Q: Which of the following best explains why the pH of pure water is 7 at 25°C?

Because $$[\mathrm{H^+}] = [\mathrm{OH^-}] = 1.0 \times 10$$^{-7}$$ M

Question 1

According to the Brønsted-Lowry theory, which of the following best describes a base?

Accepted Answer

A substance that accepts a proton ($$\mathrm{H^+})$$

Question 2

Which of the following equations correctly represents the ionic product of water ($$K_w) at 25$$°C?

Accepted Answer

$$K_w = [\mathrm{H^+}][\mathrm{OH^-}]$$

Question 3

A solution has a hydrogen ion concentration of $$1 	imes 10$$^{-5}$$ M. What is its pH?

Accepted Answer

$$5$$

Question 4

Which of the following statements about strong acids is correct?

Accepted Answer

Strong acids completely ionize in water.

Question 5

During an acid-base titration, which of the following best describes the equivalence point?

Accepted Answer

The point where the amount of acid equals the amount of base in moles.

Question 6

Which of the following is the correct formula for calculating pH?

Accepted Answer

$$\mathrm{pH} = -\log_{10}[\mathrm{H^+}]$$

Question 7

A buffer solution is best described as:

Accepted Answer

A solution that maintains a relatively constant pH when small amounts of acid or base are added.

Question 8

If the $$K_w at 25$$°C is $$1.0 	imes 10$$^{-14}$$, what is the concentration of $$\mathrm{OH^-}$$ in pure water?

Accepted Answer

$$1.0 	imes 10$$^{-7}$$ M

Question 9

Which of the following indicators would be most suitable for a titration between a strong acid and a strong base?

Accepted Answer

Phenolphthalein

Question 10

A buffer solution is made by mixing acetic acid and sodium acetate. Which equation best represents the buffer action when a small amount of acid is added?

Accepted Answer

$$\mathrm{CH_3COO^-} + \mathrm{H^+} \rightarrow \mathrm{CH_3COOH}$$

Question 11

Which of the following best explains why the pH of pure water is 7 at 25°C?

Accepted Answer

Because $$[\mathrm{H^+}] = [\mathrm{OH^-}] = 1.0 	imes 10$$^{-7}$$ M

Question 12

Which of the following is a correct statement about the effect of temperature on $$K_w$$?

Accepted Answer

$$K_w$$ increases as temperature increases.

Question 13

A student titrates 25.0 mL of 0.100 M HCl with 0.100 M NaOH. What is the pH at the equivalence point?

Accepted Answer

$$7$$

Question 14

Which of the following best describes the role of a conjugate base in a buffer solution?

Accepted Answer

It reacts with added acid to minimize pH change.

Question 15

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

Accepted Answer

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

Question 16

A weak acid has a $$K_a$$ value of $$1.8 	imes 10$$^{-5}$$. Which of the following statements is true?

Accepted Answer

The acid is stronger than an acid with $$K_a = 1.8 	imes 10$$^{-7}$$.

Question 17

Which of the following best describes the pH curve for the titration of a weak acid with a strong base?

Accepted Answer

The equivalence point occurs at pH greater than 7.

Question 18

Which of the following is a real-life application of buffer solutions?

Accepted Answer

Maintaining blood pH in the human body.

Question 19

A solution has a pH of 3. What is the hydrogen ion concentration?

Accepted Answer

$$1 	imes 10$$^{-3}$$ M

Question 20

Which of the following best explains why indicators change color during a titration?

Accepted Answer

They are weak acids or bases that have different colors in their acid and base forms.

Acid-Base Equilibria: Strong and Weak Acids, pH, and Titrations

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