Lesson: Classifying Acids and Bases Based on Dissociation Constants

In this lesson, we will learn how to classify acids and bases as weak or strong based on their dissociation constants.

Worksheet: Classifying Acids and Bases Based on Dissociation Constants • 7 Questions

Q1:

The relative acid strengths of N H 4 + and H C N can be determined by comparing their acid and base dissociation constants, 𝐾 a and 𝐾 b . H C N has a 𝐾 a of 4 . 9 × 1 0 1 0 and N H 3 , the conjugate base of N H 4 + , has a 𝐾 b of 1 . 8 × 1 0 5 . Given that the self-ionization constant of water is 1 . 0 × 1 0 1 4 , which compound is the stronger acid?

Q2:

The odor of vinegar is due to the presence of acetic acid, C H C O H 3 2 , a weak acid. For a solution of acetic acid, which of the following is false?

Q3:

Household ammonia is a solution of the weak base N H 3 in water. For a solution of ammonia, which of the following is false?

Q4:

Which base, C H N H 3 2 or ( C H ) N H 3 2 , is the stronger base at 2 5 C ? The 𝐾 b of C H N H 3 2 at this temperature is 4 . 4 × 1 0 4 and the 𝐾 b of ( C H ) N H 3 2 is 5 . 9 × 1 0 4 .

Q5:

The active ingredient formed by aspirin in the body is salicylic acid, C H O H ( C O H ) 6 4 2 . The carboxyl group ( C O H ) 2 acts as a weak acid. The phenol group (an O H group bonded to an aromatic ring) also acts as an acid but a much weaker acid.

Which one of the following is false for a 0.001 M aqueous solution of salicylic acid?

Q6:

Which is the stronger base, ( C H ) N 3 3 or H B O 2 3 ? The 𝐾 b of ( C H ) N 3 3 is 6 . 3 × 1 0 5 and the 𝐾 a of H B O 3 3 is 5 . 4 × 1 0 . 1 0

Q7:

A 5.16 g sample of N H C l 4 was added to 20.0 mL of 1 . 0 0 M N a O H and the resulting solution diluted to 0.100 L. The 𝐾 b of N H 3 is 1 . 8 × 1 0 5 . Is the solution acidic, neutral, or basic?

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