Q: If the concentration of $$[OH^-] in a $$solution is $$1 \times 10$$^{-9}$$ M at 25°C, what is the $$[H^+]$$?

$$[H^+] = 1 \times 10$$^{-5}$$ M

Q: Which of the following is the correct relationship for the ion product of water at 25°C?

$$[H^+][OH^-] = 1 \times 10$$^{-14}$$

Question 1

Which of the following best describes the autoionization of water at 25°C?

Accepted Answer

$$2H_2O \rightleftharpoons H_3O^+ + OH^-$$

Question 2

A solution has $$[H^+] = 1 	imes 10$$^{-4}$$ M. What is its pH?

Accepted Answer

$$pH = 4$$

Question 3

Which of the following statements about strong acids is correct?

Accepted Answer

Strong acids completely ionize in water.

Question 4

If the concentration of $$[OH^-] in a $$solution is $$1 	imes 10$$^{-9}$$ M at 25°C, what is the $$[H^+]$$?

Accepted Answer

$$[H^+] = 1 	imes 10$$^{-5}$$ M

Question 5

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

Accepted Answer

Buffers resist changes in pH when small amounts of acid or base are added.

Question 6

The carbonic acid-bicarbonate buffer system in blood involves which of the following equilibrium reactions?

Accepted Answer

$$CO_2 + H_2O$$ \rightleftharpoons H_2CO_3 \rightleftharpoons $$HCO_3^- + H$$^+$$

Question 7

A patient’s blood pH drops to 7.1. Which of the following best describes what happens in the carbonic acid-bicarbonate buffer system?

Accepted Answer

Bicarbonate ions ($$HCO_3$$^-$$) combine with excess H$$^+$$ to form carbonic acid (H_2CO_3$).

Question 8

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

Accepted Answer

$$[H^+][OH^-] = 1 	imes 10$$^{-14}$$

Question 9

Which of the following best describes a conjugate acid-base pair?

Accepted Answer

Two species that differ by one proton ($$H^+).$$

Question 10

A solution has a pH of 9. Which of the following best describes this solution?

Accepted Answer

It is basic, with $$[OH^-] \u003e [H^+].$$

Question 11

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

Accepted Answer

The carbonic acid-bicarbonate system in blood.

Question 12

If a solution has a pH of 3, what is the $$[H^+]$$ concentration?

Accepted Answer

$$[H^+] = 1 	imes 10$$^{-3}$$ M

Question 13

Which of the following best explains why maintaining a stable pH is critical for cellular function?

Accepted Answer

Changes in pH can alter the shape and function of biological molecules.

Question 14

Which of the following is the correct net ionic equation for the neutralization of hydrochloric acid with sodium hydroxide?

Accepted Answer

$$H^+ + OH^- \rightarrow H_2O$$

Question 15

A buffer is made by mixing acetic acid ($$CH_3COOH) $$and sodium acetate ($$CH_3COONa). $$Which of the following best describes how this buffer resists changes in pH when a small amount of acid is added?

Accepted Answer

The acetate ion ($$CH_3COO^-) $$reacts with the added $$H^+ to $$form acetic acid.

Question 16

If the pH of a solution changes from 6 to 4, how does the $$[H^+]$$ concentration change?

Accepted Answer

It increases by 100 times.

Question 17

Which of the following is true about weak acids?

Accepted Answer

They partially ionize in water.

Question 18

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

Accepted Answer

It combines with excess $$H^+$$ ions to minimize pH changes.

Question 19

A solution contains $$[H^+] = 1 	imes 10$$^{-8}$$ M. What is the $$[OH^-]$$ at 25°C?

Accepted Answer

$$[OH^-] = 1 	imes 10$$^{-6}$$ M

Question 20

Which of the following best describes the effect of adding a strong base to a buffered solution?

Accepted Answer

The buffer will react with the added base to minimize the increase in pH.

Acids, Bases, pH, and Buffers: Foundations for Organic and Biological Chemistry

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