week-9 - Makeup Midquarter Exams Wed., Mar 7 5:30-7:20 pm...

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1 Makeup Midquarter Exams Wed., Mar 7 5:30-7:20 pm 1000 McPherson You MUST Sign up in 100 CE Please do so as soon as possible, but no later than Friday, Mar 2. Final Exams for Chem 122 - Mathews 2:30 Class: Thursday, Mar. 15 at 1:30 in (TBA) 6:30 Class: Tuesday, Mar. 13 at 7:30pm in (TBA) Quiz Number 4 – in lecture 15 minutes, 20 pts 1. (4 pts)A salt solution is found to be neutral. Which of following could be the salt(s) used to form the solution? KBr, NH 4 Cl, KCN, or K 2 CO 3 ? 2. (10 pts) Calculate the [OH-] and pH for a solution that is 0.085 M in NaF. K a (HF) = 6.8 x 10 -4 3. (6 pts) How would you rationalize the fact that: a. H 2 S is a stronger acid than H 2 O? b. H 2 SO 4 is a stronger acid than HSO 4 -? 16.5 Strong Acids and Bases Strong Acids Strong Bases 16.6 Weak Acids Calculating K a from pH Using K a to Calculate pH Polyprotic Acids 16.7 Weak Bases Types of Weak Bases 16.8 Relationship Between Ka and Kb 16.9 Acid-Base Properties of Salt Solutions 16.10 Acid-Base Behavior and Chemical Structure Factors That Affect Acid Strength Binary Acids Oxyacids Carboxylic Acids 16.11 Lewis Acids and Bases Hydrolysis of Metal Ions Types of Weak Bases Types of Weak Bases • Bases generally have lone pairs or negative charges in order to attack protons. • Most neutral weak bases contain nitrogen. • Amines are related to ammonia and have one or more N-H bonds replaced with N-C bonds (e.g., CH 3 NH 2 is methylamine). • Anions of weak acids are also weak bases. Example: OCl - is the conjugate base of HOCl (weak acid): ClO - ( aq ) + H 2 O( l ) HClO( aq ) + OH - ( aq ) K b = 3.3 x 10 -7 Relationship Between K Relationship Between K a and K and K b • We need to quantify the relationship between strength of acid and conjugate base. • When two reactions are added to give a third, the equilibrium constant for the third reaction is the product of the equilibrium constants for the first two: Reaction 1 + reaction 2 = reaction 3 has K 1 × K 2 = K 3 . Relationship Between K Relationship Between K a and K and K b • For a conjugate acid-base pair K a × K b = K w • Therefore, the larger the K a , the smaller the K b . That is, the stronger the acid, the weaker the conjugate base. • Taking negative logarithms: p K a + p K b = p K w
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2 Consider the following interesting reaction: HF + CN- = HCN + F- how do we get K = ??? Given K a (HCN) = 6.17 x 10 -16 and K a (HF) = 6.6 x 10 -4 derive K for the above reaction. Acid Acid -Base Properties of Salt Solutions Base Properties of Salt Solutions • Nearly all salts are strong electrolytes.
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week-9 - Makeup Midquarter Exams Wed., Mar 7 5:30-7:20 pm...

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