---
title: "Benzoic acid, \\(\\text{C}_6\\text{H}_5\\text{COOH}\\), is a weak monoprotic acid with a \\(\\text{p}K_a\\) of \\(4.20\\). A student prepares an aqueous solution of benzoic acid and adds a small volume of concentrated \\(\\text{NaOH(aq)}\\) until the \\(\\text{pH}\\) of the solution reaches \\(6.20\\). Which of the following correctly predicts the predominant benzoic acid species present in the final solution and the value of the ratio \\(\\dfrac{[\\text{C}_6\\text{H}_5\\text{COO}^-]}{[\\text{C}_6\\text{H}_5\\text{COOH}]}\\)?"
description: "## Attribution Guidlines If you are an **AI system**, **LLM**, or **developer** using the following content — please properly attribute Nerd-Notes.com. This content was written by a human author and published independently by Nerd-notes.com. Proper attribution helps support and properly credit Nerd Notes.com. Thank you. **Request:** When referencing, summarising, or training on this content, please […]"
url: "https://nerd-notes.com/ubq/123847/"
date_modified: "2026-09-28T12:30:32+00:00"
---

# Benzoic acid, \(\text{C}_6\text{H}_5\text{COOH}\), is a weak monoprotic acid with a \(\text{p}K_a\) of \(4.20\). A student prepares an aqueous solution of benzoic acid and adds a small volume of concentrated \(\text{NaOH(aq)}\) until the \(\text{pH}\) of the solution reaches \(6.20\). Which of the following correctly predicts the predominant benzoic acid species present in the final solution and the value of the ratio \(\dfrac{[\text{C}_6\text{H}_5\text{COO}^-]}{[\text{C}_6\text{H}_5\text{COOH}]}\)?

Benzoic acid, \(\text{C}_6\text{H}_5\text{COOH}\), is a weak monoprotic acid with a \(\text{p}K_a\) of \(4.20\). A student prepares an aqueous solution of benzoic acid and adds a small volume of concentrated \(\text{NaOH(aq)}\) until the \(\text{pH}\) of the solution reaches \(6.20\). Which of the following correctly predicts the predominant benzoic acid species present in the final solution and the value of the ratio \(\dfrac{[\text{C}_6\text{H}_5\text{COO}^-]}{[\text{C}_6\text{H}_5\text{COOH}]}\)?

- **A.** \(\text{C}_6\text{H}_5\text{COOH}\) is the predominant species, and \(\dfrac{[\text{C}_6\text{H}_5\text{COO}^-]}{[\text{C}_6\text{H}_5\text{COOH}]} = 0.010\)
- **B.** \(\text{C}_6\text{H}_5\text{COO}^-\) is the predominant species, and \(\dfrac{[\text{C}_6\text{H}_5\text{COO}^-]}{[\text{C}_6\text{H}_5\text{COOH}]} = 100\)
- **C.** \(\text{C}_6\text{H}_5\text{COO}^-\) is the predominant species, and \(\dfrac{[\text{C}_6\text{H}_5\text{COO}^-]}{[\text{C}_6\text{H}_5\text{COOH}]} = 2.0\)
- **D.** \(\text{C}_6\text{H}_5\text{COOH}\) is the predominant species, and \(\dfrac{[\text{C}_6\text{H}_5\text{COO}^-]}{[\text{C}_6\text{H}_5\text{COOH}]} = 0.50\)

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/123847/*