When sourcing potassium sulphate—also known as sulfate of potash (SOP)—for high‑value agriculture or precision industrial processes, one of the first technical parameters procurement specialists examine is potassium sulphate molecular weight. With a precisely defined value of 174.26 g/mol for the anhydrous K2SO4 molecule, this figure is far more than a chemistry textbook entry. It directly influences purity verification, stoichiometric calculations for batch formulations, and the predictable solubility behaviour that underpins everything from chloride‑free drip irrigation to pharmaceutical excipient quality. In this comprehensive guide, we explain why molecular weight matters, how it connects to the potassium sulfate chemical formula K2SO4, and what every B2B buyer should know about potassium sulfate solubility in water, real‑world performance, and reliable sourcing—drawing on decades of expertise from Weifang Hailei Fine Chemical Co., Ltd.
The potassium sulfate chemical formula K2SO4 tells a concrete story about composition. Each formula unit consists of two potassium cations (K+) and one sulfate anion (SO42‑). For procurement professionals, this simple notation unlocks a wealth of quality‑control data. Based on the standard atomic weights (K = 39.10, S = 32.07, O = 16.00), the theoretical molecular weight is 2(39.10) + 32.07 + 4(16.00) = 174.26 g/mol. Any deviation in an assay result from this figure suggests the presence of impurities—typically residual chlorides, sodium, or moisture. Because Hailei Chemical’s SOP is manufactured via the Mannheim process using pharmaceutical‑grade potassium chloride and sulfuric acid, our typical potassium sulphate molecular weight‑verified assay consistently delivers K2O content of 50% minimum by weight, with chloride levels below 0.5%. That purity makes it the premier choice for chlorine‑sensitive crops like tobacco, citrus, and avocados, as well as for the most demanding industrial applications.
Industrial users rely on the molecular weight to convert between mass and molar quantities. For example, a glass batch recipe requiring 0.5 mol of K2SO4 as a refining agent translates to exactly 87.13 grams of pure product. If the supplied material contains inert solids or free moisture, a simple stoichiometric calculation based on 174.26 g/mol becomes unreliable, potentially compromising furnace efficiency or glass clarity. Similarly, in pharmaceutical excipient formulation, the molecular weight is used to establish exact ionic contributions. Hailei Chemical attaches a Certificate of Analysis to every shipment, confirming the assay against the theoretical molecular weight—giving your quality team full confidence.
Beyond its molecular weight, potassium sulfate solubility in water is the most operationally critical physical property. K2SO4 dissolves endothermically, and its solubility shows a marked but manageable dependence on temperature.
| Temperature (°C) | Solubility (g K2SO4 / 100 g H2O) |
|---|---|
| 0 | 7.4 |
| 10 | 9.3 |
| 20 | 11.1 |
| 30 | 13.0 |
| 40 | 14.8 |
| 60 | 18.2 |
| 80 | 21.4 |
| 100 | 24.1 |
This moderate solubility, compared to highly soluble salts like potassium chloride, makes SOP especially suited for controlled‑release fertilizer blends and for applications where a steady, low‑concentration potassium source is desired—such as in foliar sprays or drip fertigation of premium greenhouse crops. It also explains SOP’s role as a refining agent in glass furnaces, where a precisely timed dissolution is needed to scavenge gaseous inclusions without creating refractory corrosion.
Buyers from aluminium recycling plants appreciate another facet: during the remelting of aluminium scrap, K2SO4 is used as a flux component to lower the melting point of oxide slag and improve metal recovery. The salt’s solubility curve guarantees that any residual flux on the recovered dross can be washed away with ambient‑temperature water, simplifying post‑treatment while keeping chloride‑induced corrosion out of the system. When you buy potassium sulfate from Hailei Chemical, you receive material ground to your specified particle size, ensuring dissolution kinetics align with your specific process window.
The overwhelming volume of SOP is consumed by agriculture, where its low chloride index is unmatched. Understanding the molecular weight is essential for fertilizer formulators to calculate the K2O equivalent. K2O has a molecular weight of 94.20 g/mol, and one mole of K2SO4 (174.26 g) yields one mole of K2O. The theoretical K2O percentage is therefore (94.20 ÷ 174.26) × 100 = 54.0%. Our commercial product guarantees a minimum of 50% K2O—a figure that accounts for small amounts of benign sulphate residuals and packaging‑related tolerances. Agricultural procurement teams use this conversion constantly when comparing SOP with potassium chloride (MOP) or potassium nitrate. Because SOP delivers both potassium and sulphur in the sulphate form, it simultaneously supports protein synthesis and enzyme activation without the osmotic stress that chloride can impose on sensitive root zones.
Agronomists calculate field application rates in kg K2O per hectare. With a guaranteed 50% K2O, a 100‑kg sack of Hailei SOP delivers 50 kg of K2O. A recommended rate of 200 kg K2O/ha for a high‑yield banana plantation therefore requires 400 kg of product per hectare. The same stoichiometric logic, rooted in the potassium sulphate molecular weight, empowers precise blending with monoammonium phosphate (MAP) and urea to create custom NPK grades without over‑ or under‑supplying sulphur. This calculability reduces over‑fertilisation risk and helps your downstream customers meet increasingly stringent environmental targets.
In the production of container glass, float glass, and specialty optical products, K2SO4 functions as a high‑temperature refining agent. Added in quantities typically ranging from 0.1 to 0.5 wt% of the batch, it decomposes above 1,100 °C, releasing sulphur dioxide that helps homogenise the melt and eliminate bubbles. The molecular weight is used by furnace operators to calculate the exact SO2 yield per kilogram of refining agent. Given that one mole of K2SO4 yields one mole of SO2 (64.06 g), a 1,000‑gram addition of pure SOP can theoretically release up to 367 grams of SO2. Predictability of this kind is invaluable when fine‑tuning a furnace that operates 24/7. Hailei Chemical supplies SOP in controlled granular and powder forms to ensure safe handling and consistent metering into the batch house.
Secondary aluminium smelters face the constant challenge of minimising metal loss to dross while avoiding chloride‑based fluxes that generate corrosive HCl fumes. Potassium sulphate provides a chloride‑free alternative that improves slag fluidity by lowering the liquidus temperature of the oxide skin. Its moderate solubility also helps in subsequent dross leaching steps, allowing valuable aluminium residues to be recovered without aggressive chemical treatments. When buyers seek to buy potassium aluminum sulfate—often confusing the two—they are typically looking for potash alum, which has a completely different chemistry (KAl(SO4)2·12H2O) and is used as a coagulant in water treatment, not as a slag conditioner. Understanding the chemical formula and molecular weight prevents such mis‑specifications and ensures you procure exactly what your process demands.
Pharmacopoeia‑grade potassium sulphate is used as an excipient in tablet formulations and as a component of mineral supplements. Here, the molecular weight is not a mere specification but a regulatory requirement. Monographs test for assay (typically 98.5–101.5% of theoretical K2SO4) and limit heavy metals, arsenic, and loss on drying. A product whose assay when tested against the 174.26 molecular weight falls outside this narrow window will be rejected. For pharmaceutical manufacturers, Hailei Chemical provides a dedicated low‑endotoxin grade screened through 200 mesh, supported by a full pharmacopoeial compliance dossier.
Procurement managers occasionally search for “alum potassium aluminum sulfate” when they actually need potassium sulphate. While both chemicals supply potassium ions, their applications diverge sharply. Alum (potassium aluminum sulfate) is a double sulphate salt with a molecular weight of 474.39 g/mol (dodecahydrate) and a strong astringent taste; it finds use in water purification, leather tanning, and as a mordant in textile dyeing. By contrast, our potassium sulfate chemical formula K2SO4 yields a neutral pH, low‑reactivity salt ideal for chloride‑free fertilisation and industrial fluxing. If your goal is to buy potassium aluminum sulfate, you will need a completely different specification sheet. This article focuses on potassium sulphate; for alum requirements, we recommend consulting a specialist supplier of aluminium salts.
The lesson is clear: always verify the chemical formula and molecular weight against your process requirement. When in doubt, request a sample and a certificate of analysis that quotes the assay relative to the theoretical molecular weight. Hailei Chemical welcomes such scrutiny and provides full technical documentation with every shipment.
Weifang Hailei Fine Chemical Co., Ltd. is one of China’s foremost manufacturers and exporters of premium potassium sulphate. Our production capacity exceeds 100,000 metric tonnes per year, backed by on‑site quality laboratories that verify potassium sulphate molecular weight conformity, particle size distribution, chloride content, and heavy metal levels in accordance with ISO 9001:2015 standards. We export to over 55 countries, servicing major fertiliser blenders, container‑glass multinationals, secondary aluminium smelters, and pharmaceutical grade distributors.
Every container of Hailei potassium sulfate is accompanied by a detailed COA, a safety data sheet, and, for agricultural grades, a product stewardship card outlining solubility and handling best practices. Our supply chain team can arrange packaging in 25 kg, 50 kg, or 1000 kg jumbo bags, with options for palletised and shrink‑wrapped shipping to prevent moisture ingress. For pharmaceutical clients, we provide aluminium‑foil‑lined fibre drums and dedicated lot traceability.
By anchoring your procurement decision on technical fundamentals—potassium sulphate molecular weight, the potassium sulfate chemical formula, and potassium sulfate solubility in water—you mitigate quality risk and unlock the full performance potential of this versatile inorganic salt. Whether you need SOP for a tobacco fertilizer programme, a float glass line, or a pharmaceutical excipient application, Hailei Chemical is ready to partner.
Take the next step: request a tailored quotation or download our latest specification sheet. Our technical sales engineers will respond within one business day to discuss your required chemical parameters, packaging preferences, and delivery timeline. Let’s transform your molecular‑weight knowledge into a reliable, cost‑effective supply chain.