Which of the following is a Brønsted-Lowry base, but not an Arrhenius base? (LO 16.1) (a) HNO3 (b) CsOH (c) CH3NH2 (d) CH3OH

Verified step by step guidance

1. Understand the definitions: A Brønsted-Lowry base is a substance that can accept a proton (H+), while an Arrhenius base is a substance that increases the concentration of hydroxide ions (OH-) in aqueous solution.
2. Analyze each option: (a) HNO3 is a strong acid, not a base. (b) CsOH is an Arrhenius base because it dissociates in water to produce OH- ions.
3. Consider option (c) CH3NH2: Methylamine (CH3NH2) can accept a proton to form CH3NH3+, making it a Brønsted-Lowry base. It does not produce OH- ions directly in solution, so it is not an Arrhenius base.
4. Evaluate option (d) CH3OH: Methanol (CH3OH) is neither a Brønsted-Lowry base nor an Arrhenius base as it does not accept protons or produce OH- ions in solution.
5. Conclude that the correct answer is (c) CH3NH2, as it is a Brønsted-Lowry base but not an Arrhenius base.

Key Concepts

Brønsted-Lowry Theory

The Brønsted-Lowry theory defines acids as proton (H+) donors and bases as proton acceptors. This theory broadens the definition of bases beyond those that simply produce hydroxide ions in solution, allowing for a wider range of substances to be classified as bases based on their ability to accept protons.

Arrhenius Theory

The Arrhenius theory classifies acids as substances that increase the concentration of hydrogen ions (H+) in aqueous solution and bases as substances that increase the concentration of hydroxide ions (OH-). This definition is more restrictive, as it only considers substances that dissociate in water to produce these ions, limiting the classification of bases.

Comparative Analysis of Bases

To determine which substance is a Brønsted-Lowry base but not an Arrhenius base, one must analyze the ability of each option to accept protons without necessarily producing hydroxide ions in solution. This involves understanding the chemical structure and behavior of the compounds listed, particularly focusing on their ability to act as proton acceptors.