Chapter 2.4.3 (Exam 1) Acids and Bases

Question 1

What are acids?

Answer 1

Acids release hydrogen ions (H+) in water

H+ concentration is increased; the solution is acidic

Question 2

What is the effect of too many H+ ions in a solution?

Answer 2

H+ ions can attach to other molecules and change their properties

Question 3

Biological compounds containing a __________ group are acids.

Answer 3

carboxyl

Question 4

What is the difference between weak acids and strong acids?

Answer 4

Weak acids: Not all the acid molecules dissociate into ions (e.g., acetic acid CH₃COOH)

Strong acids, such as hydrochloric acid (HCl), dissociate completely

Question 5

What are bases?

Answer 5

Bases accept H+ ions

Question 6

What is the difference between weak bases and strong bases?

Answer 6

Weak bases: Not all the base molecules dissociate into ions (e.g., HCO₃-)

Strong bases, such as sodium hydroxide (NaOH), dissociate completely

Question 7

How does water act as both a weak acid and a weak base?

Answer 7

Water has a slight tendency to ionize:

H₂O <–> H⁺ + OH^-

The hydroxide anion can accept hydrogen, and the hydrogen cation can be donated

Question 8

Why is water’s tendency to ionize important?

Answer 8

Ionization of water is important because of the abundance of water in living systems and the reactive nature of the H+ ions

Question 9

What is pH?

Answer 9

negative log of the molar concentration of free H+ ions in the solution:

pH = –log[H⁺]

In other words, it’s the measure of hydrogen ion concentration within a solution

Question 10

What is the H⁺ concentration of pure water?

Answer 10

10^-7, or pH = 7

Question 11

How do pH numbers relate with acidity and H⁺ concentration?

Answer 11

Lower pH numbers mean higher H⁺ concentration and greater acidity.

Higher pH numbers mean lower H⁺ concentration and greater alkalinity.

Question 12

Why is pH biologically important?

Answer 12

pH influences rates of biological reactions and can change the 3-D structure of biological molecules, which impacts function

Organisms use many mechanisms to minimize change in pH in their cells and tissues

Question 13

What is one way living organisms are able to maintain a constant internal pH for homeostasis?

Answer 13

Buffers help maintain constant pH

Question 14

What is a buffer?

Answer 14

a weak acid and its corresponding base, e.g.,
carbonic acid (H₂CO₃), and
bicarbonate ion (HCO₃^-)
HCO₃^- + H⁺ <–> H₂CO₃