Question 1

Which of the following best describes why water is considered an amphiprotic substance?

Accepted Answer

Because it can act as both an acid (donating H$$^+) $$and a base (accepting H$$^+) $$depending on the reactant.

Question 2

Given $$[OH^-] = 5.0 	imes 10$$^{-8}$$ M at 25°C, what is the $$[H_3O^+]$$ in the solution? (Use K_w = 1.0$$ 	imes $$10^{-14})$$

Accepted Answer

$$2.0 	imes 10$$^{-7}$$ M

Question 3

A solution has a $$[H_3O^+] of$$ $$1.7 	imes 10$$^{-3}$$ M. What is its pH?

Accepted Answer

2.77

Question 4

Which of the following statements about the pH scale is correct?

Accepted Answer

A solution with pH 2 has one hundred times more $$[H_3O^+]$$ than a solution with pH 4.

Question 5

Which of the following is a correct balanced equation for the neutralization of hydrochloric acid with barium hydroxide?

Accepted Answer

$$2\,HCl\,(aq) + Ba(OH)_2\,(s) \rightarrow 2\,H_2O\,(l) + $$BaCl_2$$\,(aq)$$

Question 6

Which of the following best explains why buffers are important in biological systems?

Accepted Answer

They prevent large fluctuations in pH when small amounts of acid or base are added.

Question 7

If the pH of a solution is 3.42, what is the $$[H_3O^+]$$?

Accepted Answer

$$3.8 	imes 10$$^{-4}$$ M

Question 8

Which of the following household substances is most basic according to the pH scale provided?

Accepted Answer

1 M NaOH solution

Question 9

A buffer solution is prepared using acetic acid and sodium acetate. What happens when a small amount of HCl is added?

Accepted Answer

The added $$H_3O^+ is $$neutralized by the acetate ion, causing only a slight decrease in pH.

Question 10

Which of the following best describes the role of conjugate acid-base pairs in a buffer?

Accepted Answer

They allow the buffer to neutralize added acids or bases without significant pH change.

Question 11

Which equation correctly represents the water dissociation expression ($$K_w$$)?

Accepted Answer

$$K_w = [H_3O^+][OH^-]$$

Question 12

Which of the following is a real-life example of a buffer system in the human body?

Accepted Answer

The bicarbonate/carbonic acid system in blood

Question 13

A student adds a small amount of NaOH to pure water and to a buffer solution, both initially at pH 7. What is the expected outcome?

Accepted Answer

The pH of water increases significantly, while the buffer's pH increases only slightly.

Question 14

Which of the following best describes the effect of adding a strong acid to a buffer solution containing acetic acid and acetate?

Accepted Answer

The added acid is neutralized by the acetate ion, causing only a slight decrease in pH.

Question 15

Which of the following is the correct formula to calculate pH from $$[H_3O^+]$$?

Accepted Answer

$$pH = -\log [H_3O^+]$$

Question 16

Which of the following best explains why indicator papers are useful in measuring pH?

Accepted Answer

They change color based on the pH of the solution, which can be compared to a chart.

Question 17

Which of the following substances is most likely to have a pH closest to 7.0?

Accepted Answer

Pure water

Question 18

Which of the following is true about the relationship between $$[H_3O^+]$$ and $$[OH^-] in a $$neutral solution at 25°C?

Accepted Answer

$$[H_3O^+]$$ equals $$[OH^-]$$

Question 19

Which of the following best describes what happens when a buffer solution is exposed to a small amount of base?

Accepted Answer

The base is neutralized by the weak acid in the buffer, causing only a slight increase in pH.

Water, pH, and Reactions of Acids and Bases

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