A Buffer May Be Prepared by Mixing a Weak Acid

question 11

Multiple Choice

A buffer may be prepared by mixing a weak acid with a roughly equivalent amount of strong base.Which of the acids below is best for the preparation of a buffer with a pH of 4.00?

• A) sulfurous acid ,H₂SO₃;K_a = 1.7 × 10−²
• B) hydrofluoric acid,HF;K_a = 6.9 × 10−⁴
• C) benzoic acid,HC₇H₅O₂;K_a = 6.6 × 10−⁵
• D) dihydrogen phosphate ion,H₂PO₄−;K_a = 6.2 × 10−⁸
• E) ammonium ion,NH₄⁺;K_a = 5.6 × 10−¹⁰

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Definitions:

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A condition in which cells reduce their responsiveness to a substance after repeated exposure.

Physostigmine

A reversible cholinesterase inhibitor used to treat glaucoma and to counteract the effects of neuromuscular blocking in anesthesia.

Acetylcholine

Acetylcholine is a neurotransmitter involved in many functions including muscle stimulation, memory, and alertness, playing a significant role in the autonomic nervous system.

Slowing

The process of reducing speed or rate, often used in contexts such as cognitive slowing with aging.