donate protons (H+), bases accept protons.
• Conjugate acid-base pairs differ by one proton.
• Strong acids/bases dissociate completely; weak ones do not.
• Ka and Kb quantify acid and base strength, respectively.
• pH = -log[H+], pOH = -log[OH-], and pH + pOH = 14 at 25°C.
• Kw = [H+][OH-] = 1.0 x 10^-14 at 25°C.
• Salts can be acidic, basic, or neutral depending on their parent acid and base.
• Weak acids/bases require equilibrium calculations (ICE tables).
• Percent dissociation indicates the extent of ionization.

Action Steps

• Identify the acid and its conjugate base, or the base and its conjugate acid.
• Determine if the substance is a strong or weak acid/base.
• Use ICE tables for weak acids/bases to find equilibrium concentrations.
• Calculate [H+] or [OH-] using Ka, Kb, or Kw.
• Convert [H+] or [OH-] to pH or pOH using logarithmic formulas.
• For salts, determine if they will produce acidic or basic solutions based on their parent acid/base.

Formulas

• pH = -log[H+]
• pOH = -log[OH-]
• Kw = [H+][OH-]
• pH + pOH = 14
• Ka = [H+][A-]/[HA]
• Kb = [BH+][OH-]/[B]
• Percent Dissociation = ([H+]/[HA]₀) * 100%

Key Terms

• Acid: A substance that donates protons (H+) in a solution.
• Base: A substance that accepts protons (H+) or donates hydroxide ions (OH-) in a solution.
• Conjugate Acid-Base Pair: Two species that differ by a single proton (H+).
• Ka: Acid dissociation constant; measures the strength of a weak acid.
• Kb: Base dissociation constant; measures the strength of a weak base.
• pH: A measure of the acidity or alkalinity of a solution, based on the hydrogen ion concentration.
• pOH: A measure of the basicity or alkalinity of a solution, based on the hydroxide ion concentration.
• Kw: The ion product constant for water; Kw = [H+][OH-].

Real World Examples

• Vinegar (acetic acid): Used in cooking and cleaning; its acidity is quantified by Ka.
• Ammonia: A common weak base used in cleaning products and industrial processes; its strength is measured by Kb.
• Stomach acid (HCl): A strong acid crucial for digestion; its high concentration leads to a low pH.
• Blood: Maintained at a specific pH range (around 7.4) by buffer systems, crucial for biological functions.
• Soaps and detergents: Often contain basic components that help in cleaning by saponifying fats.

Timeline

• 1834: Jöns Jacob Berzelius introduces the terms 'acid' and 'base'.
• 1884: Svante Arrhenius proposes the first theory of acids and bases, defining them by their behavior in water.
• 1923: Johannes Brønsted and Thomas Lowry independently develop the Brønsted-Lowry acid-base theory, focusing on proton transfer.
• 1923: G.N. Lewis proposes a broader definition of acids and bases based on electron pair donation and acceptance.
• 1909: Søren Sørensen introduces the pH scale for measuring acidity.

People

• Svante Arrhenius: Proposed the Arrhenius theory of acids and bases.
• Johannes Brønsted: Co-developed the Brønsted-Lowry acid-base theory (proton transfer).
• Thomas Lowry: Co-developed the Brønsted-Lowry acid-base theory (proton transfer).
• G.N. Lewis: Proposed the Lewis acid-base theory (electron pair acceptance/donation).
• Søren Sørensen: Invented the pH scale.