Boric Acid Overview: Properties, Uses, Safety & Buying Guide
In this guide, we’ll explore boric acid’s chemical profile, key applications, safety considerations, and how to source it in the appropriate grade and purity.
Boric Acid Overview
Boric acid, also known as orthoboric acid or hydrogen borate (H3BO3), is a white crystalline compound built from a single boron atom bonded to three hydroxyl groups. It's a weak acid valued for its buffering, antimicrobial, and insecticidal properties, and this page is the chemistry and sourcing reference: formula, structure, molecular weight, physical properties, grades, and safety data all in one place. For the full breakdown of what boric acid is actually used for across industries, see Boric Acid: Uses and Applications, this page stays focused on what boric acid is.
Key Facts About Boric Acid
|
Property |
Value |
|
Synonyms |
Hydrogen borate, orthoboric acid, acidum boricum, boracic acid |
|
Chemical Formula |
H3BO3 |
|
CAS Number |
10043-35-3 |
|
Molar Mass |
61.83 g/mol |
|
Appearance |
White, crystalline powder or granules |
Molecular Structure
Orthoboric acid is built around a single boron atom bonded to three hydroxyl (OH) groups arranged in a trigonal planar geometry, roughly 120 degrees apart, the same flat, three-around-one arrangement seen in other trigonal planar molecules. Each molecule can hydrogen bond to its neighbors through those hydroxyl groups, and in the solid crystal, this creates flat sheets of hydrogen-bonded H3BO3 molecules stacked loosely on top of each other, similar in concept to the layered structure of graphite, which is part of why boric acid crystals have a soft, slightly slippery, flaky feel.
This layered hydrogen-bonded structure also explains its behavior on heating: rather than melting cleanly, boric acid progressively loses water as temperature rises, first converting to metaboric acid (HBO2) and eventually to boron trioxide (B2O3) at higher temperatures still, a stepwise dehydration rather than a simple phase change.
Physical and Chemical Properties
|
Property |
Value |
|
Physical State |
Solid; white crystalline powder or flakes |
|
Melting/Decomposition Point |
170.9°C (dehydrates to metaboric acid rather than melting cleanly) |
|
Boiling Point |
Not applicable; decomposes before boiling |
|
Solubility in Water |
Soluble; approximately 47 g/L at 25°C |
|
pH (0.1 M solution) |
Approximately 5.1 |
|
Reactivity |
Reacts with strong bases and certain metals to form borates |
|
Hygroscopicity |
Mildly hygroscopic |
|
Stability |
Stable under normal conditions; degrades when heated or exposed to strong bases |
These properties, low volatility, mild acidity, and consistent water solubility, are what make boric acid useful across such a wide range of formulations, from buffering systems to flame retardants, without requiring exotic handling.
Lab Alley supplies boric acid to consumers, laboratories, manufacturers, research institutions, and industrial operations nationwide. Our boric acid meets high standards of purity, making it suitable for diverse uses including household cleaning, pharmaceutical and medical formulations, industrial manufacturing, scientific research, and agriculture and pest control.We offer boric acid in convenient packaging sizes, with additional bulk quantities available upon request.To place an order or learn more about custom sizes and pricing, call Lab Alley at 512-668-9918.
Uses & Benefits
What Is Boric Acid Used For?
In short: pharmaceuticals and eye care (antiseptic eye washes, topical ointments), industrial manufacturing (glass and ceramics, corrosion inhibition, flame retardants), agriculture and pest control (micronutrient fertilizer, insecticide baits), household cleaning, and laboratory buffer solutions. Each of these applications calls for a different grade and purity, and the full detail on how boric acid functions in each of these use cases, including specific formulations, dosing in agricultural contexts, and household application guidance, lives on the dedicated Boric Acid: Uses and Applications page rather than being duplicated here.
Grades We Carry
Lab Alley currently stocks boric acid in two purity tiers:
|
Grade |
Purity |
Typical Use |
|
ACS Grade (Crystal or Granular) |
99.8% |
Analytical chemistry, research requiring official ACS purity standards |
|
Lab Grade (Powder, Mesh 100) |
99% |
General lab work, educational use, formulation work without a strict purity standard requirement |
Solutions are also available preformulated (1 Molar and saturated solutions, plus a 4% Lab Grade solution) for applications that call for a ready-to-use dilution rather than powder to be measured and dissolved in house. Every grade ships with a Safety Data Sheet, and a Certificate of Analysis is available on request.
Choosing the wrong tier matters more than people expect: analytical work specified for ACS Grade that gets substituted with Lab Grade introduces exactly the purity variability the ACS standard exists to rule out, since Lab Grade carries no such compliance guarantee. Spec the grade the application actually requires rather than defaulting to whichever is cheaper.
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Safety Information
Boric acid is generally low in toxicity, but concentrated or industrial forms still require careful handling.
Health Hazards:
-
Inhalation: may cause throat irritation, coughing, or discomfort in dusty conditions.
-
Skin contact: prolonged contact can cause irritation or rash.
-
Eye contact: dust or solution may cause redness, tearing, or stinging.
-
Ingestion: toxic in large quantities; may cause nausea, vomiting, or organ damage.
Long-term exposure to high levels of boric acid, particularly in industrial settings, has been associated with reproductive and developmental risk in animal studies, which is reflected in its EU classification as a reproductive toxicant at sustained high exposure. Always review the current SDS for the specific grade in use.
Personal Protective Equipment:
-
Lab handling or small quantities: gloves, goggles, and a dust mask if working with powders.
-
Industrial bulk handling: protective clothing, chemical-resistant gloves, full-face protection if dust is present.
Spill, Storage, and Disposal:
-
Spill response: sweep up dry spills gently to avoid raising dust; use a HEPA vacuum for fine material.
-
Storage: sealed containers, away from moisture and incompatible chemicals.
-
Disposal: follow local environmental guidelines; neutralize small quantities when appropriate.
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