CH 102 1st Edition Lecture 15Outline of Current Lecture I. Definitions of Acids and BasesII. What happens?III. Conjugate Acid–Base PairsIV. Strong Acid/Base versus Weak Acid/BaseV. Table of Acid Strengths, Ka and pKaVI. Table of Base Strengths, Kb and pKbVII. Ionization in Polyprotic AcidsCurrent LectureI. Definitions of Acids and Basesa. Arrhenius definition (simplest and most restrictive)i. Acids are substances that when dissolved in water produce a hydronium, H3O+ (hydrogen ion H+).ii. Bases are substances that when dissolved in water produce a hydroxide ion, OH–.b. Brønsted–Lowry definition (based on reactions in water)i. Acids are substances that when dissolved in water donate a proton to a water molecules to generate a hydronium, H3O+.ii. Bases are substances that accept a proton from a water molecule to create a hydroxide ion , OH-.c. Lewis definition (most expansive and based on electron donors and acceptors)These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.i. Acids are substances that accept or need an electron pair.ii. Bases are substances that donate an electron pair to another substance.II. What happens?a. When you add an acid to water i. Hydronium ions are formedii. the pH is low and the solution is acidicb. When you add the conjugate base of an acid to wateri. Hydroxide ions are formedii. the pH is high and the solution is basicc. When you add a base to wateri. Hydroxide ions are formedii. The pH is high and the solution is basicd. When you add the conjugate acid of a base to wateri. Hydronium ions are formedii. The pH is low and the solution is acidicIII. Conjugate Acid–Base Pairsa. In a Brønsted–Lowry acid–base reaction, b. the original base becomes a conjugate acid in the reverse reaction;c. the original acid becomes a conjugate base in the reverse process.d. Each reactant and the product it becomes is called a conjugate pair.e.IV. Strong Acid/Base versus Weak Acid/Basea. A strong acid is a strong electrolyte.i. Complete or near complete ionization of acid molecule in waterb. A weak acid is a weak electrolyte.i. Only a small percentage or partial ionization of the acid molecule in waterii. An equilibrium ( ⇌ ) is established.c. A strong base is a strong electrolyte.i. Complete or near complete ionization of base molecule in waterii. Produces OH– ions, either through dissociation or reaction with waterd. A weak base is a weak electrolyte.i. Only a small percentage or partial ionization of the base molecule in waterii. Produces OH– ions, either through dissociation or reaction with wateriii. An equilibrium ( ⇌ ) is established.V. Table of Acid Strengths, Ka and pKaa.VI. Table of Base Strengths, Kb and pKba.VII. Ionization in Polyprotic Acidsa. Because polyprotic acids ionize in steps, each H has a separate Ka value.i. Ka1 > Ka2 > Ka3b. Generally, the difference in Ka values is great enough so that the second ionization does not happen to a large enough extent to affect the pH.i. Most pH problems just do first ionization.ii. [A2−] = Ka2 as long as the second ionization is
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