Question

Below are three organic acids that can all react as acids. Name the molecules and explain how you expect their acid character. Justify in detail why in your reasoning.

Answer 1

Organic acids such as acetic acid are characterized by their carboxyl group, which enables them to act as acids by donating a proton to bases. The strength of an organic acid is determined by the stability of the resulting carboxylate anion, influenced by factors like resonance and electronegative substituents.

Step-by-step explanation:

Organic acids, such as acetic acid, contain a carboxyl group, which is responsible for their acidic character. This group consists of a carbon atom double-bonded to an oxygen atom (carbonyl) and single-bonded to a hydroxyl group. The acid strength of a carboxylic acid depends on the stability of the carboxylate anion formed when the acid donates its proton (hydrogen ion) to a base, such as water. Factors influencing this stability and therefore the acid strength include the presence of electron-withdrawing substituents that stabilize the anion through resonance and inductive effects.

For example, in the reaction of a carboxylic acid with water, the carboxylic acid dissociates by donating its proton to water, forming the hydronium ion and the carboxylate anion. When comparing different organic acids, it's crucial to analyze their structures to predict their relative acidity. Ascorbic acid (vitamin C), for instance, is more acidic than acetic acid due to the additional electronegative groups it contains, which contribute to a more stabilized anion. Acid-base reactions are fundamental in organic chemistry, illustrating the interchange of protons between molecules.

Answer 2

The three organic acids are Acetic acid (CH₃COOH), Formic acid (HCOOH), and Citric acid (C₆H₈O₇). Their acid character is attributed to the presence of hydrogen ions (H⁺) that dissociate in solution, contributing to their acidic properties. Acidity is influenced by the stability of the resulting conjugate base after the release of the hydrogen ion.

Step-by-step explanation:

Acetic acid (CH₃COOH) is a weak organic acid that dissociates partially in water, releasing hydrogen ions (H⁺) and acetate ions (CH₃COO⁻). The acidic character stems from the ability of the acetate ion to stabilize the negative charge after donating the hydrogen ion, making the acid relatively weak. The stability of the resulting acetate ion contributes to the weak acidic behavior of acetic acid.

Formic acid (HCOOH) is also a weak organic acid that partially dissociates in water, producing hydrogen ions (H⁺) and formate ions (HCOO⁻). Similar to acetic acid, the stability of the formate ion determines the acidic strength. Despite its simple structure, the stability of the formate ion affects the acidity of formic acid, making it moderately stronger than acetic acid.

Citric acid (C₆H₈O₇) is a triprotic acid, meaning it can donate three hydrogen ions successively. Its acidity is due to the release of these hydrogen ions in aqueous solutions. The presence of three ionizable hydrogen atoms influences its acidity. Citric acid is a relatively stronger acid compared to acetic and formic acids due to the multiple hydrogen ions it can donate, contributing to its greater acidic character.