Q: Which of the following statements best describes a Brønsted-Lowry acid?

A substance that donates a proton (H\textsuperscript{+}) to another substance.

Question 1

Which of the following statements best describes a Brønsted-Lowry acid?

Accepted Answer

A substance that donates a proton (H	extsuperscript{+}) to another substance.

Question 2

Which of the following equations correctly represents the dissociation of a weak acid in water?

Accepted Answer

$$\mathrm{CH_3COOH(l) + H_2O(l) \rightleftharpoons CH_3COO^-(aq) + H_3O^+(aq)}$$

Question 3

A solution has a hydronium ion concentration of $$1.0 	imes 10$$^{-4}$$ M. What is its pH?

Accepted Answer

$$4.0$$

Question 4

Which of the following best explains why antacids are effective in treating heartburn?

Accepted Answer

They neutralize excess HCl in the stomach by acting as weak bases.

Question 5

Given the reaction $$\mathrm{$$CaCO_3$$(s) + 2 HCl(aq) ightarrow $$CaCl_2$$(aq) + H_2O(l) + CO_2$(g)}$$, what is the role of CaCO	extsubscript{3} in this reaction?

Accepted Answer

It acts as a weak base, neutralizing the acid.

Question 6

Which of the following statements about the equilibrium constant $$K is $$correct?

Accepted Answer

If $$K = 1$$, products and reactants are present in equal concentrations at equilibrium.

Question 7

A buffer solution is prepared using acetic acid and sodium acetate. Which of the following best describes how this buffer resists changes in pH when a small amount of acid is added?

Accepted Answer

The acetate ion reacts with the added acid to form more acetic acid, minimizing the pH change.

Question 8

If the pKa of acetic acid is 4.76 and the pH of a solution is 3.76, which form is present in greater concentration?

Accepted Answer

The acid form (acetic acid)

Question 9

A patient is experiencing respiratory acidosis due to hypoventilation. Which of the following best explains the chemical change occurring in their blood?

Accepted Answer

CO$$_2$$ builds up, shifting the equilibrium to produce more H$$_3O$^+$$, lowering blood pH.

Question 10

Which of the following is the correct expression for the autoionization constant of water ($$K_w$$)?

Accepted Answer

$$K_w = [H_3O^+][OH^-]$$

Question 11

A solution has a pH of 9. What is the hydronium ion concentration?

Accepted Answer

$$1.0 	imes 10$$^{-9}$$ M

Question 12

Which of the following best describes the effect of increasing the concentration of a reactant on a system at equilibrium, according to Le Châtelier’s Principle?

Accepted Answer

The equilibrium shifts to produce more products.

Question 13

Which of the following is true about strong acids and strong bases in aqueous solution?

Accepted Answer

They dissociate completely, resulting in the formation of salt and water upon neutralization.

Question 14

Which of the following is the correct formula for calculating pH?

Accepted Answer

$$\mathrm{pH = -\log[H_3O^+]}$$

Question 15

A drug has a pKa of 9.42. In which part of the digestive tract will the uncharged form of the drug predominate, making it more likely to be absorbed into the bloodstream?

Accepted Answer

Small intestine (pH 8)

Question 16

Which of the following best explains why local anesthetics must be uncharged to cross nerve-cell membranes?

Accepted Answer

The nerve-cell membrane is nonpolar, so only uncharged (nonpolar) molecules can diffuse across.

Question 17

Which of the following statements about the bicarbonate buffer system in blood is correct?

Accepted Answer

It helps maintain blood pH by reacting with added acids or bases.

Question 18

If a solution has a pH of 6, how does its hydronium ion concentration compare to that of pure water?

Accepted Answer

It is ten times greater than that of pure water.

Question 19

Which of the following is the correct relationship between Ka and pKa?

Accepted Answer

$$\mathrm{pK_a = -\log K_a}$$

Acids, Bases, and Buffers in the Body: Study Guide

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