Reading notes for Chapter 17, 18, & 19 in AP Chemistry.

Chapter 17 and Chapter 18 Reading Notes

I Various Theories of Acids and Bases

1) Know the definitions of an acid and a base using

A) Arrhenius Theory

B) Bronsted Theory

C) Lewis Theory

II Bronsted Theory

1) Molecular Structure ( Think about the Lewis structure of a substance and be able to explain the following in terms of bond strength, dipole moment, polarizability etc.)

· What is an acid, what is a base?

· Why can a substance be amphoteric or amphiprotic?

· What is true of acid strength when considering the subsequent steps of the dissociation of a polyprotic acid. (Consider the strength of the bond between the H ion and the anion to which it is attached.)

· What is the relationship between the strength of an acid and it conjugate base. (Consider the strength of the bond between the H ion and the anion to which it is attached.)

2) Equilibrium constants for acids and bases.

· spend time looking at the bulleted statements on p. 807 of your text book.

· relate the magnitude of the Ka or Kb to the acid and base strength, and whether the system is reactant or product favored

· write the equilibrium constant expression for acid or base equilibria with water as the solvent

A) Find the pH, pOH, hydronium ion concentration, and hydroxide concentration for a .100 Molar Benzoic acid solution. (Look at p. 808 for the Ka of benzoic acid)

B) Find the Ka of lactic acid if a .100 Molar solution has a pH of 2.43. (Answer is on p. 819)

3) Conjugate Acid Base Equilibria

A) Autoionization

H₂O (l) + H₂O (l) <===> H₃O⁺ (aq) + OH^- (aq) K_w = 1.00 x 10^-14

Based on this equilibrium find the [ H₃O⁺ ], [OH^- ], and pH of water.

note the relationship [ H₃O⁺ ] [OH^- ] = 1.00 x 10^-14 works for all aqueous solutions.

B) The product of the equilibrium constants for a conjugate acid base pair is the K_w .

K_a K_b = K_w

Show how the equilibria for HF support this idea. Look at p. 808 for the value of the constants.

III Hydrolysis of Salts

1) Categorize each of the following acids and bases as strong or weak. Do the same for their conjugate.

Substance	Acid or Base?	Strong or Weak?	Formula of Conjugate	Conjugate Acid or Base?	Strong or Weak?
HCl
NaOH
HC2H3O2
NaAc
NH3

2)Show the equilibrium. Find the pH of each of the following solutions

A) Cation Hydrolysis - Acidic Solutions

Add .100 moles of NH₄Cl to enough water to make 1.00 liter of solution

B) Anion Hydrolysis - Basic Solutions

Add .100 moles of NaC₂H₃O₂ to enough water to make 1.00 liter of solution.

3) Buffer Solutions - Solutions which resist a change in pH. These solutions are made from substances which are weak conjugate acid base pairs. (You should note this is an application of the common ion effect and can be analyzed qualitatively using LeChatelier’s Principle.)

A) .500 mole of sodium acetate is added to 1.00 liter of .500 molar Acetic acid. Write the equilibrium and find the pH.

B) .100 moles of HCl is added to this buffer solution. Show the resulting reaction between the hydrochloric acid and the buffer. Show the buffer equilibria and find the pH of the resulting solution.

V) Acid Base Titration and Titration Curves.

1) Review the process of titration as it applies to finding an unknown concentration of an acid or base. Consider the experimental technique and how to minimize systematic error in the procedure of the lab experiment. (Things such as washing the buret out three times with the standard solution, filling the tip of the buret etc.) Also know the vocabulary. End point, Equivalence point, Standard Solution, Titrant, buret, aliquot.

2) Titration Curves - Graphs of pH versus ml of titrant added.

A) Describe the procedure for attaining the data necessary to construct the titration curve.

For each system below

a) Show the reaction which occurs between the acid and base

b) Show the equilibrium which dominates at the equivalence point

c) Predict the approximate pH at the equivalence point and then calculate the pH quantitatively.

d) Sketch a titration curve for the system

B) Strong Acid - Strong Base HCl & NaOH

a) Reaction

b) Equilibrium

c) approximate pH is _____________

calculated pH

d)

pH
		ml of titrant

C) Strong Acid- Weak Base HCl NH₃

a) Reaction

b) Equilibrium

c) approximate pH is _____________

calculated pH

d)

pH
		ml of titrant

D) Weak Acid - Strong Base HC₂H₃O₂ , NaOH

a) Reaction

b) Equilibrium

c) approximate pH is _____________

calculated pH

d)

pH
		ml of titrant

Bits and Pieces, Do the problem sets, Don’t skip any of the assigned problems as I assigned the minimum.

Chapter 19

VI Solubility Equilibrium This is not a new set of Theories, just another application of the equilibrium concepts.

1) Define solubility and how it relates to a saturated solution. What are the various units in which solubility is measured?

2) The Solubility Product, K_sp, is the variable representing the equilibrium constant for the formation of precipitates or other saturated solutions. (Yes Eric and Aaron water is the solvent unless stated otherwise.) Remember solids and liquids are not included in the equilibrium constant expression, mass action expression.

A) The Ksp of CaF₂ is 3.9 x 10 ^-11.

a)Write the equilibrium which exists in a saturated solution. Find the Molar Solubility of CaF₂. (in water)

B) Reaction Quotient

If .00160 moles of Ca(NO₃)₂ solid is mixed into 1.00 liter of .00200 Molar NaF (aq) will a precipitate form?

Show the double- displacement reaction which creates the lead (II) chloride.

Show the equilibrium which is created in a saturated solution of lead (II) chloride and predict whether the precipitate will form.

2) Common Ion Effect - Application of Le Chatelier’s Principle.

A substance is less soluble in a solution which contains a common ion than in water.

A) Find the solubility of CaF₂ solid in a 1.00 Molar NaF. Compare your answer with 1A above.