Water and pH: Properties, Significance, and Buffer Systems

Question 1

What is the pH of a solution with a [H+] concentration of 1 x 10^-6 M?

Accepted Answer

6

Answer

7

Answer

8

Answer

9

Question 2

Which of the following is a buffer system?

Accepted Answer

CH3COOH + CH3COONa

Answer

NaOH

Answer

HCl

Answer

H2O

Question 3

What is the primary function of a buffer system in living organisms?

Accepted Answer

To maintain a stable pH

Answer

To provide energy for cellular processes

Answer

To transport substances across cell membranes

Answer

To catalyze biochemical reactions

Question 4

Which of the following is classified as a weak acid?

Accepted Answer

CH3COOH

Answer

HCl

Answer

HNO3

Answer

NaOH

Question 5

Which of the following is a strong base?

Accepted Answer

KOH

Answer

NH3

Answer

CH3COOH

Answer

H2SO3

Question 6

What is the pKa of a weak acid with a Ka of 1 x 10^-4?

Accepted Answer

4

Answer

-4

Answer

10^-4

Answer

-10^-4

Question 7

Water possesses a remarkably high and stable specific heat capacity. Which other property of water contributes to this unique characteristic?

Accepted Answer

High boiling point

Answer

Low density as a solid

Answer

Universal solvent capabilities

Answer

High surface tension

Question 8

Classify the following acid as strong or weak: Carbonic acid (H2CO3)

Accepted Answer

Weak acid

Answer

Strong acid

Question 9

Which of the following best describes the primary function of buffer systems?

Accepted Answer

Maintaining optimal pH levels

Answer

Neutralizing extreme pH changes

Answer

Facilitating chemical reactions

Answer

Transporting ions across cell membranes

Question 10

Identify the conjugate base of the acid H2CO3.

Accepted Answer

HCO3-

Answer

CO32-

Answer

H3O+

Answer

OH-

Question 11

Most biological processes occur optimally within a specific pH range. What is this range?

Accepted Answer

7-9

Answer

3-5

Answer

4-6

Answer

6-8

Question 12

Phosphate buffer systems are widely used in biological applications. Which component is primarily responsible for the buffering action?

Accepted Answer

H2PO4- and HPO42-

Answer

HCO3- and CO32-

Answer

NH3 and NH4+

Answer

CH3COOH and CH3COO-

Question 13

Which of the following accurately describes a buffer solution?

Accepted Answer

Resists changes in pH

Answer

Maintains a pH of 7

Answer

Contains a high concentration of hydroxide ions

Answer

Is highly acidic

Question 14

Bicarbonate ions (HCO3-) play a crucial role in maintaining blood pH by:

Accepted Answer

Accepting protons

Answer

Donating protons

Answer

Neutralizing hydroxide ions

Answer

Converting to carbonic acid

Question 15

Determine the pH of a solution with a hydrogen ion concentration of 1 x 10^-4 M:

Accepted Answer

4

Answer

7

Answer

10

Answer

14

Question 16

Which of the following is classified as a strong acid?

Accepted Answer

Hydrochloric acid (HCl)

Answer

Acetic acid (CH3COOH)

Answer

Carbonic acid (H2CO3)

Answer

Phosphoric acid (H3PO4)

Question 17

Identify the conjugate base of hydrochloric acid (HCl):

Accepted Answer

Cl-

Answer

H2O

Answer

OH-

Answer

H+

Question 18

Which property of water is responsible for its ability to dissolve a vast array of substances?

Accepted Answer

Polarity

Answer

High ionic strength

Answer

Low viscosity

Answer

High dielectric constant

Question 19

Which buffer system is most effective in resisting pH changes when small amounts of acid or base are added?

Accepted Answer

Weak acid and its conjugate base

Answer

Strong acid and its conjugate base

Answer

Strong base and its conjugate acid

Answer

Weak base and its conjugate acid

Question 20

Adding a strong acid to a buffer solution will:

Accepted Answer

Decrease the pH

Answer

Increase the pH

Answer

Not affect the pH

Answer

Increase the buffer capacity

Question 21

Which physiological buffer system plays a crucial role in regulating blood pH?

Accepted Answer

Bicarbonate-carbonic acid

Answer

Phosphate

Answer

Haemoglobin

Answer

Citrate

Question 22

A solution has a pH of 12.0. Which of the following is true?

Accepted Answer

It is basic.

Answer

It is acidic.

Answer

It is neutral.

Answer

It has a [H+] concentration of 10^-12 M.

Question 23

The titration of a weak acid with a strong base typically exhibits:

Accepted Answer

A gradual equivalence point

Answer

A sharp equivalence point

Answer

No equivalence point

Answer

A biphasic equivalence point

Question 24

What is the pH of a solution with a [H+] concentration of 1 x 10^-7 M?

Accepted Answer

7

Answer

0

Answer

14

Answer

10

Question 25

Which of the following is considered a strong acid?

Accepted Answer

Hydrochloric acid

Answer

Acetic acid

Answer

Carbonic acid

Answer

Phosphoric acid

Question 26

Which buffer system primarily regulates pH in the bloodstream?

Accepted Answer

Carbonic acid-bicarbonate

Answer

Phosphate

Answer

Ammonium

Answer

Protein

Question 27

Regarding the pH of pure water:

Accepted Answer

It is neutral

Answer

It is acidic

Answer

It is basic

Answer

It can be either acidic or basic depending on temperature

Question 28

Which of the following accurately describes water?

Accepted Answer

Water forms extensive hydrogen bonds with itself.

Answer

Water is a nonpolar molecule.

Answer

Water has a low dielectric constant.

Answer

Water is a poor conductor of electricity.

Question 29

Calculate the pH of a solution with a hydrogen ion concentration of 1 x 10^-7 M.

Accepted Answer

7

Answer

0

Answer

10

Answer

14

Question 30

Identify the substance that would act as a buffer when added to a solution:

Accepted Answer

Sodium acetate

Answer

Sodium chloride

Answer

Hydrochloric acid

Answer

Glucose

Question 31

What is the primary purpose of the Henderson-Hasselbalch equation?

Accepted Answer

To calculate the pH of a buffer solution accurately.

Answer

To determine the concentration of a weak acid or base precisely.

Answer

To predict the direction of a chemical reaction.

Answer

To measure the electrical conductivity of a solution.

Question 32

Estimate the normal pH range of human blood:

Accepted Answer

7.4

Answer

3.5

Answer

10.0

Answer

12.0

Question 33

Predict the effect of increasing the partial pressure of carbon dioxide on the pH of a solution:

Accepted Answer

Decreases pH

Answer

Increases pH

Answer

No change in pH

Answer

Cannot be determined without knowing the initial pH

Question 34

Which of the following is a defining characteristic of a strong acid?

Accepted Answer

Completely dissociates in water

Answer

Has a high pH

Answer

Is a weak electrolyte

Answer

Reacts slowly with bases

Question 35

Explain the importance of maintaining a stable pH within living organisms.

Accepted Answer

Ensures optimal enzymatic activity

Accepted Answer

Prevents protein denaturation

Accepted Answer

Facilitates ion transport across membranes

Answer

Regulates gene expression

Question 36

Which of the following is the chemical formula of water?

Accepted Answer

H₂O

Answer

CO₂

Answer

H₂SO₄

Answer

NaCl

Question 37

What is the pH range of neutral solutions?

Accepted Answer

6.5 - 7.5

Answer

9.0 - 10.0

Answer

0 - 7

Answer

3.5 - 4.5

Question 38

Which of the following substances is a weak acid?

Accepted Answer

Acetic acid

Answer

Potassium chloride

Answer

Hydrochloric acid

Answer

Sodium hydroxide

Question 39

What is the primary role of buffer systems in maintaining pH balance?

Accepted Answer

Resisting changes in pH by absorbing excess H⁺ or OH⁻ ions

Answer

Lowering the pH of basic solutions

Answer

Producing H⁺ ions in acidic solutions

Question 40

Which of the following is an example of a physiological process that involves pH regulation?

Accepted Answer

Carbon dioxide transport in the blood

Answer

Nerve conduction

Answer

Hormone secretion

Question 41

What is the key difference between a strong acid and a weak acid?

Accepted Answer

Strong acids completely dissociate in water, while weak acids partially dissociate.

Answer

Weak acids are more corrosive than strong acids.

Answer

Strong acids have higher pH values than weak acids.

Question 42

What is the purpose of the Henderson-Hasselbalch equation?

Accepted Answer

Calculating the pH of a buffer solution given the concentrations of the conjugate acid/base pair.

Answer

Predicting the solubility of a compound

Answer

Determining the equilibrium constant of an acid-base reaction

Question 43

Which of the following is a consequence of extreme pH changes in the body?

Accepted Answer

Disruption of enzyme activity and protein structure

Answer

Improved immune function

Answer

Enhanced absorption of nutrients

Question 44

How does the ionization of water contribute to its polarity?

Accepted Answer

It creates a partial positive charge on one end of the molecule and a partial negative charge on the other.

Answer

It increases the solubility of water in organic solvents.