Southeast Missouri State University
CH186
General Chemistry II

Study Guide
Acid-Base Chemistry

What should you know about Acid-Base Chemistry?

Important Terms and Concepts:
          Bronsted-Lowry acid           Bronsted-Lowry base             conjugate acid-base pair
          strong acid                            weak acid                                 strong base        
          weak base                             dissociation of water                ion-product of water
          pH                                          pOH                                         pK_w
          acid dissociation constant   base dissociation constant      percent dissociation
          monoprotic acid                   diprotic acid                              common-ion effect
          buffer                                    neutralization                           titration curve
          equivalence point                 Lewis acid                                 Lewis base

Key Equations:
     pH = -log[H₃O⁺]   
     pOH = -log[OH^-]
     K_w = [H₃O⁺][OH^-] (K_w = 1.0 x 10^-14 at 25°C) (for any aqueous solution)
     pH + pOH = pK_w (pK_w = 14.00 at 25°C) (for any aqueous solution)
     K_a = [H₃O⁺][A^-]/[HA] (for weak acid HA)
     K_b = [HB⁺][OH^-]/[B] (for weak base B)
     K_aK_b = K_w (for a conjugate acid-base pair)
     [H₃O⁺] = K_a[acid]/[conjugate base] (for a buffer solution)
     pH = pK_a - log([acid]/[conjugate base]) (for a buffer solution)

Be able to:

• Define acids and bases according to the Bronsted-Lowry and Lewis theories
• Write acid-base reactions according to the Bronsted-Lowry theory and identify Bronsted-Lowry conjugate acid-base pairs.  Be able to write the formulas for the conjugate acids and bases for given substances and ions
• Identify Lewis acids and bases given the chemical equation for an acid-base reaction
• Write the ion-product constant for the dissociation of water, and use this constant to calculate [H₃O⁺] and [OH^-] in aqueous solutions given relevant information about the system
• Explain what is meant by the pH scale, and calculate pH from knowledge of [H₃O⁺] or [OH^-]
• Calculate [H₃O⁺] from pH, and [OH^-] from pOH
• Classify solutions as acidic, basic, and neutral from knowledge of pH, pOH, [H₃O⁺] and [OH^-]
• Define and explain what is meant by the terms strong and weak as applied to acids and bases
• Understand the relationship between the relative strength of an acid and the strength of its conjugate base
• Know the six common strong acids and the strong bases
• Calculate [H₃O⁺], [OH^-], pH and pOH for strong acid solutions and strong base solutions
• Given a weak acid or weak base, write a chemical equation to represent its dissociation in water and set up the expression for its dissociation constant
• Given the initial concentration, pH or pOH of the solution, calculate the dissociation constant for a weak acid or weak base
• Given the initial concentration of a weak acid or weak base in water and the dissociation constant (K_a and K_b ), calculate the concentrations of all solution species at equilibrium, the pH, the pOH, and percent dissociation
• Predict whether aqueous salt solutions are acidic, basic, or neutral
• Understand the relationship between acid-base behavior and chemical structure
• Calculate K_a for an acidic cation or K_b for a basic anion from the dissociation constant of the conjugate base or acid
• Write the chemical equation for a neutralization reaction between an acid and a base
• Understand and explain the common ion effect and how it effects the percent dissociation of weak acids and bases
• Given the concentrations of a weak acid (or weak base) and its salt in solution and the ionization constant of the acid (or base), calculate the percent ionization of the weak acid and the pH of the solution
• Recognize buffer solutions when given the solutes for a solution that contains a weak acid and a salt that contains its conjugate base, or a weak base and a salt that contains its conjugate acid
• Calculate the pH of a buffer solution given the concentrations of the buffer components in solution (or the means to calculate the concentrations) and the dissociation constant of the acidic component
• Calculate the solution pH of a buffer following addition of a known amount of strong acid or strong base to the buffer solution
• Calculate the pH of the solution that results from mixing a specified amount an acid solution with a specified amount of a base solution
• Understand, why the pH is 7 at the equivalence point of a strong acid-strong base reaction.

Updated on 03/08/07

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