Boric Acid Uses

What is Boric Acid (H3BO3)?

Boric Acid is a monobasic Lewis acid with the chemical formula H3BO3.

It is an acid-containing compounds of boron, oxygen, and hydrogen. Boric acid is also known as acidum boricum, hydrogen borate, boracic acid, and orthoboric acid. It is a weak acid and has antiviral, antifungal, and antiseptic properties.

Boric acid is soluble in water and does not have any characteristic odour. Under standard conditions, this compound exists either as a colourless crystal or in a white powdery form. Boric acid can be prepared by reacting borax with hydrochloric acid. It can be noted that Wilhelm Homberg was the first person to prepare boric acid from borax.

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Boric Acid as a Medicine

Boric acid is widely used as an antiseptic for the treatment of minor cuts and burns. Furthermore, this compound is also used in medical dressings and salves. Very dilute solutions of boric acid can be used as an eyewash. Owing to its antibacterial properties, boric acid can also be used for the treatment of acne in humans. In its powdered form, it can also be sprinkled into socks and shoes to prevent the athlete’s foot (tinea pedis).

It is important to note that boric acid can prove poisonous if consumed or inhaled in relatively large quantities. Furthermore, continued exposure to boric acid over long durations of time can severely damage the kidney.

Learn about the chemical formulae of various other chemical compounds here.

Preparation of Boric Acid

One of the simplest methods of preparing boric acid is by reacting borax with any mineral acid (hydrochloric acid, for instance). The chemical equation for this reaction can be written as:

Na2B4O7.10H2O + 2HCl → 4H3BO3 + 5H2O + 2NaCl

Boric acid can also be prepared from the hydrolysis of diborane and trihalides of boron (such as boron trichloride or boron trifluoride).

Properties of Boric Acid – H3BO3

H3BO3 Boric Acid
Molecular Weight/ Molar Mass 61.83 g·mol−1
Density 1.435 g/cm3
Boiling Point 158 °C
Melting Point 300 °C

Under standard conditions for temperature and pressure (STP), boric acid exists as a white, crystalline solid that is fairly soluble in water. The solubility of H3BO3 in water is temperature-dependent. At a temperature of 25 °C, the solubility of boric acid in water is 57 g/L. However, when the water is heated to 100 °C, the solubility of this compound increases to approximately 275 g/L. It can also be noted that boric acid is sparingly soluble in pyridine and slightly soluble in acetone. The conjugate base of boric acid is the borate anion. 

The acidity of solutions of boric acid is known to increase with polyols containing cis-vicinal diols (like mannitol and glycerol). The value of pK of B(OH)3 is known to extend to five orders of magnitude (from 9 to 4), under different concentrations of mannitol. It can be noted that in the presence of mannitol, the solution of boric acid with increased acidity can be referred to as mannitoboric acid.

Structure of H3BO3 Molecules

Each boric acid molecule features boron-oxygen single bonds. The boron atom occupies the central position and is linked to three hydroxide groups. The overall molecular geometry of boric acid is trigonal planar. The structure of H3BO3 molecules is illustrated below. 

Boric acid Structure

Structure of Boric acid

What are the Uses of Boric Acid?

The uses of boric acid are listed below.

  • It is used in the manufacture of textile fibreglass
  • It is used in the production of the flat panel display
  • It is used to neutralize the active hydrofluoric acid
  • It is used by blacksmiths as welding flux
  • It is used in electroplating
  • It is used in the jewellery industry
  • It is used in the manufacture of silly putty
  • It is used as an Insecticidal
  • It is used as an antiseptic and antibacterial
  • It is used on carrom boards as a dry lubricant
  • It is used as a neutron poison in some nuclear plants
  • It is used to preserve grains like wheat and rice

In the list of the chemical additives that are used for hydraulic fracturing (also known as fracking), it is not uncommon for boric acid to be present. This compound is also used as a cross-linking and gelling agent in combination with guar gum and is known to regulate the viscosity and rheology of the drilling fluid which is pumped at high pressure in wells. Furthermore, it is of vital importance to regulate the fluid viscosity that helps to keep the grains of the propping agents suspended for long transport distances in order to keep the cracks in the shales sufficiently open. It facilitates the extraction of gas after relieving the hydraulic pressure.

Boric Acid Poisoning

This substance can cause acute or chronic poisoning. When someone takes powdered roach-killing items containing boric acid, they get acute boric acid poisoning. The consequences of ingesting a substantial dose of boric acid can be severe in many areas of the body. After swallowing boric acid, damage to the oesophagus and stomach persists for several weeks. Complications might take months to manifest and lead to death.

There are no histories of long-term respiratory consequences due to exposure to borax as per studies. Long-term intake of boric acid, on the other hand, has been linked to nausea, diarrhoea, and stomach discomfort. Headaches, fever, tremors, twitching, a lack of energy, and weakness are common side effects. Since 1946, borax has been used as an insecticide in the United States under varying limits. According to two EPA records dealing with boric acid and borax, all limits were abolished in February 1986 due to the low toxicity of borax.

Also, Read:

Uses of Nitric Acid Chemical Reactions
Uses of Phosphoric Acid Oxyacids and Ammonia

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Frequently Asked Questions – FAQs


Is boric acid the same as borax?

In fact, borax and boric acid are the same thing and are usually associated with producing homemade laundry soap. All of these materials contain the boron element. Borax is commonly extracted from tourmaline, kernite, and colemanite and is refined. Mineral sassolite is extracted from boric acid.


What is boric acid used for?

Boric acid is also used in many chemical products as an antiseptic, insecticide, flame retardant, neutron absorber, or precursor.


How do you neutralize boric acid?

The acidic and fundamental properties of both the acid and base are damaged by neutralization. Lime and baking soda are two inexpensive chemicals that neutralize acids, which are readily available.


What exactly is boric acid?

Boric acid, often known as hydrogen borate, boracic acid, orthoboric acid or acid boricum, is a weak boron acid sometimes used as an antiseptic, insecticide, flame retardant, or neutron absorber, and as a precursor to other chemical compounds.


Is boric acid soluble in acetone?

Boric acid is a crippling poison. It is sparingly soluble in pyridine and slightly soluble in acetone in water, glycerol, ether, alcohol, methanol, and liquid ammonia. Boric acid can be derived from borax, or by hydrolysing of halides or hydrides of boron. Crystals of boron oxide are slightly soluble in cold water and soluble in hot water.

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