Which is a stronger acid?
c. CH₃OCH₂CH₂CH₂OHorCH₃CH₂OCH₂CH₂OH
d.

Verified step by step guidance

1. Step 1: Analyze the molecular structures provided in the image. Both compounds (i) and (ii) are carboxylic acids, but they differ in the position of the hydroxyl group (-OH) relative to the carbonyl group (C=O). In (i), the hydroxyl group is on the second carbon, while in (ii), it is on the third carbon.
2. Step 2: Understand the concept of inductive effects. Electronegative groups like the hydroxyl group (-OH) can withdraw electron density through sigma bonds, stabilizing the conjugate base of the acid and increasing its acidity. The closer the electronegative group is to the acidic proton, the stronger the inductive effect.
3. Step 3: Compare the proximity of the hydroxyl group to the carboxylic acid functional group in both molecules. In compound (i), the hydroxyl group is closer to the carboxylic acid group, which means it will exert a stronger inductive effect compared to compound (ii).
4. Step 4: Predict the relative acidity based on the inductive effect. Since the hydroxyl group in compound (i) is closer to the acidic proton, it will stabilize the conjugate base more effectively, making compound (i) a stronger acid than compound (ii).
5. Step 5: Conclude that the position of the hydroxyl group significantly influences the acidity of the molecule due to the inductive effect. Compound (i) is the stronger acid compared to compound (ii).

Key Concepts

Acidity and pKa

Acidity in organic chemistry is often measured by the pKa value, which indicates the strength of an acid. A lower pKa value corresponds to a stronger acid, meaning it can donate protons (H+) more readily. Understanding the relationship between structure and acidity is crucial, as factors like electronegativity and resonance can significantly influence pKa values.

Inductive Effect

The inductive effect refers to the electron-withdrawing or electron-donating influence of substituents on a molecule. Electronegative atoms or groups can stabilize the negative charge on the conjugate base of an acid, enhancing its acidity. In the comparison of acids, the presence of electron-withdrawing groups can lead to increased acidity due to this effect.

Resonance Stabilization

Resonance stabilization occurs when a molecule can be represented by multiple valid Lewis structures, allowing for the delocalization of electrons. This delocalization can stabilize the conjugate base formed after an acid donates a proton, making the original acid stronger. Analyzing the structures of the compounds in the question will reveal how resonance affects their acidity.