Question 1

Use the values of Ka in Table 9.5 in the text to identify the stronger acid in each of these pairs: A)HF and HNO₂ B)NH₄⁺ and HCO₃^- C)HCOOH and CH₃COOH

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Question 2

Write the definition of pH.

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Question 3

As the pH value increases, [H₃O⁺] ________.

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Question 4

Indicate whether the following solutions are acidic, basic or neutral. For each concentration calculate the pH of the solution. A)[H⁺] = 1.1 × 10^-3 M B)[H⁺] = 6.0 × 10^-11 M

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Question 5

Calculate the [H₃O⁺] concentrations in solutions with the following pH values: 2.37, 5.65, 8.92, 12.48

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Question 6

Write the definition of pKa.

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Question 7

As pKa increases, the strength of the acid ________.

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Question 8

In a solution that has a pH > pKa, the concentration of the acid form is ________ than that of the conjugate base.

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Question 9

The form of an amino acid where the amine group is protonated and the carboxylic group exists an anion is called a ________.

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Question 10

The isoelectric point occurs when the pH of the solution of the amino acid is ________ between the pKa value for the protonated amine and the pKa value for the carboxylic acid.

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Question 11

A Brønsted and Lowry acid accepts protons.

Accepted Answer

A Brønsted-Lowry acid donates protons, whereas a Brønsted-Lowry base accepts protons.

Question 12

An Arrhenius acid accepts protons.

Accepted Answer

An Arrhenius acid donates protons (H+ ions) in aqueous solution, not accepts them.

Question 13

In the equilibrium HPO₄^2-(aq)+ H₂O(l)? H₂PO₄^-(aq)+ OH^-(aq), H₂O is a Brønsted and Lowry acid.

Accepted Answer

In the given equilibrium, $H_2O$ (water) donates a proton ($H^+$) to another species, which is the behavior of a Brønsted-Lowry acid.

Question 14

The equilibrium constant expression for the reaction, 2 HgO(s)? 2 Hg(l)+ O₂(g)is K = .

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Question 15

An equilibrium with a large value of K favors the reactants.

Accepted Answer

An equilibrium with a large value of K favors the products, indicating that the reaction strongly proceeds towards the formation of products.

Question 16

The strength of an acid increases as Ka increases.

Accepted Answer

The acid dissociation constant (Ka) measures the strength of an acid in solution; a higher Ka value indicates a stronger acid because it signifies a greater extent of dissociation into its ions.

Question 17

When CO₂ is bubbled into water at pH 7, the pH decreases.

Accepted Answer

COS (carbonyl sulfide) when dissolved in water, reacts to form H2CO3 (carbonic acid) and H2S (hydrogen sulfide), both of which can release H+ ions, leading to a decrease in pH.

Question 18

The strength of an acid increases as pKa increases.

Accepted Answer

The strength of an acid decreases as its pKa increases; a lower pKa value indicates a stronger acid.

Question 19

A 1.0 M solution of an acid with a pKa of 5.65 has higher [H₃O⁺] than a 1.0 M solution of an acid with pH of 6.75.

Accepted Answer

A lower pKa value indicates a stronger acid, which dissociates more in solution, resulting in a higher concentration of H₃O⁺ compared to a solution with a higher pH.

Question 20

When the pH of a solution of a weak acid is less than the pKa, the concentration of the acid form is greater than that of the conjugate base.

Accepted Answer

When the pH of a solution is less than the pKa of a weak acid, it means the solution is more acidic, favoring the presence of the acid form (HA) over its conjugate base (A-), thus the concentration of the acid form is greater.

Quiz 9: Acids, Bases, and Buffers in the Body

Use the values of Ka in Table 9.5 in the text to identify the stronger acid in each of these pairs: A)HF and HNO2 B)NH4+ and HCO3- C)HCOOH and CH3COOH