what reacts with borax

Chemical Reactions with Borax: Find Out What Reacts with This Popular Household Compound

By Melissa JacksonFebruary 2, 2026

Borax, a naturally occurring mineral compound, is a versatile substance with a wide range of uses, from household cleaning to scientific research. One of its most notable features is its ability to react with various substances, leading to a broad spectrum of chemical changes. This article explores the key reactants of borax and the chemical processes involved.

Borax's chemical formula is Na2B4O7·10H2O, and it's a salt of boric acid. Its reactivity stems from the polyborate ions it forms in water. Let's delve into the substances that react with borax and the results of these reactions.

Acids and Bases

Borax reacts with both acids and bases, altering its structure and resulting in new compounds.

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In aqueous solutions, borax dissociates into sodium ions (Na+) and tetraborate ions (borate ions or [B4O7]2-). When it comes into contact with an acid, borax reacts to form boric acid and sodium ions.

Acid-Borax Reactions

Borax's reaction with acids produces a weak acid called boric acid (H3BO3). This reaction is represented by the balanced chemical equation:

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

In this reaction, hydrochloric acid (HCl) reacts with borax (Na2B4O7·10H2O) to produce boric acid (H3BO3), sodium chloride (NaCl), and water (H2O).

Base-Borax Reactions

Borax also reacts with bases to form complex borates. For instance, it reacts with sodium hydroxide (NaOH) to produce sodium borate:

Na₂B₄O₇.10H₂O + 2NaOH → 2Na₂B₂O₄ + 12H₂O

In this reaction, sodium hydroxide reacts with borax to form sodium metaborate (Na2B2O4) and water.

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Sunlight and UV Radiation

Borax's reaction with light, particularly ultraviolet (UV) radiation, is a phenomenon that has been harnessed for fluorescent lighting and other applications.

Borax, when combined with certain other compounds and exposed to UV light, exhibits fluorescence. This is due to the excitation of electrons in the borate ions, which then emit light of a longer wavelength when they return to their ground state.

Borax Fluorescence

Borax's fluorescence is most commonly observed in borax-based UVC lamps. These lamps use a mercury-vapor discharge to produce UV light, which excites borate ions in the borax. The borate ions subsequently emit visible light, often in the purple or blue spectrum.

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UV-Borax Reactions in Sunscreen

In skincare products, borax react with UV radiation to protect the skin. When borax is incorporated into sunscreen formulations, it helps absorb and filter out harmful UV-A and UV-B rays, preventing skin damage and sunburns.

Borax's reactivity and versatility make it a compelling compound for various industries and scientific applications. Its reactions with acids, bases, and light are just a few examples of the numerous chemical changes it undergoes. As our understanding of borax's properties continues to grow, so too will its potential uses in everyday life and cutting-edge technology.