When sourcing chemicals for large-scale industrial operations, every specification matters — and sodium metabisulfite density g/ml is a parameter that directly impacts logistics, storage design, and process accuracy. Whether you are a procurement manager for a water treatment plant, a mining chemicals buyer, or a laboratory technician preparing a sickling test solution, understanding the physical properties of this compound is essential for cost-effective and safe handling. In this comprehensive guide, we detail the density, molecular weight, solubility, and other key properties of sodium metabisulfite (Na2S2O5), compare it with sodium bisulfite, and explain how these data points influence your purchasing decisions.
Sodium metabisulfite is a white or yellowish crystalline powder with a density of approximately 1.48 g/cm³ (equivalent to 1.48 g/ml). While this value might seem like a minor technical detail, it carries significant weight in several areas of industrial supply and usage.
Bulk orders are priced by weight, but the physical volume they occupy depends on density. With a bulk density typically ranging from 1.1 to 1.3 g/cm³ in loose fill, a 25 kg bag of sodium metabisulfite occupies about 19–23 liters. For a full container load of 20 metric tons, understanding the exact density allows logistics teams to plan container space, predict stacking loads, and calculate freight costs accurately. A higher settled density can mean more product per pallet, reducing the per-kilogram transportation expense.
In industrial water treatment or gold mining cyanide detoxification, sodium metabisulfite is dissolved into water to create a reducing agent solution. Operators frequently dose by weight, but if they must meter by volume, knowing the sodium metabisulfite density g/ml of the solid allows conversion from mass to volume for automatic feeding systems. This ensures the correct concentration of active SO2 is delivered to the process stream, avoiding under-dosing that compromises treatment or over-dosing that wastes chemicals and handling costs.
Density also influences flow properties. Sodium metabisulfite with consistent particle size distribution and adequate density flows freely from silos and big bags, minimizing bridging and rat-holing in hoppers. When sourcing, industrial buyers should request a certificate of analysis that not only confirms purity (97-98%) but also reports bulk density, as this relates directly to material handling performance.
To fully evaluate a chemical supplier, buyers must look beyond the price per ton. The following table compiles the essential physical and chemical data for sodium metabisulfite that appear on every professional specification sheet.
| Property | Value |
|---|---|
| Chemical formula | Na2S2O5 |
| CAS number | 7681-57-4 |
| Molecular weight | 190.1 g/mol |
| Appearance | White to yellowish crystalline powder |
| Odor | Slight sulfur dioxide odor |
| Density (solid) | 1.48 g/cm³ (1.48 g/ml) at 20 °C |
| Bulk density (loose) | 1.1–1.3 g/cm³ |
| Melting point | Decomposes above 150 °C |
| Solubility in water | 540 g/L at 20 °C |
| pH (5% solution) | 3.5–5.0 |
| Purity (commercial grade) | 97–98% min |
The molecular weight of sodium metabisulfite (190.1 g/mol) is a fundamental constant used in stoichiometric calculations. For example, in cyanide destruction at gold mines, one mole of sodium metabisulfite can theoretically neutralize two moles of cyanide when catalyzed by copper sulfate. Using the molecular weight, engineers calculate exact dosage rates: to treat 1 kg of free cyanide, approximately 3.66 kg of pure sodium metabisulfite is required. Any deviation in purity must be factored in, which is why a reliable, high-purity supply (97–98%) from a consistent source like our sodium metabisulfite product page reduces operational guesswork.
Industrial buyers often encounter both sodium bisulfite and sodium metabisulfite in the market. While they are chemically related and can be used interchangeably in many applications, their physical properties and handling characteristics differ significantly — and understanding these differences can lead to smarter sourcing decisions.
Sodium bisulfite (NaHSO3) is typically supplied as a liquid solution, whereas sodium metabisulfite is a dry powder. When dissolved in water, sodium metabisulfite quickly hydrolyzes to form sodium bisulfite, releasing sulfur dioxide in the process:
Na2S2O5 + H2O → 2 NaHSO3
This means solid sodium metabisulfite offers higher active SO2 content per unit weight – about 65% by weight – compared to commercial liquid bisulfite solutions that are often diluted to 20–40% concentration. For long-distance shipping or for operations in remote locations, purchasing dry sodium metabisulfite is far more economical. Buyers looking to buy sodium bisulfite in solid form actually need sodium metabisulfite, as true solid bisulfite is unstable. We encourage you to review the specifications and packaging options to see which product matches your logistics needs.
Beyond heavy industry, sodium metabisulfite also serves a critical biomedical role — in the sickling test used to diagnose sickle cell disease or trait. Laboratories rely on a freshly prepared reducing solution, and the preparation method directly affects test reliability. Knowing how to prepare sodium metabisulfite for sickling test ensures accurate results and avoids false negatives.
The most common protocol uses a 2% weight/volume sodium metabisulfite solution. To prepare:
In this application, the sodium metabisulfite density g/ml of the powder is irrelevant for mass-based measurement, but it is critical if a lab technician attempts to scoop by volume. A level teaspoon may yield anywhere from 4 to 6 grams depending on compaction, leading to concentration errors. Always use a calibrated balance. High-purity material (≥97%) is recommended to avoid interference from sulfates or thiosulfates that could affect the sickle cell deformation response. Industrial suppliers like Hailei Chemical can provide analytical-grade or food-grade material that meets laboratory requirements when a dedicated medical-grade product is not available.
Securing a reliable supply of sodium metabisulfite goes beyond meeting the minimum purity. The following factors, all tied to physical and chemical properties, should be on every buyer’s checklist.
Sodium metabisulfite is available in food grade (generally ≥98% purity, low heavy metals) and industrial/technical grade (≥97%). For food preservation and winemaking, food grade is non-negotiable. For water treatment and gold processing, industrial grade suffices but must have consistent assay values and minimal insoluble matter. Always request a certificate of analysis showing actual assay, iron content, and heavy metals.
As highlighted, sodium metabisulfite density and particle size distribution affect dissolution rate and handling. A supplier that double-crystallizes the product tends to produce a free-flowing, low-dusting powder with uniform density — a significant advantage in automated feeding systems. Verify that bulk density falls within the expected 1.1–1.3 g/cm³ range and that no caking occurs during transportation.
Exposure to moisture and air causes sodium metabisulfite to oxidize to sulfate, reducing its effectiveness. Top suppliers package the product in 25 kg polyethylene-lined bags or 1000 kg bulk bags with airtight sealing, sometimes under nitrogen. Ask about the packaging specifications and expected shelf life. Hailei Chemical’s sodium metabisulfite product specifications include detailed packaging information and storage recommendations.
Sodium metabisulfite is classified as a hazardous material (UN 3260, class 8) due to corrosive properties when wet. Knowledgeable suppliers provide msds, transport documentation, and assist with customs clearance for international shipments. Dimensional weight calculations for air freight or LCL sea freight depend on the container volume, which is directly tied to the product’s density. Confirming the exact sodium metabisulfite density g/ml from your supplier prevents costly miscalculations.
If your process allows use of a liquid reducing agent, you might also explore whether to buy sodium bisulfite solution locally to avoid dissolving solid powder on site. However, for high-volume operations where shipping water is inefficient, solid sodium metabisulfite remains the most cost-effective choice. Hailei Chemical offers both grades and can assist with a technical comparison to help you determine the best fit.
Sodium metabisulfite has a true density of 1.48 g/cm³, which is the same as 1.48 g/ml. This value represents the mass of the solid crystal per unit volume, without void spaces. The bulk density, which includes air gaps between granules, is lower — typically 1.1–1.3 g/cm³.
The molecular weight (190.1 g/mol) is used to convert between mass and moles in chemical reactions. For example, to determine how much sodium metabisulfite is needed to dechlorinate 1 kg of chlorine, you use the molar ratio and the molecular weight to find the required mass in grams.
Yes, in aqueous solutions they behave identically because sodium metabisulfite hydrolyzes to sodium bisulfite. Solid sodium metabisulfite is a convenient, stable source of bisulfite and is often the preferred form for industrial and laboratory use.
The 2% sodium metabisulfite solution should be prepared fresh daily. Its reducing power decreases over time, and using an oxidized solution may produce false-negative results in the sickling test.
Store in a cool, dry, well-ventilated area away from acids and oxidizers. Keep bags sealed and off the floor. If the product absorbs moisture, it can cake and clump, altering the bulk density and making handling difficult. Under proper conditions, shelf life is typically 12–24 months.
From the sodium metabisulfite density g/ml that dictates container utilization, to the molecular weight that anchors high-precision dosing calculations, the physical properties of this versatile chemical are far from trivial data points — they are the keys to cost savings, operational safety, and product performance. Whether you are sourcing for a mining operation in Africa, a municipal water plant in Southeast Asia, or a food processing facility, partnering with a supplier that understands these details makes all the difference.
At Weifang Hailei Fine Chemical Co., Ltd., we provide sodium metabisulfite in food grade and industrial grade with consistent purity and documented physical specifications. Our technical team is ready to answer your questions about density, packaging, or any other parameter relevant to your application.
Ready to secure a stable supply? Request a quote today and download our latest product datasheet. For detailed parameters, visit our sodium metabisulfite product page.