---
title: "Carboxylic Acids, Esters and Hydrolysis"
description: "Carboxylic acids are weak acids that still fizz with carbonates, and with an alcohol they form an ester in a reaction that never quite finishes. Hydrolysis runs the ester back, in acid or in alkali."
canonical: https://lightmysky.com/learn/science/carboxylic-acids-esters-and-hydrolysis-mt_QLxUs5cOH2
source: https://lightmysky.com/learn/science/carboxylic-acids-esters-and-hydrolysis-mt_QLxUs5cOH2.md
retrieved: 2026-09-12
---

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# Carboxylic Acids, Esters and Hydrolysis

Carboxylic acids are weak acids that still fizz with carbonates, and with an alcohol they form an ester in a reaction that never quite finishes. Hydrolysis runs the ester back, in acid or in alkali.

Subject: Science · Area: Chemistry · Ages 17 to 18
Page: https://lightmysky.com/learn/science/carboxylic-acids-esters-and-hydrolysis-mt_QLxUs5cOH2

## Ready when they can

- Writes the reactions of a carboxylic acid with a carbonate, with a metal and with an alkali
- Explains why a carboxylic acid counts as weak and is still acidic enough to release carbon dioxide
- Writes esterification with its catalyst and explains why the yield is limited
- Compares acid hydrolysis with alkaline hydrolysis of an ester and gives a use for each

## Lesson: Acids, esters and hydrolysis

Pour vinegar onto baking soda and it fizzes at once. Vinegar carries acetic acid and baking soda is a carbonate, and acid plus carbonate gives a salt plus water plus carbon dioxide.

Acetic acid is weak, with only about 1 in 100 split at a time, yet the fizz still finishes. Each used-up H+ is topped up from the waiting molecules, so weak never meant too weak to react.

**Example.** Stir acetic acid with ethanol and you get ethyl acetate, the fruity ester, plus water. An acid catalyst starts the reaction off, but it also runs backwards, so the yield never completes.

**Tip.** Hydrolysis runs the ester back. With acid you get the carboxylic acid and the alcohol again, while with sodium hydroxide you get the salt instead, which is the route from fats to soap.

**Recap.** Weak acids still fizz with carbonates, ester-making never finishes, and hydrolysis choice decides salt or acid.

## Practice

8 questions on this page, each with its working shown.

## Needs first

- [The Equilibrium Constant Kc](https://lightmysky.com/learn/science/the-equilibrium-constant-kc-mt_3G8b6Hyz3u)
- [Aldehydes and Ketones: Nucleophilic Addition and the Tests That Separate Them](https://lightmysky.com/learn/science/aldehydes-and-ketones-nucleophilic-addition-and-the-tests-that-separate-them-mt_bVcJ0UaXk6)
- [Weak Acids, Ka and pKa](https://lightmysky.com/learn/science/weak-acids-ka-and-pka-mt_q7fYb7qzMH)

## Opens up

- [Nucleophilic Acyl Substitution and the Reactivity Ladder](https://lightmysky.com/learn/science/nucleophilic-acyl-substitution-and-the-reactivity-ladder-mt_b60fq2aQ7r)
- [Amines and Amides: Basicity and the Nitrogen Functional Groups](https://lightmysky.com/learn/science/amines-and-amides-basicity-and-the-nitrogen-functional-groups-mt_cGP3ZJ8S6h)
- [Addition and Condensation Polymers](https://lightmysky.com/learn/science/addition-and-condensation-polymers-mt_klu208vTI1)