Certainly! Let's break down the problem step by step. --- ## **Question Restatement** You're asked to: 1. **Place an arrow** showing which way the equilibrium lies for the acid-base reaction. 2. **Show your reasoning** by comparing acid/base strength on each side. --- ## **Given Reaction** ``` C≡C-H + Benzene⁻ ⟶⬜⟶ Benzene + C≡C⁻ (alkyne) (conjugate base) (benzene) (acetylide ion) ``` --- ## **Step 1: Identify Acids and Bases** - **Left Side:** - **Acid:** Alkyne (C≡C-H), because it has a proton to donate. - **Base:** Benzene anion (Benzene⁻), because it can accept a proton. - **Right Side:** - **Acid:** Benzene, because it has gained a proton. - **Base:** Acetylide ion (C≡C⁻), because it has lost a proton. --- ## **Step 2: Compare Acid Strengths (pKa Values)** - **Alkyne (C≡C-H):** pKa ≈ 25 - **Benzene:** pKa ≈ 43 **Lower pKa = Stronger Acid** - **Alkyne (pKa 25)** is a much **stronger acid** than **benzene (pKa 43)**. --- ## **Step 3: Compare Base Strengths** - **Conjugate base of alkyne (acetylide ion, C≡C⁻):** Strong base. - **Conjugate base of benzene (benzene anion):** Extremely strong base. **The weaker base is the conjugate base of the stronger acid.** - **Acetylide ion (C≡C⁻)** is **weaker** than **benzene anion**. --- ## **Step 4: Which Way Does the Equilibrium Lie?** **Equilibrium favors the formation of the weaker acid and weaker base.** - **Weaker acid:** Benzene (pKa 43) - **Weaker base:** Acetylide ion (C≡C⁻) **So the equilibrium lies to the right**. --- ## **Step 5: Draw the Arrow** - Draw the equilibrium arrow pointing **to the right** (from left to right). --- ## **Summary Table** | Side | Acid | pKa | Base | Strength | |----------------|---------------|-----|------------------|-------------| | Left | Alkyne | 25 | Benzene anion | Strong base | | Right | Benzene | 43 | Acetylide ion | Weak base | --- ### **Conclusion** - **Draw the arrow to the right.** - **Reason:** The equilibrium favors formation of the weaker acid (benzene, pKa 43) and the weaker base (acetylide ion, C≡C⁻). If you need help with the arrow illustration or more details, let me know!