What Is Calcium Hypochlorite?

Calcium hypochlorite takes the spotlight in many water treatment processes thanks to its strong oxidizing nature and solid content. Most people know it as a white or gray-white solid appearing just like tiny pellets, granules, or as coarse powder. Its chemical formula, Ca(OCl)₂, gives away its structure — calcium cations matched with two hypochlorite anions. This compound dissolves in water, setting off a reaction that releases hypochlorous acid, the real workhorse behind its role as a disinfectant. The earthy, almost metallic smell signals its potent chlorine content. With a molar mass of 142.98 g/mol, this salt carries a density in the range of 2.35 g/cm³, usually packed in tightly sealed containers because of its eagerness to break down in the presence of moisture. Each grain or flake packs a punch, usually carrying up to 70% available chlorine, which makes it much more concentrated than typical household bleach.

Products, Forms, and Specifications

Available in several forms, calcium hypochlorite meets different needs. Granules and powder versions serve best for pool sanitation and municipal water treatment, since their small size dissolves fast and hits target concentrations quickly. Pearls and pellets work well for slow, controlled release in smaller applications, while flakes often find their way into larger industrial uses. The product usually comes in sealed drums or pails, sometimes lined with protective plastic to guard against the material’s eagerness to absorb water from the air. Industrial-grade materials land between 65-70% minimum available chlorine, while lower grades suit household or small-scale use. Liquid solutions, although much less common due to instability, may be offered in diluted forms for ease of use. HS Code 282810 is attached for customs and international trade — a useful reference for importers and exporters alike. Raw state, bulk form, or custom packaging: what matters most is keeping the material dry and isolating it from any organic substances.

Molecular Structure, Formula, and Property Details

Diving into the molecular details, calcium hypochlorite shows a crystalline structure traced back to its ionic lattice. The calcium ion (Ca²⁺) sits bound to two hypochlorite groups (OCl^-), each consisting of a single oxygen atom connected to chlorine. The material keeps a relatively high melting point, only breaking down and releasing oxygen at temperatures nearing 100°C, then decomposing vigorously at higher temperatures. In solution, it interacts with water to form hypochlorous acid and calcium hydroxide, while the hypochlorous acid drives powerful germ-killing action.

Density, Solubility, and Stability

Calcium hypochlorite might not win any prizes for solubility, especially in cold water, but its slow dissolving rate makes it ideal for steady dosing in both pool and drinking water applications. Density measures sit just above most waterborne raw materials, which keeps it settled on the bottom when used in tanks or treatment units. Mildew, bacteria, and viruses stand no chance: the active chlorine works rapidly once water frees it from its solid state. The critical lesson I learned working in municipal plant operations: always add it slowly to water, not the other way around, since sudden reactions can lead to dangerous splashes or even rapid off-gassing. The material breaks down in sunlight or if stored in humid conditions, so it must be kept cool and dry.

Safety, Hazards, and Chemistry

Handling calcium hypochlorite asks for respect. The solid bears oxidizing properties—contact with grease, organic materials, or even clothing soaked in oil can kick off instant fires or explosions. Chlorine gas, highly toxic, may escape if mixed with acids or heated, leading to serious health consequences. Direct contact with skin or eyes causes burns and damage. Years of using it in swimming pools, I learned to always suit up with rubber gloves, goggles, and a dust mask. Never underestimate the value of good ventilation: even a small spill in a poorly-aired closet can leave your throat burning for hours if you’re unprepared. On the safety data sheet, it appears on lists as harmful and hazardous, flagged for both short and long-term health concerns. Proper labeling, sealed containers, and careful education of all staff—not just specialists—make all the difference between safe and risky operations.

Raw Materials and Production

The heart of calcium hypochlorite production centers on raw lime and chlorine gas. I once saw a production line up close; lime reacts with chlorine in controlled reactors, with heats of reaction carefully managed to avoid side products. The goal: yield a powder with consistent available chlorine, few impurities, and solid particle size that meets market demand. Stringent process controls, regular analysis, and robust safety measures define the state-of-the-art in production, whether in compact local plants or major international installations.

Environmental and Social Factors

Every year, thousands rely on calcium hypochlorite to guarantee safe water, clean pools, and sanitized surfaces. Still, concerns follow its widespread use. Chlorine’s reactive nature can create byproducts in water, some of which raise long-term health and environmental flags, including trihalomethanes. My experience managing a community water supply taught me that careful dosing and thorough filtration help cut down these risks, but the overall benefits for public health remain strong. Key solutions lie in smarter application technologies, advance monitoring of water systems, and clear communication with users about safe handling and proper storage.

Summary of Core Details

HS Code 282810, formula Ca(OCl)₂, density 2.35 g/cm³, available in flakes, solids, pearls, powder, liquid solutions, and crystals. Soluble in water with a slow rate, decomposes at high temperature. Powerful oxidizer, hazardous if mixed with acids or organic substances, causes burns and releases toxic gas if mishandled. Used across water treatment, sanitation, and industrial disinfecting, made from lime and chlorine gas, protected in sealed containers to prevent breakdown. Users benefit most from education on storage and handling, with growing attention on balancing cleanliness and health safety through measured application and up-to-date monitoring.