Q: Which of the following best describes the relationship between $$K_a$$ and $$K_b$$ for a conjugate acid-base pair at 25$$^\circC$$?

$$K_a \times K_b = 1.0 \times 10$$^{-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 acetic acid (CH$$_3$$COOH) has a $$K_a of$$ $$1.8 	imes 10$$^{-5}$$. What is the pH of this solution? (Assume x$$ \ll 0.10$$ for the ICE table calculation.)

Accepted Answer

$$pH = 2.72$$

Question 3

Which of the following is NOT a strong acid?

Accepted Answer

HF

Question 4

What is the pH of a solution with $$[OH^-] = 2.5 	imes 10$$^{-3}$$ M at 25$$^\circ$$C?

Accepted Answer

$$pH = 2.60$$

Question 5

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

Accepted Answer

NaF

Question 6

Which of the following best explains why H$$_2SO$_4 is a $$stronger acid than H$$_2SO$_3$$?

Accepted Answer

H$$_2SO$_4$$ has more oxygen atoms, increasing the oxidation state of sulfur and stabilizing the conjugate base.

Question 7

A solution is prepared by mixing 100.0 mL of 0.200 M Ba(OH)$$_2$$ and 100.0 mL of 0.200 M NaOH. What is the final $$[OH^-] in $$the solution?

Accepted Answer

$$0.300 M$$

Question 8

Which of the following is the correct expression for the base dissociation constant ($$K_b) $$for ammonia, NH$$_3$$?

Accepted Answer

$$K_b = \frac{[NH_4$^+][OH^-]}{[NH_3$]}$$

Question 9

Which of the following statements about the autoionization of water is correct?

Accepted Answer

The equilibrium constant $$K_w$$ increases with increasing temperature.

Question 10

Which of the following is a Lewis acid but NOT a Brønsted-Lowry acid?

Accepted Answer

BF$$_3$$

Question 11

A 0.10 M solution of a weak acid HA has a pH of 3.00. What is the percent ionization of HA?

Accepted Answer

1.0%

Question 12

Which of the following factors does NOT increase the strength of a binary acid HX?

Accepted Answer

Decreasing the polarity of the H–X bond

Question 13

Which of the following best describes the relationship between $$K_a$$ and $$K_b$$ for a conjugate acid-base pair at 25$$^\circC$$?

Accepted Answer

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

Question 14

Which of the following is the correct formula for calculating the pH of a solution?

Accepted Answer

$$pH = -\log_{10}[H^+]$$

Question 15

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 16

A solution contains 0.050 M H$$_2CO$_3 ($$carbonic acid). Given $$K_{a1} = 4.3 	imes 10$$^{-7}$$ and K$$_{a2} = 5.6 	imes $$10^{-11}$$, which statement is correct about the pH calculation?

Accepted Answer

Only the first ionization is significant for pH calculation.

Question 17

Which of the following best describes the behavior of a solution of NH$$_4Cl in $$water?

Accepted Answer

The solution is acidic because NH$$_4^+ is $$the conjugate acid of a weak base.

Question 18

Which of the following is a property of bases but NOT acids?

Accepted Answer

They turn phenolphthalein pink.

Question 19

Which of the following is the correct relationship between pH and pOH at 25$$^\circC$$?

Accepted Answer

$$pH + pOH = 14$$

Acid-Base Equilibria and Transition-Metal Complexes: Study Notes for GOB Chemistry

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