Weak Acid Examples - Definition, Important of Weak Acids, FAQs

Acids

Acids are compounds that can donate a proton (hydrogen ion) to another material by dissolving in water and producing H⁺ ions. Acids are distinguished by their sour flavour. Acids turn blue litmus red by donating H⁺ ions and remaining favourable even after losing H⁺ ions.

Strong acid and weak acid

Weak acids can only be partially ionized in their solutions, but strong acids can be fully ionized when dissolved in water. In comparison to strong acids, weak acids are more routinely used. They are prevalent in everyday life, such as vinegar and lemon juice. When they're dissolved in water, the concentration of the weak acid and its constituent ions reach a point of equilibrium. Acids, bases and Salts can be read in detail from here.

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This Story also Contains

1. Acids
2. Strong acid and weak acid
3. What is a weak acid?
4. Weak mineral acid

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What is a weak acid?

Weak acid definition- A weak acid is an acid that partially dissociates into its constituent ions when dissolved in water. Some weak acids list or weak acid names are given below.

Weak acid examples

• Formic acid (HCOOH)

• Acetic acid (CH₃COOH)

• Benzoic acid (C₆H₅COOH)

• Oxalic acid (C₂H₂O₄)

• Hydrofluoric acid (HF)

• Nitrous acid (HNO₂)

• Sulfurous acid (H₂SO₃)

• Phosphoric acid (H₃PO₄)

Some of the examples of weak acids can be briefly explained as below;

1. Formic Acid.

One of the most basic carboxylic acids is formic acid, commonly known as methanoic acid. HCOOH is the chemical formula for this substance. Formic acid is a weak acid that is found naturally inside the bodies of some ants. Formic acid occurs as a colourless liquid (with occasional vapours) under ordinary temperature and pressure conditions. The density of this chemical is 1.22 grams per millilitre. With water, this weak acid is known to generate a miscible combination.

The pK_a value of this weak acid is found to be 3.745. Formate is the conjugate base that results from the deprotonation of formic acid. Formic acid also creates miscible compositions with a variety of other organic solvents, including acetone, glycerol, ethanol, and methanol. Furthermore, it is known that this molecule is somewhat soluble in aromatic chemicals like benzene and toluene. Formic acid has a molecular mass of 46.025 grams per mole.

2. Acetic Acid

Acetic acid, commonly known as ethanoic acid, is a weak acid having the formula CH₃COOH. It's the active ingredient in vinegar, which is a 4% to 7% acetic acid solution in water. When dissolved in water, acetic acid only partially dissociates into its constituent ions, making it a weak acid. It's worth noting, too, that concentrated acetic acid is known to corrode human skin. This weak acid is reported to exist as a colourless liquid with a strong, vinegar-like odour at typical temperature and pressure conditions.

Acetic acid has a density of 1.049 grams per cubic centimetre when it is liquid. Solid acetic acid, on the other hand, is known to have a higher density, measuring 1.27 grams per cubic centimetre. Acetic acid's melting point is usually between 16 and 17 degrees Celsius. Acetic acid's boiling point is also reported to range between 118 and 110 degrees Celsius. With water, this weak acid is known to generate miscible combinations.

3. Oxalic Acid

Oxalic acid (C₂H₂O₄) is a widely used weak acid. Under typical temperature and pressure circumstances, this organic compound exists as a crystalline solid that is white in colour. The acidity of this molecule is significantly higher than that of acetic acid. The molar mass of the dihydrate of this chemical molecule is 126.06 grams per mole.

Under STP, the density of this chemical is reported to be 1.9 grams per cubic centimeter (in its anhydrous state). The melting point of anhydrous oxalic acid is approximately 190 degrees Celsius. This organic acid is known to be relatively water soluble. Oxalic acid is soluble in water at a temperature of 20 degrees Celsius and has a solubility of 90 to 100 grams per liter.

4. Benzoic Acid

C₆H₅COOH is the chemical formula for benzoic acid, an aromatic carboxylic acid. This substance is a weak acid that can be found in various plants, as well as gum benzoin. Preservatives made from the salts of this weak acid are frequently utilized in the food sector. This chemical has a molecular mass of 122.123 grams per mole. Benzoic acid is known to exist as a crystalline solid with no distinguishable colour at typical temperature and pressure conditions. Benzoic acid has a faintly pleasant odour due to the presence of an aromatic system in the substance.

The density of benzoic acid is approximately 1.26 grams per cubic centimeter under typical temperature and pressure conditions. It should be noted, however, that the solubility of benzoic acid in the water rises with increasing temperature. The solubility of benzoic acid in water increases to 56.31 grams per liter at a temperature of 100 degrees Celsius.

Also Read:

Below are some of the NCERT solutions and NCERT exemplar solutions for Class 12th Chemistry.

• NCERT solutions for Class 12 Chemistry Chapter 12 Aldehydes, Ketones and Carboxylic Acids
• NCERT Exemplar Class 12 Chemistry Solutions Chapter 12 Aldehydes, Ketones and Carboxylic Acids
• NCERT notes Class 12 Chemistry Chapter 12 Aldehydes, Ketones and Carboxylic Acids

5. Hydrofluoric Acid

Hydrofluoric acid (HF) is another example of a weak acid. When dissolved in water, this molecule does not entirely dissociate into hydrogen and fluoride ions, making it a weak acid. However, it is vital to keep in mind that hydrofluoric acid is toxic to humans and that contact with human skin can result in severe burns. A solution of hydrogen fluoride in water (which produces hydrofluoric acid) is colourless. The density of a 48% HF solution in water is estimated to be 1.15 grams per milliliter. The pK_a value of hydrofluoric acid is found to be3.17.

Weak mineral acid

Weak mineral acid is formed from more than one inorganic compounds. Weak mineral acid example is boric acid.

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