Q: Which of the following is the correct formula for percent ionization?

$$\text{Percent Ionization} = \frac{[H_3O^+]_{\text{equil}}}{[HA]_{\text{init}}} \times 100\%$$

Question 1

Which of the following salts will produce an acidic solution when dissolved in water?

Accepted Answer

NH4Cl

Question 2

A 0.080 M solution of sodium cyanide (NaCN) is prepared. Given that the acid-dissociation constant of hydrocyanic acid (HCN) at 25.0°C is $$K_a = 4.9 	imes 10$$^{-10}$$, what is the pH of the solution?

Accepted Answer

11.11

Question 3

What is the concentration of ammonia ($$NH_3) in an $$aqueous solution with a pH of 11.00? ($$K_b = 1.8 	imes 10$$^{-5}$$)

Accepted Answer

0.056\,	ext{M}

Question 4

Calculate the pH of a 0.100 M $$NH_3$$ solution. ($$K_b = 1.8 	imes 10$$^{-5}$$)

Accepted Answer

11.13

Question 5

What is the pOH of a nitrous acid solution that contains $$3.9 	imes 10$$^{-8}$$\,	ext{M}\,H_3O^+ at 25$$°C?

Accepted Answer

8.41

Question 6

Which of the following acids is the strongest?

Accepted Answer

HBrO4

Question 7

Which equation correctly relates the acid dissociation constant ($$K_a) to $$its $$pK_a$$?

Accepted Answer

$$pK_a = -\log(K_a)$$

Question 8

A weak acid solution has an initial concentration of $$0.10\,	ext{M}$$ and an equilibrium $$[H_3O^+] of$$ $$1.0 	imes 10$$^{-3}$$\,	ext{M}. $$What is the percent ionization?

Accepted Answer

$$10\%$$

Question 9

Which of the following statements best explains why $$NH_4Cl$$ forms an acidic solution in water?

Accepted Answer

The $$NH_4$$^+$$ ion acts as a weak acid and donates a proton to water.

Question 10

If the $$K_b of a $$base is $$1.8 	imes 10$$^{-5}$$, what is its pK_b$?

Accepted Answer

$$pK_b = 4.74$$

Question 11

A solution has a $$[H_3O^+] of$$ $$1.0 	imes 10$$^{-6}$$\,	ext{M}. $$What is the pH?

Accepted Answer

6.0

Question 12

Which of the following ions will NOT hydrolyze in water?

Accepted Answer

$$Na^+$$

Question 13

A buffer solution is made by mixing equal concentrations of $$NH_3$$ and $$NH_4Cl. $$What will happen to the pH if a small amount of $$HCl is $$added?

Accepted Answer

The pH will decrease slightly, but the buffer will resist large changes.

Question 14

Which of the following is the correct formula for percent ionization?

Accepted Answer

$$	ext{Percent Ionization} = \frac{[H_3O^+]_{	ext{equil}}}{[HA]_{	ext{init}}} 	imes 100\%$$

Question 15

Which of the following would increase the percent ionization of a weak acid?

Accepted Answer

Diluting the solution

Question 16

A student mixes $$0.10\,	ext{M}$$ $$NH_3$$ with $$0.10\,	ext{M}$$ $$NH_4Cl. $$What is the primary purpose of this mixture?

Accepted Answer

To create a buffer solution

Question 17

Which of the following statements about $$HBrO_4 is $$correct?

Accepted Answer

It is a stronger acid than $$HBrO_3$$ because it has more oxygen atoms.

Question 18

If a solution has a pOH of 8.41, what is its pH at 25°C?

Accepted Answer

5.59

Question 19

Which of the following is a correct relationship between $$pK_a$$ and $$K_a$$?

Accepted Answer

$$pK_a = -\log(K_a)$$

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