Q: What is the relationship between $$K_a$$ and $$K_b$$ for a conjugate acid-base pair at 25°C?

$$K_a \times K_b = 1.0 \times 10$$^{-14}$$

Question 1

Which of the following statements best describes the Brønsted-Lowry definition of acids and bases?

Accepted Answer

An acid is a proton donor, and a base is a proton acceptor.

Question 2

A 0.10 M solution of formic acid (HCOOH) has a pH of 2.38 at 25°C. What is the acid dissociation constant ($$K_a) $$for formic acid at this temperature?

Accepted Answer

$$K_a = 1.7 	imes 10$$^{-4}$$

Question 3

Which of the following solutions will have the lowest pH?

Accepted Answer

0.10 M HCl

Question 4

What is the pH of a solution with $$[H^+] = 3.2 	imes 10$$^{-5}$$ M?

Accepted Answer

pH = 4.49

Question 5

Which of the following is an example of an amphiprotic substance?

Accepted Answer

H2O

Question 6

A solution is prepared by mixing 250.0 mL of 0.123 M Ba(OH)2 and 120.0 mL of 0.456 M KOH. What is the final concentration of OH- ions in the mixture? (Assume volumes are additive.)

Accepted Answer

$$[OH^-] = 0.234 M$$

Question 7

Which of the following salts will produce a basic solution when dissolved in water?

Accepted Answer

Na2CO3

Question 8

Which factor most strongly influences the acid strength of binary acids within a group in the periodic table?

Accepted Answer

Bond strength

Question 9

Which of the following is a Lewis acid?

Accepted Answer

BF3

Question 10

What is the relationship between $$K_a$$ and $$K_b$$ for a conjugate acid-base pair at 25°C?

Accepted Answer

$$K_a 	imes K_b = 1.0 	imes 10$$^{-14}$$

Question 11

Which of the following statements about polyprotic acids is correct?

Accepted Answer

The first proton is always removed more easily than the second.

Question 12

Which of the following best explains why carboxylic acids are generally stronger acids than alcohols?

Accepted Answer

The carboxylate anion is stabilized by resonance.

Question 13

A solution has a pOH of 3.5. What is its pH at 25°C?

Accepted Answer

pH = 10.5

Question 14

Which of the following is NOT a property of a strong acid?

Accepted Answer

Its conjugate base is a strong base.

Question 15

Which of the following best describes the behavior of transition metal cations in aqueous solution?

Accepted Answer

They form acidic solutions due to the hydrolysis of hydrated cations.

Question 16

Which of the following is the correct expression for the acid dissociation constant ($$K_a) $$for acetic acid ($$CH_3COOH$$)?

Accepted Answer

$$K_a = \frac{[CH_3COO^-][H_3O^+]}{[CH_3COOH]}$$

Question 17

Which of the following best describes the effect of increasing the number of oxygen atoms in an oxyacid?

Accepted Answer

The acid strength increases.

Question 18

Which of the following is a correct statement about the pH scale?

Accepted Answer

A solution with pH 3 has a higher $$[H^+]$$ than a solution with pH 7.

Question 19

Which of the following is a real-life application of acid-base chemistry in medicine?

Accepted Answer

Using sodium bicarbonate to neutralize excess stomach acid.

Acid-Base Equilibria: Structured Study Notes for GOB Chemistry

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