16.1.1 Arrhenius/Brønsted-Lowry Definitions of Acids and Bases

Question 1

Arrhenius/Brønsted-Lowry Definitions of Acids and Bases

Answer 1

• Brønsted-Lowry acids donate protons in solution, while Brønsted-Lowry bases accept protons in solution.
• A strong acid or strong base completely dissociates in aqueous solution, whereas weak acids and weak bases only partially dissociate in aqueous solution.
• Acid strength is not related to concentration.

Question 2

note

Answer 2

• Brønsted-Lowry acids donate protons in solution, while
  Brønsted-Lowry bases accept protons in solution.
• In the example of an acid, nitric acid (HNO 3 ) donates a proton to water (H 2 O) creating a nitrate ion (NO 3– ) and a hydronium ion (H 3 O + ). The nitrate ion itself is a Brønsted-Lowry base and the hydronium ion is a Brønsted-Lowry acid.
• In the example of a base, ammonia (NH 3 ) accepts a proton from water, creating an ammonium ion (NH 4+ ) and a hydroxide ion (OH – ). The ammonium ion itself is a Brønsted-Lowry acid, and the hydroxide ion is a
  Brønsted-Lowry base.
• Ammonia and ammonium ion form a conjugate acid-base pair as do water and hydroxide ion. Likewise, nitric acid is the conjugate acid of the nitrate ion, and water is the conjugate base of the hydronium ion.
• A strong acid or strong base completely dissociates in aqueous solution, whereas weak acids and weak bases only partially dissociate in aqueous solution.
• The chart ranks acids from strong to weak and their associated conjugate bases from weak to strong. The conjugate base of a strong acid is very weak, and the conjugate acid of a strong base is very weak.
• Acid strength is not related to concentration. A strong acid is not necessarily highly concentrated. The example shows a hydrochloric acid (HCl, a strong acid) solution that is very dilute and a hydrofluoric acid (HF, a weak acid) that is very concentrated.

Question 3

Which is not an important difference between the Arrhenius concept and the Brønsted-Lowry concept of acids and bases?

Answer 3

The Brønsted-Lowry concept relies on the hydroxide ion as its base.

Question 4

Examine the pH scale below. How does stomach acid compare to pure water?

Answer 4

Stomach acid is one hundred thousand times as acidic as pure water.

Question 5

Which of the following statements is false?

Answer 5

The conjugate base of a strong acid is a much stronger base than water.

Question 6

Which of the following conjugate acid / base pairs is incorrect?

Answer 6

H2SO4 / SO42−

Question 7

Which of the following conjugate acid / base pairs is incorrect?

Answer 7

H + / OH −

Question 8

What is the name given to a substance that can behave either as an acid or as a base?

Answer 8

amphoteric

Question 9

Which of the following statements best summarizes the Brønsted-Lowry concept of acids and bases?

Answer 9

The Brønsted-Lowry concept defines acids and bases in terms of their ability to donate or accept protons.

Question 10

All of the following are polyprotic acids except:

Answer 10

HCl

Question 11

Which of the following can be considered a concentrated solution of a weak acid?

Answer 11

1 M HF

Question 12

All of the following are considered binary strong acids except:

Answer 12

Chloric acid