Q: Which of the following pairs are conjugate acid-base pairs?

$$\mathrm{NH_4$^+}$$ \text{ and } \mathrm{$$NH_3$$}$

Question 1

Which of the following statements best describes a Brønsted-Lowry acid?

Accepted Answer

A substance that donates a proton ($$\mathrm{H^+}) to $$another molecule or ion.

Question 2

Which of the following pairs are conjugate acid-base pairs?

Accepted Answer

$$\mathrm{NH_4$^+}$$ 	ext{ and } \mathrm{$$NH_3$$}$

Question 3

Which of the following acids is triprotic?

Accepted Answer

$$\mathrm{H_3PO_4}$$

Question 4

A 0.01 M solution of HCl has a pH of:

Accepted Answer

2.0

Question 5

Which of the following statements about acid and base strength is correct?

Accepted Answer

A strong acid has a weak conjugate base.

Question 6

What is the pH of a solution with $$[\mathrm{H_3O^+}] = 3.2 	imes 10$$^{-4}$$\ \mathrm{M}$$?

Accepted Answer

3.49

Question 7

A buffer solution is most effective when:

Accepted Answer

The concentrations of weak acid and its conjugate base are equal.

Question 8

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

Accepted Answer

$$\mathrm{NaCN}$$

Question 9

Calculate the pH of a 0.0032 M NaOH solution.

Accepted Answer

11.51

Question 10

Which of the following best describes the role of water in the following reaction? $$\mathrm{NH_3$} + \mathrm{H_2O} \rightleftharpoons \mathrm{NH_4$^+} + \mathrm{OH^-}$$

Accepted Answer

Water acts as a Brønsted-Lowry acid.

Question 11

A buffer is prepared by mixing 0.100 M acetic acid ($$\mathrm{CH_3COOH}$$, $$pK_a = 4.76) $$and 0.100 M sodium acetate ($$\mathrm{CH_3COONa}). $$What is the pH of the buffer?

Accepted Answer

4.76

Question 12

Which of the following is the correct expression for the acid dissociation constant ($$K_a) $$for acetic acid ($$\mathrm{CH_3COOH}) in $$water?

Accepted Answer

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

Question 13

A 0.200 M solution of a diprotic acid ($$\mathrm{H_2A}) is $$prepared. What is the normality of the solution?

Accepted Answer

0.400 N

Question 14

Which of the following reactions represents the neutralization of hydrochloric acid with sodium hydroxide?

Accepted Answer

$$\mathrm{HCl} + \mathrm{NaOH} \rightarrow \mathrm{NaCl} + \mathrm{H_2O}$$

Question 15

A 5.00 mL sample of vinegar requires 44.5 mL of 0.100 M NaOH to reach the endpoint in a titration. What is the molarity of acetic acid in the vinegar?

Accepted Answer

0.890 M

Question 16

Which of the following best explains why polyprotic acids have successively lower $$K_a$$ values for each proton donated?

Accepted Answer

It becomes increasingly difficult to remove a positively charged proton from a negatively charged anion.

Question 17

Which of the following is true about the pH scale?

Accepted Answer

A change of 1 pH unit corresponds to a tenfold change in $$[\mathrm{H_3O^+}].$$

Question 18

Which of the following best describes the function of a buffer in blood?

Accepted Answer

It prevents drastic changes in pH when small amounts of acid or base are added.

Question 19

A solution has $$[\mathrm{OH^-}] = 2.5 	imes 10$$^{-3}$$\ \mathrm{M}. $$What is the pH of the solution?

Accepted Answer

11.40

Chapter 10: Acids and Bases – Study Notes for GOB Chemistry

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