$$[H^+] = 1 \times 10^{-2}\ \mathrm{M}$$

$$K_w = [H^+][OH^-] = 1 \times 10^{-14}$$

Question 1

Which property of water is primarily responsible for its ability to dissolve ionic compounds like 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

Which equation correctly represents the ionization of water?

Accepted Answer

$$2\ \mathrm{H_2O} \rightleftharpoons \mathrm{H_3O^+} + \mathrm{OH^-}$$

Question 4

Given that the ion product of water is $$K_w = [H^+][OH^-] = 1 	imes 10$$^{-14}$$ at 25°C, what is the pH of pure water?

Accepted Answer

$$pH = 7$$

Question 5

A solution has a pH of 2. What is the concentration of hydronium ions $$[H^+] in $$this solution?

Accepted Answer

$$[H^+] = 1 	imes 10^{-2}\ \mathrm{M}$$

Question 6

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 7

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

Accepted Answer

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

Question 8

Which equation is used to calculate the pH of a buffer solution containing a weak acid and its conjugate base?

Accepted Answer

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

Question 9

Calculate the pH of a buffer solution made with 0.1 M acetic acid and 0.6 M acetate, given $$K_a = 1.8 	imes 10$$^{-5}$$. (pK_a = 4.7$)

Accepted Answer

$$pH = 5.48$$

Question 10

Which of the following statements about the relationship between pH and pKa is correct?

Accepted Answer

When $$pH = pK_a$$, the concentrations of acid and conjugate base are equal

Question 11

A patient with severe diabetes is found to have a blood pH of 7.1. What is the clinical term for this condition?

Accepted Answer

Acidosis

Question 12

Which of the following best explains why ice floats on liquid water?

Accepted Answer

Ice is less dense due to the stable hydrogen-bonded lattice structure

Question 13

Which of the following molecules is amphipathic and can form micelles in water?

Accepted Answer

Phospholipids

Question 14

Which of the following is true about the $$K_w ($$ion product) of water at 25°C?

Accepted Answer

$$K_w = [H^+][OH^-] = 1 	imes 10^{-14}$$

Question 15

Which of the following best describes the role of histidine in proteins near physiological pH?

Accepted Answer

It acts as a buffer, facilitating enzymatic reactions by donating or accepting protons

Question 16

Which of the following is the correct expression for the acid dissociation constant ($$K_a) $$for acetic acid?

Accepted Answer

$$K_a = \frac{[CH_3COO^-][H^+]}{[CH_3COOH]}$$

Question 17

A buffer is most effective when:

Accepted Answer

The concentrations of acid and conjugate base are equal

Question 18

Which of the following best explains why the pH scale is logarithmic rather than linear?

Accepted Answer

It allows for easier comparison of relative changes in $$[H^+]$$ over a wide range

Question 19

Which of the following is a real-life application of the Henderson-Hasselbalch equation in medicine?

Accepted Answer

Calculating blood pH changes in metabolic acidosis

Water, Acids, Bases, and Buffers in Biochemistry

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