Question 1

Which property of water allows it to dissolve ionic compounds such as NaCl, but not nonpolar substances like oil?

Accepted Answer

Its polarity and ability to form hydrogen bonds

Question 2

How many hydrogen bonds can a single water molecule form with neighboring water molecules?

Accepted Answer

Four

Question 3

Given the ionization constant of water $$K_w = 1.0 	imes 10$$^{-14}$$ at 25°C, what is the concentration of $$[H^+]$$ in pure water?

Accepted Answer

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

Question 4

If lemon juice has a pH of 2 and beer has a pH of 4, how many times more acidic is lemon juice compared to beer?

Accepted Answer

100 times

Question 5

Which equation correctly relates pH and hydrogen ion concentration?

Accepted Answer

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

Question 6

A buffer solution is made by mixing 0.1 M acetic acid ($$CH_3COOH) $$and 0.6 M acetate ($$CH_3COO^-). If$$ $$pK_a = 4.7$$, what is the pH of the buffer?

Accepted Answer

$$pH = 5.48$$

Question 7

Which statement best describes the role of buffers in biological systems?

Accepted Answer

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

Question 8

Which of the following is true regarding weak acids and their conjugate bases?

Accepted Answer

The conjugate base of a weak acid is also a weak base.

Question 9

What is the $$pK_a of an $$acid if its dissociation constant $$K_a is$$ $$1.8 	imes 10$$^{-5}$$?

Accepted Answer

$$pK_a = 4.74$$

Question 10

Which of the following best explains why changes in pH can affect protein structure and function?

Accepted Answer

pH changes can disrupt ionic and hydrogen bonds within proteins.

Question 11

A solution has $$[OH^-] = 1.0 	imes 10$$^{-10}$$ M. What is its pH?

Accepted Answer

Question 12

Which of the following is the correct Henderson-Hasselbalch equation for a buffer system?

Accepted Answer

$$pH = pK_a + \log \frac{[A^-]}{[HA]}$$

Question 13

If a buffer system has equal concentrations of acid and conjugate base, what is the pH relative to the $$pK_a$$?

Accepted Answer

pH equals $$pK_a$$

Question 14

Which of the following best describes the relationship between $$K_a$$ and $$pK_a$$?

Accepted Answer

$$pK_a = -\log K_a$$

Question 15

A patient’s blood pH drops from 7.4 to 7.0. What is the change in hydrogen ion concentration?

Accepted Answer

Question 16

Which of the following is NOT a property resulting from hydrogen bonding in water?

Accepted Answer

Ability to dissolve nonpolar substances

Question 17

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

Accepted Answer

Each unit decrease in pH represents a tenfold increase in acidity.

Question 18

Which of the following would be the best buffer for a solution with pH near 5?

Accepted Answer

A weak acid with $$pK_a = 5$$

Question 19

If you add a strong base to a buffer system, what happens to the pH?

Accepted Answer

It increases slightly

Question 20

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

Accepted Answer

Carbonic acid-bicarbonate system in blood

Acids, Bases, and Buffer Systems in Biochemistry

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