Indicate whether each of the following statements is correct...

Indicate whether each of the following statements is correct or incorrect. (a) Every Brønsted-Lowry acid is also a Lewis acid. (b) Every Lewis acid is also a Bronsted-Lowry acid. (c) Conjugate acids of weak bases produce more acidic solutions than conjugate acids of strong bases. (d) $\mathrm{K}^{+}$ ion is acidic in water because it causes hydrating water molecules to become more acidic. (e) The percent ionization of a weak acid in water increases as the concentration of acid decreases.

Indicate whether each of the following statements is correct or incorrect.
(a) Every Brønsted-Lowry acid is also a Lewis acid.
(b) Every Lewis acid is also a Bronsted-Lowry acid.
(c) Conjugate acids of weak bases produce more acidic solutions than conjugate acids of strong bases.
(d) $\mathrm{K}^{+}$ ion is acidic in water because it causes hydrating water molecules to become more acidic.
(e) The percent ionization of a weak acid in water increases as the concentration of acid decreases.

Key Concepts

Dilution Effect on Weak Acid Ionization

The percent ionization of a weak acid in water tends to increase as the acid concentration decreases. This is due to Le Chatelier’s principle, where the equilibrium shifts to produce more ions when the concentration is lower, despite the overall low ionization constant. This concept explains how changing the concentration of reactants in a weak acid equilibrium will affect the degree of ionization and the resultant pH.

Cation Hydrolysis in Aqueous Solutions

Cation hydrolysis involves the interaction of metal ions with water molecules, potentially producing acidic or basic solutions through the polarization of water. However, in many cases, such as with alkali metal cations like K+, the effect is minimal due to their low charge density and weak ability to polarize water. Understanding this helps in distinguishing between ions that actively participate in acid-base chemistry and those that act as spectators.

Conjugate Acid/Base Relationships

This concept deals with the relationship between a base and its conjugate acid formed after the base accepts a proton. The relative strength of a conjugate acid is inversely related to the strength of its parent base; weak bases produce conjugate acids that are relatively stronger (more acidic) compared to those formed from strong bases. This is fundamental in predicting the pH of solutions formed by the reaction of bases with water.

Comparison of Acid-Base Theories

Comparing the Bronsted-Lowry and Lewis definitions highlights that while every Bronsted-Lowry acid (a proton donor) can accept an electron pair (thus functioning as a Lewis acid), not every Lewis acid donates a proton. This distinction is crucial for understanding reactions that do or do not involve proton transfer, emphasizing the specific conditions under which each theory applies.

Bronsted-Lowry Acid

This concept refers to substances that donate protons (H+ ions) in chemical reactions. It provides a framework for understanding acid-base reactions by focusing on proton transfer rather than electron pairs, which is particularly useful for reactions in aqueous solutions.

Lewis Acid

A Lewis acid is defined as a substance capable of accepting an electron pair. This theory broadens the definition of acids and bases beyond proton transfer, including reactions where electron acceptors interact with electron donors, providing a more general view applicable to a wider range of chemical reactions.

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