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

Question 1

Which of the following best describes a buffer in a biological system?

Accepted Answer

A solution that resists changes in pH when small amounts of acid or base are added.

Question 2

If the concentration of hydrogen ions $$[H^+] in a $$solution is $$1 	imes 10$$^{-5}$$ M, what is the pH of the solution?

Accepted Answer

$$pH = 5$$

Question 3

Which of the following statements about strong acids is correct?

Accepted Answer

Strong acids completely dissociate in water, releasing all their $$H^+$$ ions.

Question 4

A solution has a pH of 3. What is the $$[H^+]$$ concentration?

Accepted Answer

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

Question 5

Which of the following is true about the relationship between $$[H^+]$$ and $$[OH^-] in $$pure water at 25°C?

Accepted Answer

$$[H^+] = [OH^-]$$

Question 6

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 7

Which of the following is a correct definition of a base according to the Bronsted-Lowry theory?

Accepted Answer

A substance that accepts a proton ($$H^+).$$

Question 8

Which of the following best explains why blood pH must be tightly regulated in humans?

Accepted Answer

Enzyme activity and metabolic processes are highly sensitive to pH changes.

Question 9

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

Accepted Answer

The pH decreases only slightly because the buffer neutralizes the added acid.

Question 10

Which of the following equations correctly relates pH and $$[H^+]$$?

Accepted Answer

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

Question 11

Which of the following is a physiological buffer system in human blood?

Accepted Answer

Bicarbonate buffer system ($$H_2CO_3 / $$HCO_3$$^-)$$

Question 12

Which of the following best describes a strong base?

Accepted Answer

A substance that completely dissociates in water to release $$OH^-$$ ions.

Question 13

If a solution has $$[OH^-] = 1 	imes 10$$^{-2}$$ M, what is the pOH?

Accepted Answer

$$pOH = 2$$

Question 14

Which of the following is true about the pH scale?

Accepted Answer

Each unit change represents a tenfold change in $$[H^+]$$ concentration.

Question 15

Which of the following would NOT affect the pH of a solution?

Accepted Answer

Adding sodium chloride (NaCl)

Question 16

A solution has a pOH of 4. What is the pH at 25°C?

Accepted Answer

$$pH = 10$$

Question 17

Which of the following is a property of weak acids?

Accepted Answer

They partially dissociate in water.

Question 18

Which of the following best describes the effect of a buffer when a small amount of base is added to a buffered solution?

Accepted Answer

The buffer neutralizes the base, minimizing the increase in pH.

Question 19

Which of the following is the correct formula for calculating $$[OH^-]$$ from pOH?

Accepted Answer

$$[OH^-] = 10$$^{-pOH}$$

Question 20

Which of the following is the best example of a real-life buffer system?

Accepted Answer

The bicarbonate buffer system in human blood.

Acids, Bases, pH, and Buffers in Biological Systems

Study Guide - Practice Questions