Biomolecules in water

Question 1

What does pH express?

Answer 1

The acidity/alkalinity of a solution on a logarthmic scale

Question 2

How is pH determined?

Answer 2

Number of free H+ ions in the solution

Question 3

Why is -log10 used in the pH equation?

Answer 3

Concentration values are very small

Question 4

What is the unit for concentration?

Answer 4

Molar (M) , mol/L

Question 5

Why is the pH of water 7?

Answer 5

Because of reversible dissocation of water causing the release of H+ ions

Question 6

What is the equation related to dissocation of water?

Answer 6

𝐻2𝑂 ⇌ 𝐻+ + 𝑂𝐻−

Question 7

What is the equation of water?

Answer 7

[𝐻 +] [𝑂𝐻−] = 1 × 10^−14

Question 8

What are each of the quanities of [H+] and [OH-] when involved with the pH of water?

Answer 8

1x 10^-7

Question 9

What is the pOH?

Answer 9

Concentration of the hydroxide ion

Question 10

What is the equation to find pOH?

Answer 10

− log10 [OH− ]

Question 11

What does pH and pOH add to equal?

Answer 11

14

Question 12

What is Acid dissociation constant?

Answer 12

Strength of an acid determined by its readiness to dissociate in water

Question 13

What is an acid?

Answer 13

Proton donor

Question 14

What is a base?

Answer 14

Proton acceptor

Question 15

What is the equation of pKa?

Answer 15

-log10(Ka)

Question 16

What are buffers comprised of?

Answer 16

Weak acid and conjugate base

Question 17

Purpose of buffers?

Answer 17

Solutions that resist small changes to the pH, maintaining the solution at a constant pH

Question 18

Why is weak acid used in buffers rather than strong acid?

Answer 18

Weak acid partially dissociates, creating a small pH range.

Strong acid fully dissociates, creating a large pH range

Question 19

What is the purpose of tritation curves?

Answer 19

Determine the pKA of a weak acid

Question 20

What is the inflection point?

Answer 20

Where [HA] = [A-] occurs at the middle of the plateau

Question 21

What is a monoprotic acid?

Answer 21

Donates one H+ ion

Question 22

What is a polyprotic acid?

Answer 22

Donates more than one H+ ion

Question 23

What is a strong acid?

Answer 23

Acid that is completely dissociated in watr

Question 24

What is a weak acid?

Answer 24

An acid that partially dissociates in water

Question 25

Why do biological fluids require buffering agnets?

Answer 25

Metabolic reactions create high concentration of organic acid

Question 26

What is the major buffering system in the blood?

Answer 26

Acid-bicarbonate conjuugate pair

Question 27

What is the equation for acid-bicarbonate conjugate pair?

Answer 27

𝐻2𝐶𝑂3 (Carbonic acid) ⇌ 𝐻𝐶𝑂3− (Bicarbonate conjugate base) + 𝐻+

Question 28

Why is carbonic acid a good biological buffer?

Answer 28

Half of acid is carbonic acid and half is conjugate base (becauste pKa is 6.1)

Question 29

What is the buffer region of acid-bicarbonate conjugate base

Answer 29

pH 5.1 - 7.1

Question 30

What happens when H+ levels drop in biological buffer?

Answer 30

Carbonic acid is available to release H+

Question 31

What happens when H+ levels increase in biological buffer?

Answer 31

Conguate base is available to accept H+

Question 32

What happens when blood CO2 increases?

Answer 32

Forward reaction, cause increase in H+ - More frequent and deeper breathing

Question 33

What happens when blood CO2 decreases?

Answer 33

Reverse reaction, less H+ in the blood - Causes hyperventilation

Question 34

What else can be used as a buffer?

Answer 34

Proteins

Question 35

What else can be used as a buffer?

Answer 35

Proteins