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Catalyst: Tuesday February 4, 2014

Today’s Objective: -SWBAT use Ka/Kb to predict the strengths of acids and bases

-SWBAT solve problems using Ka and Kb

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Ion Product Example

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Weak Acid (Using Ka)

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Table Talk

• You have a solution of the following acid:HOC6H5 (aq) + H2O (l) H3O+ (aq) + OC6H5

- (aq)• Given that the equilibrium concentrations are

[HOC6H5] = 0.062 M, [H3O+ ] = 1.5 x 10-4 M, and [OC6H5

- ] = 3.1 x 10-5 M, calculate the value of Ka.

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Model

• Calculate the pH of a 0.036 M Nitric Acid (HNO3) solution

HNO3 D H+ + NO3-

Discussion Question

• Calculate the pH of a 0.036 M Sodium Hydroxide solution

NaOH D OH- + Na+

Quicket

Using the table below, which compound would you expect to be the strongest acid?

AB

C

D

Quicket

Using the table below, which compound would you expect to be the strongest acid?

Compound Kb Value

A) Phosphate 5.9 x 10-3

B) Carbonate 2.1 x 10-4

C) Ammonia 1.8 x 10-5

D) Aniline 9.5 x 10-7

Table Talk

• Calculate the Ka for the ammonium ion (Kb = 1.8 x 10-5)

Table Talk

• Consider the following two acids and their ionization constants:

HCOOH Ka = 1.7 x 10-4

HCN Ka = 4.9 x 10-10

Which conjugate base (HCOO- or CN-) is stronger?