Weak Acid Examples: Overview, Questions, Preparation

This chapter has multiple topics listed below:

Acids, Bases and Salts Acid Strength Difference between Acid and Bas...Examples of Bases Zinc carbonate Zinc Nitrate Aluminium Phosphate Aspartic Acid Butyric Acid Tannic acid Uses of Folic Acid Uses of Acetic Acid Lactic Acid formula Uses of Citric Acid Magnesium Nitrate Barium Iodide Dilute Acids Magnesium Phosphate Uses of Hydrochloric Acid List of Strong Acids Butanoic Acid Sodium Chlorate Barium Carbonate Chloroacetic Acid Magnesium Bicarbonate Red Cabbage Indicator Sodium Hexametaphosphate Zinc Hydroxide Potassium Iodate Peroxydisulfuric Acid Ph of Acids and Bases Potassium Bromate Weak Acid Examples Weak Bases Magnesium Hydroxide Monosodium Glutamate Potassium Hydroxide Nitrous Acid Henderson Hasselbalch Equation Difference between Alkali and B...Properties of Bases Sodium Citrate Ammonium Phosphate Chemical Indicators Chromic Acid Perchloric Acid Uses of Sodium Hydroxide Zinc Acetate

Yamini Saini

Updated on Jun 30, 2021 04:53 IST

Weak acids are acids that, when dissolved in liquids, do not properly dissociate into their constituent ions. An equilibrium is formed between the concentration of the weak acid and its constituent ions when dissolved in water. Below are some typical examples of weak acids.

Formic acid (HCOOH)

Acetic acid (CH3COOH)

Benzoic acid (C6H5COOH)

Oxalic acid (C2H2O4)

Hydrofluoric acid (HF)

Below is a short overview of the properties of each of these weak acids.

Table of Contents

Formic Acid
Acetic Acid
Weak Acid Examples in Class 10
Illustrated Examples
FAQs on Weak Acids

Formic Acid

One of the simplest carboxylic acids is formic acid, also referred to as methanoic acid. This compound’s chemical formula is HCOOH or CH2O2. Formic acid is a notable example of a weak acid and is believed to exist spontaneously within certain ants’ bodies. Formic acid occurs as a colourless liquid under normal temperature and pressure conditions (which sometimes evolves fumes). Formic acid is known to contain a heavy and penetrating pungent odour in its liquid state.

Properties of Formic Acid

Molar mass	46.025 grams per mole
pKa	3.745
Melting point	8.4C
Boiling point	100.8C
Density	1.22 grams per millilitre

Acetic Acid

Acetic acid, also known as ethanoic acid, has the molecular formula CH3COOH and is a mild acid. Vinegar, which is a 4-7 per cent acetic acid solution in water, is considered to be the active ingredient. Acetic acid is a weak acid and when it is dissolved in water, it only partly dissociates into its constituent ions. It is important to remember that distilled acetic acid is recognised as corrosive to human skin.

Properties of Acetic Acid

Molar mass	60.052 grams per mole
pKa	4.756
Melting point	16C to 17C
Boiling point	118C to 110C
Density	1.049 grams per cubic centimetre(liquid) and 1.27 grams per cubic centimetre(solid)

Weak Acid Examples in Class 10

This concept is taught under the chapter ‘Acids, Bases, and Salts.’ In this chapter, you will be taught about the various weak acids and their properties. The weightage is 3 marks.

Illustrated Examples

What pH levels do weak acids have?

A pH range of around 5 to just below 7.

Is alcohol basic or acidic?

By the Arrhenius concept of acid and base, alcohol is neither acidic nor basic when dissolved in water since it neither creates H+ nor OH- in the solution.

Is oxalic acid weak or strong acid?

In an aqueous solution, oxalic acid is a mild acid that can ionise. Oxalic acid is a mild acid, and in an aqueous solution, it can only partly ionise.

FAQs on Weak Acids

Q. Is lemon juice a weak acid?

A. There are two acids in lemon juice, but only one of them is a key player in the fruit’s acidity. Lemon juice is about 5-8 per cent citric acid. Citric acid is a weak acid that accounts for the lemons’ sour taste. Lemons also contain vitamin C or ascorbic acid.

Q. Is HCl a weak acid?

A. Hydrogen chloride (HCl) ionises fully in water into hydrogen ions and ions of chloride. A weak acid is an acid, which, in an aqueous solution, ionises only slightly.

Q. Is baking soda a weak acid?

A. Baking soda consists of sodium bicarbonate with the formula NaHCO 3 , a chemical compound. The most familiar alkali used in cooking is currently sodium bicarbonate (baking soda). It is the salt of a powerful alkali and a weak acid that functions as a weak alkali.

Q. Is orange juice a weak or strong acid?

A. The use of acid-base balance is involved in Orange Juice. With a pH of 3, Orange Juice itself is very acidic. Citric acid is a crucial ingredient that supplies vitamin C in the orange. Citric acid is a weak acid (C 6 H 8 O 7 ), although, in liquids such as water, weak acids are only partly ionised.

Q. Why is HCl a strong acid?

A. HCl is a strong acid, and it nearly fully dissociates.