Which of the following is a Brønsted-Lowry base? This question often appears in chemistry exams and is crucial for understanding acid-base reactions. In this article, we will explore the concept of Brønsted-Lowry bases, their characteristics, and how to identify them among various substances.
A Brønsted-Lowry base is defined as a substance that can accept a proton (H⁺) from another substance. This definition is different from the Arrhenius theory, which defines a base as a substance that produces hydroxide ions (OH⁻) in an aqueous solution. The Brønsted-Lowry theory is more general and can be applied to both aqueous and non-aqueous solutions.
To identify a Brønsted-Lowry base, we need to look for the following characteristics:
1. Presence of a lone pair of electrons: A Brønsted-Lowry base must have a lone pair of electrons available to accept a proton. This is because the lone pair will form a new bond with the proton, resulting in the formation of a new compound.
2. Electron-donating groups: Substances with electron-donating groups, such as alkyl groups or lone pairs of electrons on nitrogen or oxygen atoms, are more likely to act as Brønsted-Lowry bases. These groups help stabilize the negative charge that forms when the base accepts a proton.
3. Solubility in water: While not a strict requirement, many Brønsted-Lowry bases are soluble in water. This is because water can solvate the base and facilitate the proton transfer.
Now, let’s analyze some examples to determine which of the following is a Brønsted-Lowry base:
A) HCl
B) NaOH
C) NH₃
D) H₂O
A) HCl is a Brønsted-Lowry acid, as it can donate a proton. B) NaOH is a Brønsted-Lowry base because it can donate hydroxide ions (OH⁻) in an aqueous solution. C) NH₃ is a Brønsted-Lowry base because it has a lone pair of electrons on the nitrogen atom, allowing it to accept a proton. D) H₂O can act as both a Brønsted-Lowry acid and a base, as it can donate a proton (acting as an acid) or accept a proton (acting as a base).
Therefore, the correct answer to the question “Which of the following is a Brønsted-Lowry base?” is C) NH₃. This example demonstrates the importance of understanding the Brønsted-Lowry theory to identify bases and predict acid-base reactions.
