Question 1

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

Accepted Answer

NaCl

Question 2

A solution of NaF is prepared by dissolving NaF in water. Which equation best represents the reaction that determines the pH of the solution?

Accepted Answer

$$\mathrm{F^- (aq) + H_2O (l) \rightarrow HF (aq) + OH^- (aq)}$$

Question 3

Which of the following cations is considered neutral and does NOT affect the pH of an aqueous solution?

Accepted Answer

$$\mathrm{K^+}$$

Question 4

Which of the following anions will make a solution basic when its sodium salt is dissolved in water?

Accepted Answer

$$\mathrm{CH_3COO^-}$$

Question 5

A 0.1 M solution of NH4Cl is prepared. Which statement best describes the resulting solution?

Accepted Answer

The solution will be acidic because $$\mathrm{NH_4$^+} is $$the conjugate acid of a weak base.

Question 6

Given the following data: $$\mathrm{$$HNO_2$$}$$ $$K_a = 4.5 	imes 10$$^{-4}$$, $$\mathrm{HCN}$$ K_a = 4.9$$ 	imes $$10^{-10}$$, $$\mathrm{$$HONH_2$$}$$ $$K_b = 1.1 	imes 10$$^{-8}$$, $$\mathrm{C_2H_5NH_2}$$ K_b = 6.4$$ 	imes $$10^{-4}$$, rank the following 0.1 M salt solutions in order of increasing pH: $$\mathrm{HONH_3Br}$$, $$\mathrm{$$KNO_3$$}$$, $$\mathrm{C_2H_5NH_3Cl}$$, $$\mathrm{NaCN}.$$

Accepted Answer

$$\mathrm{C_2H_5NH_3Cl} \u003c \mathrm{HONH_3Br} \u003c \mathrm{$$KNO_3$$} \u003c \mathrm{NaCN}$$

Question 7

Which of the following statements is TRUE regarding the pH of a salt solution where both the cation and anion are from weak acids and bases?

Accepted Answer

The solution's pH depends on the relative values of $$K_a$$ and $$K_b$$ for the cation and anion.

Question 8

A 0.55 M solution of lidocaine HCl ($$\mathrm{C$$_{14}$$H_{21}$$NONH_2Cl}$$) is prepared. Given that lidocaine ($$\mathrm{$$C_{14}H$$_{21}$$NONH}) $$has $$pK_b = 7.94$$, what is the first step in calculating the pH of the solution?

Accepted Answer

Calculate $$K_a$$ for the conjugate acid using $$K_a = \dfrac{K_w}{K_b}.$$

Question 9

Which of the following best describes why $$\mathrm{$$NaNO_3$$}$$ produces a neutral solution in water?

Accepted Answer

Both $$\mathrm{Na^+}$$ and $\mathrm{$$NO_3$$^-}$$ are ions of strong acid and strong base, and neither hydrolyzes in water.

Question 10

Which of the following salts would you expect to produce an acidic solution when dissolved in water?

Accepted Answer

$$\mathrm{CH_3NH_3Cl}$$

Question 11

If $$K_b$$ for $$\mathrm{CN^-} is$$ $$1.6 	imes 10$$^{-5}$$ and K_a$ for $$\mathrm{$$NH_4$$^+}$$ is 5.6$$ 	imes $$10^{-10}$$, what is the pH nature of a solution of $$\mathrm{NH_4CN}$$?

Accepted Answer

Basic, because $$K_b \u003e K_a.$$

Question 12

Which of the following is the correct formula to calculate the pH of a basic salt solution after finding $$[OH^-]$$?

Accepted Answer

$$pH = 14.00 - pOH$$

Question 13

Which of the following steps is NOT necessary when determining the pH of a solution of a salt derived from a weak base and a strong acid?

Accepted Answer

Calculate $$K_b$$ for the cation.

Question 14

A student dissolves $$\mathrm{NaCH_3COO} in $$water. Which ion is responsible for the basicity of the solution?

Accepted Answer

$$\mathrm{CH_3COO^-}$$

Question 15

Which of the following is the correct relationship between $$K_a$$, $$K_b$$, and $$K_w$$ for a conjugate acid-base pair?

Accepted Answer

$$K_a 	imes K_b = K_w$$

Question 16

Which of the following best explains why $$\mathrm{$$HSO_4$$^-} is $$considered a weak acid?

Accepted Answer

Because it can donate a proton but does not completely dissociate in water.

Question 17

A solution contains $$\mathrm{C_2H_5NH_3Cl}. $$Which process occurs when the salt dissolves in water?

Accepted Answer

$$\mathrm{C_2H_5NH_3^+}$$ hydrolyzes to produce $$\mathrm{H_3O^+}$$, making the solution acidic.

Question 18

Which of the following is the correct formula to calculate $$K_b$$ from $$pK_b$$?

Accepted Answer

$$K_b = 10$$^{-pK_b}$$

Question 19

Which of the following is the correct sequence of steps to determine the pH of a solution of a salt derived from a weak base and a strong acid?

Accepted Answer

Calculate $$K_a$$ for the conjugate acid, set up an ICE table, solve for $$[H_3O^+]$$, then calculate pH.

pH of Salts Dissolved in Aqueous Solution

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