---
title: "Formic acid, \\(\\text{HCOOH}\\), ionizes in water according to the equation below.  \\[ \\text{HCOOH(aq)} + \\text{H}_2\\text{O(l)} \\rightleftharpoons \\text{HCOO}^-\\text{(aq)} + \\text{H}_3\\text{O}^+\\text{(aq)} \\]  A student prepares a \\(0.20\\text{ M}\\) aqueous solution of \\(\\text{HCOOH}\\) at \\(25\\ ^\\circ\\text{C}\\). Given that \\(K_a = 1.8 \\times 10^{-4}\\) for \\(\\text{HCOOH}\\) at this temperature, what is the equilibrium concentration of \\(\\text{H}_3\\text{O}^+\\text{(aq)}\\) in the solution?"
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url: "https://nerd-notes.com/ubq/119993/"
date_modified: "2026-08-21T08:31:40+00:00"
---

# Formic acid, \(\text{HCOOH}\), ionizes in water according to the equation below.

\[ \text{HCOOH(aq)} + \text{H}_2\text{O(l)} \rightleftharpoons \text{HCOO}^-\text{(aq)} + \text{H}_3\text{O}^+\text{(aq)} \]

A student prepares a \(0.20\text{ M}\) aqueous solution of \(\text{HCOOH}\) at \(25\ ^\circ\text{C}\). Given that \(K_a = 1.8 \times 10^{-4}\) for \(\text{HCOOH}\) at this temperature, what is the equilibrium concentration of \(\text{H}_3\text{O}^+\text{(aq)}\) in the solution?

Formic acid, \(\text{HCOOH}\), ionizes in water according to the equation below.

\[ \text{HCOOH(aq)} + \text{H}_2\text{O(l)} \rightleftharpoons \text{HCOO}^-\text{(aq)} + \text{H}_3\text{O}^+\text{(aq)} \]

A student prepares a \(0.20\text{ M}\) aqueous solution of \(\text{HCOOH}\) at \(25\ ^\circ\text{C}\). Given that \(K_a = 1.8 \times 10^{-4}\) for \(\text{HCOOH}\) at this temperature, what is the equilibrium concentration of \(\text{H}_3\text{O}^+\text{(aq)}\) in the solution?

- **A.** \(3.6 \times 10^{-5}\text{ M}\)
- **B.** \(6.0 \times 10^{-3}\text{ M}\)
- **C.** \(3.0 \times 10^{-2}\text{ M}\)
- **D.** \(2.0 \times 10^{-1}\text{ M}\)

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/119993/*