Rank these compounds in order of increasing acid strength.

Verified step by step guidance

1. Step 1: Analyze the molecular structures of the compounds (A, B, C, and D). Note the presence of functional groups, electronegative atoms, and resonance effects that influence acidity.
2. Step 2: Consider the inductive effect. Compound B contains trifluoromethyl groups (-CF3), which are highly electronegative and withdraw electron density through the inductive effect, stabilizing the conjugate base and increasing acidity.
3. Step 3: Evaluate resonance effects. Compound C and D have additional carbonyl groups that can participate in resonance stabilization of the conjugate base, making them more acidic than compound A.
4. Step 4: Compare compound A and C. Compound C has an extra carbonyl group compared to A, which increases its ability to stabilize the conjugate base through resonance, making it more acidic than A.
5. Step 5: Rank the compounds in order of increasing acid strength based on the combined effects of resonance and inductive stabilization: A < C < D < B.

Key Concepts

Acid Strength

Acid strength refers to the ability of a compound to donate protons (H+) in a solution. Stronger acids dissociate more completely in water, resulting in a higher concentration of H+ ions. Factors influencing acid strength include the stability of the conjugate base, electronegativity of atoms, and resonance stabilization. Understanding these factors is crucial for ranking acids.

Conjugate Base Stability

The stability of a conjugate base is a key determinant of acid strength. A more stable conjugate base corresponds to a stronger acid, as it can better accommodate the negative charge after proton donation. Factors such as electronegativity, size of the atom bearing the charge, and resonance can enhance conjugate base stability, thus influencing the acid's strength.

Resonance Effects

Resonance effects occur when a molecule can be represented by multiple valid Lewis structures, leading to delocalization of electrons. In the context of acids, resonance can stabilize the conjugate base by spreading out the negative charge over multiple atoms. This increased stability often results in a stronger acid, making resonance a critical concept in acid strength comparisons.