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

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

Q: Calculate the $$[\mathrm{H_3O^+}] in a $$solution with a pH of 7.4.

$$4.0 \times 10$$^{-8}$$\ \mathrm{M}$$

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 diprotic?

Accepted Answer

$$\mathrm{H_2SO_4}$$

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 strong and weak acids 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 $$[\mathrm{H_3O^+}] in a $$solution with a pH of 7.4.

Accepted Answer

$$4.0 	imes 10$$^{-8}$$\ \mathrm{M}$$

Question 10

A 0.0032 M NaOH solution has a pH closest to:

Accepted Answer

11.5

Question 11

Which of the following best explains why the $$K_a$$ value for the second dissociation of a polyprotic acid is much lower than the first?

Accepted Answer

It is more difficult to remove a proton from a negatively charged anion.

Question 12

A buffer is prepared by mixing 0.100 M acetic acid ($$\mathrm{CH_3COOH}$$, $$K_a = 1.8 	imes 10$$^{-5}$$) and 0.100 M sodium acetate ($$\mathrm{CH_3COONa}$$). What is the pH of the buffer? (Use $$\mathrm{p}K_a = 4.74$$)

Accepted Answer

4.74

Question 13

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 14

If 6.5 g of $$\mathrm{H_2SO_4} ($$molar mass = 98.0 g/mol) is dissolved to make 200 mL of solution, what is the normality of the solution?

Accepted Answer

0.66 N

Question 15

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 16

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

0.89 M

Question 17

Which of the following is true about the relationship between acid and conjugate base strength?

Accepted Answer

The stronger the acid, the weaker its conjugate base.

Question 18

Which of the following best explains why antacids containing carbonate are effective in neutralizing excess stomach acid?

Accepted Answer

Carbonate ions react with $$\mathrm{H^+} to $$form $$\mathrm{CO_2$}$$ and water.

Question 19

Which of the following is the correct Henderson-Hasselbalch equation for a buffer solution containing a weak acid (HA) and its conjugate base (A$$^-$$)?

Accepted Answer

$$\mathrm{pH} = \mathrm{p}K_a + \log \left( \dfrac{[\mathrm{A}^-]}{[\mathrm{HA}]} \right)$$

Acids and Bases: Definitions, Properties, and Reactions

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