Barium Hydroxide Solution: Properties, Uses & FAQs

Barium hydroxide solution is a strongly alkaline aqueous reagent widely used in analytical chemistry, organic synthesis, and laboratory titrations for its ability to provide a stable, high-pH environment and to precipitate sulfate ions quantitatively.

Chemical Formula

Ba(OH)₂

CAS Number

17194-00-6

Nature

Strong inorganic base; fully dissociates in dilute aqueous solution

Aladdin SKU

B432219 (Sigma reference: B4059)

Appearance

Clear to slightly turbid colorless aqueous solution

Primary Hazard

Corrosive; causes severe skin and eye burns; harmful if ingested or inhaled

Storage

Store tightly sealed at room temperature; protect from CO₂ absorption

What Is Barium Hydroxide Solution?

Barium hydroxide solution is an aqueous preparation of barium hydroxide [Ba(OH)₂, CAS 17194-00-6], a strong diprotic inorganic base. In solution, it dissociates completely to yield barium cations (Ba²⁺) and hydroxide anions (OH⁻), producing a strongly alkaline medium. Aladdin Scientific supplies this reagent under SKU B432219 (corresponding to Sigma reference B4059).

The solution is characteristically clear to slightly turbid and colorless. Because barium hydroxide has limited solubility in water (approximately 3.9 g/100 mL at 20 °C for the octahydrate form), commercially supplied solutions are typically prepared at concentrations that remain below saturation to ensure homogeneity. Researchers should verify the exact concentration on the product certificate of analysis before use.

Key Laboratory Applications

Barium hydroxide solution serves multiple roles in research and analytical laboratories:

• Sulfate precipitation and gravimetric analysis: Ba²⁺ reacts quantitatively with sulfate ions (SO₄²⁻) to form insoluble barium sulfate (BaSO₄), making barium hydroxide solution a standard reagent for gravimetric determination of sulfate in water, soil, and industrial samples.
• Acid–base titrations: As a strong dibase, it is used as a primary or secondary standard in titrimetric analysis, particularly for the standardization of acid solutions.
• Organic synthesis: Barium hydroxide solution acts as a mild, selective base in certain condensation reactions (e.g., aldol condensation) and saponification of esters, where softer base conditions are preferred over sodium or potassium hydroxide.
• CO₂ detection and absorption: The formation of a white precipitate of barium carbonate (BaCO₃) upon exposure to carbon dioxide makes barium hydroxide solution (baryta water) a classical qualitative test for CO₂ in gas analysis.
• pH adjustment: Used to raise and control pH in buffers and reaction media when barium ion contamination is acceptable or when sulfate removal is simultaneously desired.

Handling, Safety, and Storage

Hazard classification: Barium hydroxide solution is corrosive and classified as harmful. It causes severe burns to eyes, skin, and mucous membranes. Barium compounds are acutely toxic if ingested or inhaled in significant quantities.

Personal protective equipment (PPE): Always wear chemical-splash goggles, acid/base-resistant gloves (e.g., nitrile or neoprene), and a laboratory coat when handling this reagent. Work in a fume hood or well-ventilated area if aerosolization is possible.

First aid: In case of skin or eye contact, flush immediately with large amounts of water for at least 15 minutes and seek medical attention. For ingestion, do not induce vomiting; seek immediate medical assistance.

Storage: Store in a tightly sealed container at room temperature, away from acids and CO₂-rich atmospheres. Exposure to atmospheric CO₂ gradually converts Ba(OH)₂ to BaCO₃, causing precipitation and reducing effective alkalinity. Refrigeration may cause precipitation of Ba(OH)₂ due to decreased solubility.

Disposal: Dispose of barium-containing waste according to local hazardous waste regulations. Do not pour down the drain without neutralization and verification that barium levels meet local discharge limits.

Ordering and Procurement Information

Aladdin Scientific supplies barium hydroxide solution under SKU B432219, referenced to Sigma catalog number B4059. Procurement teams and lab managers should note the following:

• Specification verification: Request a current certificate of analysis (CoA) to confirm concentration, purity grade, and lot-specific test results prior to placing orders for critical analytical work.
• Packaging: Available pack sizes may vary; contact Aladdin Scientific sales or consult the product page for current available quantities and pricing.
• Shipping: As a corrosive liquid, barium hydroxide solution is subject to hazardous materials shipping regulations (IATA/DOT). Ensure your institution is equipped to receive corrosive reagents and that appropriate secondary containment is in place upon receipt.
• Returns and quality issues: Report any quality discrepancies, damaged shipments, or incorrect products to Aladdin Scientific customer service promptly upon receipt. Refer to the returns and refunds policy on the Aladdin Scientific website for eligibility and procedures.

Frequently asked questions

What concentration is Aladdin's barium hydroxide solution (SKU B432219)?

The exact concentration is specified on the product certificate of analysis (CoA) for each lot. Please request the current CoA from Aladdin Scientific or check the product page for lot-specific concentration data, as this may vary between batches.

Why does my barium hydroxide solution become cloudy over time?

Cloudiness is caused by absorption of atmospheric carbon dioxide (CO₂), which reacts with Ba(OH)₂ to form insoluble barium carbonate (BaCO₃): Ba(OH)₂ + CO₂ → BaCO₃↓ + H₂O. To prevent this, always store the solution in a tightly sealed container and minimize headspace exposure to air. For highly sensitive applications, use freshly opened or freshly prepared solution.

Can barium hydroxide solution be used as a primary standard for acid–base titrations?

Barium hydroxide solution can serve as a titrant for acid standardization, but its use as a primary standard requires careful preparation and standardization against a certified primary standard acid (such as potassium hydrogen phthalate, KHP). The tendency of the solution to absorb CO₂ from the air means its effective concentration can change over time, so periodic restandardization is recommended for high-accuracy work.

Is barium hydroxide solution compatible with sulfate-containing buffers or media?

No. Barium ions (Ba²⁺) react immediately and quantitatively with sulfate ions (SO₄²⁻) to precipitate barium sulfate (BaSO₄, Ksp ≈ 1.1 × 10⁻¹⁰ at 25 °C). Mixing barium hydroxide solution with sulfate-containing reagents will result in precipitation and loss of both barium and sulfate from solution. Ensure all glassware and reagents are sulfate-free before use.

What personal protective equipment (PPE) is required when handling barium hydroxide solution?

At minimum, wear chemical-splash safety goggles, acid/base-resistant gloves (nitrile or neoprene recommended), and a laboratory coat. If there is a risk of aerosol generation, work in a fume hood. Always consult the Safety Data Sheet (SDS) for SKU B432219 for complete hazard and PPE guidance specific to the supplied formulation.

References

1. Sigma-Aldrich (MilliporeSigma). Barium hydroxide solution, catalog number B4059. Product information and Safety Data Sheet.
2. Lide, D. R. (Ed.). CRC Handbook of Chemistry and Physics, 97th Edition. CRC Press. Physical and chemical data for barium hydroxide.
3. Skoog, D. A.; West, D. M.; Holler, F. J.; Crouch, S. R. Fundamentals of Analytical Chemistry, 9th Edition. Cengage Learning. Chapters on gravimetric analysis and acid–base titrimetry.

Products are supplied for research and development use only. Not for use in humans, animals, diagnosis, or therapy.