Q: A solution has $$[\mathrm{H_3O^+}] = 2.0 \times 10$$^{-5}$$\ \mathrm{M}. $$What is the pH of this solution?

$$\mathrm{pH} = -\log(2.0 \times 10$$^{-5}$$) = 4.70$$

Q: What is the $$[\mathrm{OH^-}] in a $$solution at 25°C where $$[\mathrm{H_3O^+}] = 1.0 \times 10$$^{-9}$$\ \mathrm{M}$$?

$$[\mathrm{OH^-}] = \dfrac{1.0 \times 10$$^{-14}$$}{1.0 \times 10$$^{-9}$$} = 1.0 \times 10$$^{-5}$$\ \mathrm{M}$$

Question 1

Which of the following statements best explains why hydrochloric acid (HCl) is considered a strong acid in aqueous solution?

Accepted Answer

HCl completely ionizes in water, producing $$\mathrm{H_3O^+}$$ and $$\mathrm{Cl^-}$$ ions.

Question 2

A student adds sodium hydroxide (NaOH) to a solution of hydrochloric acid (HCl) during a titration. What is the net ionic equation for the neutralization reaction that occurs?

Accepted Answer

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

Question 3

Which property is NOT characteristic of acids?

Accepted Answer

They turn blue litmus paper red.

Question 4

Which of the following substances is amphoteric, meaning it can act as either an acid or a base?

Accepted Answer

Water ($$\mathrm{H_2O})$$

Question 5

A solution has $$[\mathrm{H_3O^+}] = 2.0 	imes 10$$^{-5}$$\ \mathrm{M}. $$What is the pH of this solution?

Accepted Answer

$$\mathrm{pH} = -\log(2.0 	imes 10$$^{-5}$$) = 4.70$$

Question 6

Which of the following is a weak acid?

Accepted Answer

Acetic acid ($$\mathrm{HC_2H_3O_2})$$

Question 7

Which of the following best describes a buffer solution?

Accepted Answer

A solution that contains significant amounts of both a weak acid and its conjugate base.

Question 8

What is the $$[\mathrm{OH^-}] in a $$solution at 25°C where $$[\mathrm{H_3O^+}] = 1.0 	imes 10$$^{-9}$$\ \mathrm{M}$$?

Accepted Answer

$$[\mathrm{OH^-}] = \dfrac{1.0 	imes 10$$^{-14}$$}{1.0 	imes 10$$^{-9}$$} = 1.0 	imes 10$$^{-5}$$\ \mathrm{M}$$

Question 9

Which of the following reactions is an example of a gas evolution reaction involving an acid and a carbonate?

Accepted Answer

$$\mathrm{HCl(aq) + $$NaHCO_3$$(aq) \rightarrow H_2O(l) + CO_2$(g) + NaCl(aq)}$$

Question 10

Which of the following is a strong base?

Accepted Answer

Potassium hydroxide ($$\mathrm{KOH})$$

Question 11

A solution is found to turn red litmus paper blue and feels slippery to the touch. Which of the following is most likely present in the solution?

Accepted Answer

A base such as sodium hydroxide ($$\mathrm{NaOH})$$

Question 12

Which of the following best describes the Brønsted–Lowry definition of a base?

Accepted Answer

A base is a proton acceptor.

Question 13

Which of the following pairs is a conjugate acid–base pair?

Accepted Answer

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

Question 14

A 0.025 M solution of $$\mathrm{Sr(OH)_2} is $$prepared. What is the concentration of $$\mathrm{OH^-}$$ ions in the solution?

Accepted Answer

$$[\mathrm{OH^-}] = 2 	imes 0.025\ \mathrm{M} = 0.050\ \mathrm{M}$$

Question 15

Which of the following best explains why strong acids conduct electricity better than weak acids?

Accepted Answer

Strong acids completely ionize in solution, producing more ions to carry electric current.

Question 16

A buffer solution is made by mixing acetic acid and sodium acetate. What happens when a small amount of hydrochloric acid is added to this buffer?

Accepted Answer

The acetate ion reacts with the added acid, minimizing the change in pH.

Question 17

Which of the following is the correct formula for the ion product constant for water at 25°C?

Accepted Answer

$$[\mathrm{H_3O^+}][\mathrm{OH^-}] = 1.0 	imes 10$$^{-14}$$

Question 18

A titration requires 12.54 mL of 0.100 M NaOH to neutralize 10.00 mL of HCl. What is the concentration of the HCl solution?

Accepted Answer

$$\mathrm{M_{HCl}} = \dfrac{(12.54\ \mathrm{mL}) 	imes (0.100\ \mathrm{mol/L})}{1000\ \mathrm{mL/L}} \div 0.01000\ \mathrm{L} = 0.125\ \mathrm{M}$$

Question 19

Which of the following is a real-world consequence of acid rain?

Accepted Answer

Acid rain dissolves metals and metal oxides, damaging buildings and statues.

Acids and Bases: Properties, Definitions, and Reactions

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