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Disodium hydrogen phosphate dihydrate, known in the lab as Na2HPO4·2H2O, started showing up in chemical texts in the mid-1800s, right when chemists began cataloging the various salts of phosphoric acid. Its use spread as industries, looking for reliable water softening and buffering agents, found that this salt did the job with stability and consistency. Dental and medical researchers leaned on these properties too, pushing its profile past the industrial sector and into healthcare. Folks working in agriculture soon caught on; they saw early on how it could support animal nutrition and soil correction. As our industries matured, manufacturers kept finding ways to up the purity and consistency, which made this material a mainstay in quality labs and food production.
Anyone who has handled water treatment chemicals or pH buffers will recognize disodium hydrogen phosphate dihydrate as a white, crystalline powder or sometimes as easily-handled granules. The pharmaceutical and food sectors appreciate its stability. Its role isn’t glamorous, but it’s essential, quietly maintaining the right environment for reactions or keeping foods shelf-stable and safe to consume. Big bulk shipments head to food processing plants, water utilities, and laboratories, since it carries food additive status and recognized safety, well documented by health authorities globally.
Disodium hydrogen phosphate dihydrate has a formula weight of about 177.99 g/mol. It dissolves well in cold and hot water, giving a basic solution thanks to the hydrogen phosphate ion. The melting point sits around 100°C, at which it effortlessly loses its crystal water, shifting to the anhydrous form. White, odorless, and non-hygroscopic, this compound looks and behaves like many common inorganic salts. In the cabinet, the powder stays caked and clumpy if the packaging lets in moisture, but otherwise, it stores with very little drama. Among the phosphate salts, it balances buffering power and solubility, making it a reliable bench staple.
Batch quality always counts, especially in regulated fields like the food and pharmaceutical trades. Producers standardize on minimum assay values, usually more than 98% pure, with strict limits on heavy metals, arsenic, and loss on drying. Labeling in these markets demands the official name, precise water content, batch number, date of production, and expiration date. Information sheets outline risks, storage procedures, and first-aid steps. If shipping across borders, handling standards and safety data reflect GHS conventions and local rules. For food use, the packaging always references registration numbers, reinforcing consumer safety guarantees.
Commercial production pulls from simple phosphate chemistry. Heated phosphoric acid meets sodium carbonate or sodium hydroxide—both affordable—producing sodium dihydrogen phosphate and then further reacting to reach the right hydrogen phosphate form. Dihydrate crystallization starts as producers cool concentrated solutions, where precise temperature controls let the crystals settle with just the right amount of water locked inside. These crystals are filtered, washed, and dried until the batch matches specs. The plants running this process watch for phosphate purity, as tweaks in mineral content or residual acid mean downstream complaints from buyers who need reliable, pure buffering agents.
Adding disodium hydrogen phosphate dihydrate to an acidic mixture nudges pH upward, as the compound mops up excess hydrogen ions. In water, it mixes with sodium dihydrogen phosphate to deliver a classic buffer pairing, keeping things steady around pH 7 to 9, which is the sweet spot for most food processing, lab techniques, and some medical formulas. Exposing it to strong acids pushes it down to monosodium phosphate; strong bases, and it heads to trisodium phosphate. These shifts matter because users can tune buffering capacity and pH range with just a little dosing change. It also sees use in precipitation reactions, where adding it to calcium salts lets chemists harvest fine, consistent calcium phosphate, a process that repeats in everything from toothpaste recipes to bioceramic production.
This salt travels with a full wardrobe of names. Trade registries call it Disodium phosphate, DSP, or Sodium phosphate dibasic. European suppliers use E339(ii) as a food additive code. Pharma supply catalogs stick to the chemical formalism, while cleaning supply chains may label it dibasic sodium phosphate. Cross-checking MSDS sheets and ingredient lists means learning the full list: Dinatriumhydrogenphosphat-2-Wasser (Germany), Phosphate de sodium (France), or just plain “buffer salt.” Consistent nomenclature matters because buyers and regulators recognize what they’re handling only through these strict names.
Disodium hydrogen phosphate dihydrate doesn’t create the kinds of splashy incidents that end up in the news, but any chemical in bulk brings risks. Inhalation of dust irritates the airways, and high ingestion levels upset digestion. Production floors must run dust controls, provide gloves and goggles, and give clear first-aid procedures. Food facilities stick to GMPs (Good Manufacturing Practices), logged and regularly audited. Operators learn to check lot codes and shelf life, since the salt quietly absorbs contaminants if mislabeled or poorly stored. Shipping by truck or container follows labels spelling out hazard classes, although this chemical travels without the drama of many hazardous materials.
Bakeries and cheese plants rely on disodium hydrogen phosphate dihydrate for buffering recipes and helping cheese emulsify evenly. Water utilities add it to control scale buildup, which keeps taps flowing and appliances running longer. Paints, textile dyeing, and cleaning products use it to keep reactions steady and solutions clear. Animal feed producers add it as a phosphorus and sodium source to boost livestock health, as decades of study show that misbalanced mineral profiles set back productivity. I’ve seen pharmaceutical labs adjust it into injections, giving drugs a pH that doesn’t sting. Medical device firms build it into dialysis solutions. Each field expects predictable behavior—no surprises, no off-flavors, nothing out of spec—which makes this boring but trusted phosphate essential for modern production.
Universities and R&D labs use disodium hydrogen phosphate dihydrate as a tool to study everything from protein folding to soil fertility. Drug formulators explore its buffering for new delivery vehicles and vaccine stabilizers. Enzyme and antibody work requires tightly controlled pH environments, where substitution with less familiar salts risks wrecking data sets. Researchers adapt production to meet new purity standards, especially as analytical instruments push the detection limits lower than ever before. Clean-label product developers ask whether natural-mined phosphates carry unique qualities, setting up new supply chains. Progress comes by refining methods, reevaluating risks, and substituting wherever alternatives offer more sustainable impact with the same reliability.
Scientists track safety through long-term ingestion, acute exposure, and environmental release studies. Decades of animal data and industrial exposure records indicate that disodium hydrogen phosphate dihydrate, at typical dietary and occupational levels, stays well within accepted safety margins. Regulatory bodies scrutinize its effect in sensitive populations, noting that rare kidney disorders or phosphate imbalances can cause issues with chronic high intake. Waterway studies focus on phosphate-driven algal blooms, encouraging tighter control of runoff and discharge. Modern safety calls center on the role this phosphate, and others, play in broader ecological cycles, urging output reduction and improved recovery practices where overuse might threaten local environments.
Disodium hydrogen phosphate dihydrate will not disappear from the world’s chemical toolkit. Trends point toward tightening purity, stricter environmental controls, and less waste in its industrial lifecycle. Demand continues in water treatment, processed foods, and healthcare, but growing pressure from environmental organizations pushes producers toward more transparency and greener processes. Research continues on recovery from waste streams and alternative phosphate sources. Automation and digital quality control systems let factories fine-tune processes, reducing batch variation and off-spec product. As agricultural, food, and pharmaceutical sectors adapt to new regulations and consumer expectations, this phosphate keeps doing the work that allows progress without fuss, securing its future not by innovation but by consistency and quiet service.
Disodium hydrogen phosphate dihydrate sounds complicated. Most folks just call it a food additive or laboratory salt, but it pops up in a lot of everyday places. In the kitchen, it acts as a stabilizer in powdered foods. Baking powders, processed cheese, and even coffee creamers often rely on steady ingredients like this to keep from clumping or going bad too soon. Sure, those cheese slices melt just right because something in there helps balance the acidity, keeps the flavor sharp, and prevents separation. That something often comes from chemicals with long names, like this one.
People care about what chemicals do to food. Nobody wants extra sodium or additives without reason. Companies use disodium hydrogen phosphate dihydrate for good reasons, though — it manages pH, supports even textures, and keeps things safer for longer. The FDA has cleared it for use in food, so it isn’t just thrown in without testing.
Some worry about extra sodium, and that’s fair. High sodium, especially too often, raises blood pressure and isn’t good for the heart. The thing is, this compound adds less sodium than table salt. Still, folks with health issues or hypertension often read labels carefully and limit processed foods altogether. That’s where nutrition education helps more than lists of ingredients nobody understands. People should ask questions about anything they eat. Food manufacturers and health professionals can share more about why additives are used — and why moderation matters for everything, including this type of salt.
Step away from the dinner table, and this compound finds a place in science labs. It’s not just some mysterious white powder on shelves. In my university days, I mixed up buffer solutions for biology experiments, and disodium hydrogen phosphate dihydrate helped maintain the right chemical balance so cells didn’t die too quickly during study. Chemistry labs rely on it to control pH, especially in reactions that react badly to sudden acid or alkaline changes. Workers handling water treatment throw this chemical into mixes because it traps heavy metals and softens water. Without that simple step, pipes might corrode faster, or the water supply could fail tests for safety.
People get uneasy about long, chemical names. The debate about additives is bigger than one compound. I’ve taught enough high school science to know that students care about what’s in their snacks and drinks. I’ve seen smart policy in schools where teachers explain why processed foods use certain stabilizers or emulsifiers, using real-life demonstrations instead of dry lectures. More transparency would help everyone — parents, patients, and consumers — understand the “why” behind these additives instead of feeling left in the dark.
It isn’t about banning every hard-to-pronounce ingredient, but about making better choices. Eating mostly fresh or less-processed foods, reading nutrition labels, and asking questions makes more of a difference than just removing one compound. Food makers can help by offering clear information and limiting additives where possible. Science teachers, dietitians, and medical staff can all play a part by giving real answers without scare tactics.
Disodium hydrogen phosphate dihydrate isn’t dangerous when used responsibly. It does its job in food, science, and industry. We all have a responsibility — companies, teachers, parents, consumers — to keep learning, asking, and adapting. Safe food, honest science, and informed choices all benefit from some straight talk and an eye on both the kitchen and the chemistry lab.
Disodium hydrogen phosphate dihydrate carries the chemical formula Na2HPO4·2H2O. Breaking that down, you see two sodium ions, one hydrogen, one phosphorus, and four oxygens for the main phosphate group, plus two water molecules. These two hydrates might sound like a fine detail, but in practical use, those water molecules aren't just along for the ride. They impact everything from shelf life to how the solid dissolves in water.
Having spent part of my career in a lab, I learned early on that grabbing a bottle of the wrong hydrate can change the outcome of your work. Looking at a white crystalline powder, you wouldn’t know how many water molecules are tucked inside unless you read the label. In titrations, chemical syntheses, or buffer preparation, missing those two waters can throw off measurements. A 2017 study out of Purdue University highlighted mistakes in solution prep linked to confusion between different hydrates of sodium phosphate. This cuts into accuracy, wastes resources, and can get scientists running in circles trying to fix oddball results.
Water content in a compound shifts its molar mass. If the label says “dihydrate” but someone calculates for the anhydrous version, every molarity calculation for solutions heads off track. Pharmaceutical labs, food industry technicians, and wastewater treatment plants keep an eye out for these specifics. Missteps mean spoiled batches, failed quality tests, or, in food and water processing, outright regulatory violations.
A lot of the confusion comes from similar names and lazy storage practices. Back in my grad school days, more than a few folks—myself included—learned the hard way after using anhydrous sodium phosphate instead of the dihydrate, sending carefully measured pH values far from target. The margins for error don’t leave much room for assumption. Labeling habits, and how well stockrooms track batches, matter as much as chemical expertise.
The best defense against hydrate headaches comes from clear procedures and regular training. Double-checking chemical labels every time and keeping stocks organized by hydrate type reduce mix-ups. Weight calculations should always start with the right formula—see “Na2HPO4·2H2O”—not just what’s familiar from memory. In my own work, these habits cut down on wasted hours. Using standardized labels and updating inventory systems whenever new chemicals arrive also help keep everyone honest and informed.
Disodium hydrogen phosphate dihydrate plays an unseen yet vital role in countless applications, from baking to water purification. Those two water molecules change both math in the lab and results in the field. Giving attention to basic chemical formulas, checking sources, and fostering a culture of precision make a world of difference. Whether troubleshooting a buffed pH in a buffer or working out stoichiometry for a reaction, starting with the right formula counts as much as any sophisticated equipment.
Open up the label on a box of cookies or a packet of instant mashed potatoes and long, scientific names often jump out. Disodium hydrogen phosphate dihydrate sounds like something out of chemistry class. At its core, it’s a salt commonly used as an emulsifier, acidity regulator, and stabilizer. Many foods we grab on busy weekdays, especially those labeled as processed or convenient, blend in these sorts of additives.
This compound balances acidity, keeps powdered foods from clumping, and helps cheeses melt smoothly. Instant pudding owes its texture to ingredients like this, and powdered soups dissolve with fewer lumps. Behind these simple results lies a basic truth: widespread use always invites questions about safety.
Food safety agencies look closely at ingredients before they land in your favorite products. Disodium hydrogen phosphate dihydrate has turned up in research for decades. Studies from the European Food Safety Authority and the United States Food and Drug Administration both consider it “generally recognized as safe” at the levels used in foods. The World Health Organization points in the same direction, having set growth and health standards that guided its accepted daily intake.
The reason for these reassuring findings sits in basic biology. Our bodies already contain and process phosphate compounds. Foods like meat, fish, and dairy contribute natural phosphates every day. On its own, this compound doesn’t work much differently than the phosphates found in whole foods. Most of what you eat gets absorbed, filtered through the kidneys, and then excreted. Unless someone has kidney problems or a rare phosphate metabolism issue, the body manages these salts well.
That doesn’t mean every food additive’s story is the same for everyone. Chronic kidney disease, for example, changes how people handle phosphate. An extra jolt from food additives can tip the balance for those individuals, with possible effects on bone and cardiovascular health. Some research points to high long-term phosphate intake linking to health problems, but it often involves much higher amounts than anyone eating a typical diet would see.
For anyone worried about additives, the practical move starts in the grocery aisle. Check labels, and build meals around whole foods. Choosing unprocessed grains, vegetables, and legumes almost always means less exposure to engineered ingredients. Nutritionists keep pushing for this pattern not just because of additives, but since these foods bring vitamins, fiber, and antioxidants, too.
Nobody wants every meal to become an experiment in chemistry. There’s reassurance in the fact that regulatory bodies revisit the science on food additives year after year. Still, food culture shapes habits, and it’s easy to drift toward convenience. Growing up surrounded by home-cooked staples and seeing my family lean on real ingredients taught me a simple lesson: moderation pays off. No single food additive stands out as a villain when diets stay broad and balanced. Sensible eating and informed label reading give everyone a fair shot at both convenience and health.
Disodium hydrogen phosphate dihydrate shows up in labs, classrooms, and sometimes even in food processing. Most people recognize its powdery form, but not everyone pays attention to what improper storage can do to it. I’ve seen good chemicals go to waste not because of poor quality, but because no one followed simple rules to keep them safe from air, moisture, or contamination.
Strength and reliability depend on keeping chemistry supplies in their best condition. This chemical draws moisture out of the air, so if someone leaves the lid off, caking and degradation start almost immediately. In one busy college lab, I watched a teammate ruin an entire bottle by storing it near a sink—steam and splashes turned it solid and unusable in weeks.
Place the container somewhere cool and dry. Warm, humid rooms speed up the absorption of water and can turn fine powders into rock-hard lumps. Even storing it on a window ledge, where the sun heats the air and raises humidity, can break down the product’s integrity. According to standard laboratory practice, aim for conditions below 25°C and humidity under 60%. Once, during a summer heat wave, I saw bottles left too close to radiators; they ended up packed like clay, losing their usefulness in any precise application.
A tightly sealed original container offers the best defense against air and contamination. If transferring to a new bottle becomes necessary, use a clean, dry, airtight option—never glass jars with loose lids or open-top beakers covered only with foil. Plastic containers with proven chemical resistance provide a safer choice for daily access.
Make sure the cap or lid clicks or screws on completely after each use. Avoid scooping out powders with wet utensils, as even a trace of water can start the chemical’s degradation inside the jar. The difference in quality is visible over time: a dry, airtight jar keeps powder loose, white, and reliable, while poor sealing leaves a block of unusable material.
Keep chemicals away from strong bases, acids, and volatile substances. This phosphate absorbs odors and vapors from nearby bottles, changing its quality and impacting whatever recipe or formula comes next. I remember a storage shelf in a teaching lab where chemicals shared space without separation. The result? Cross-contaminated powders that leaked unfamiliar smells and ruined experimental reliability.
Even accidental mix-ups due to poor labeling and open bottles hurt both scientific results and safety. Always label each bottle with the contents, date received, and any hazard symbols. This might sound basic, but too many chemicals end up in trash bins because someone forgot to check a faded marker label.
Years handling laboratory chemicals taught me that small steps prevent costly mistakes. Using a secure storage cupboard with climate control, keeping containers closed, and using clean, dry tools adds up to better results, lower waste, and a safer environment. Colleagues once ignored these habits and spent hours chiseling out powder, only to discover it had lost potency. Storing properly turns a bag of raw material into a dependable resource every time.
Following good storage practices boosts reliability, cuts down on loss, and gives peace of mind when reaching for that next pinch or scoop.
Disodium hydrogen phosphate doesn’t usually make headlines, but it touches more lives than most people realize. Found inside labs, in food processing, and sprinkled into products for its stabilizing touch, this chemical keeps things running smoothly. Here’s the thing a lot of first-year chemistry students learn the hard way: the water built into this compound makes a difference. Dihydrate means the chemical holds two water molecules per formula, while the anhydrous version is dry and stripped down. You might shrug this off, but those waters control how this stuff dissolves, how much bulk it takes up in the package, and how stable it stays over time.
I’ve worked enough in both food plants and university labs to see the practical side. In a bakery, the dihydrate form looks a bit clumpy, almost soft to the touch. The anhydrous version, on the other hand, pours more like common salt. The real surprise comes from weighing them. For the same chemical punch, you’ll need a heavier scoop of dihydrate, since a chunk of its weight is just water. A lot of production mix-ups come from skipping this detail. I once saw a batch of cheese sauce turn out thin and salty—someone swapped in the anhydrous powder without adjusting the weight. That sort of mistake costs money, time, and a little dignity.
In water, dihydrate crystals melt in faster. They give up their grip on the water pretty willingly because they're already holding some inside. The anhydrous version can be slower to dissolve, and in some tightly monitored procedures, that causes headaches. I’ve noticed this most during prep work for buffer solutions, where getting to the right pH fast is crucial. If you don’t adjust for the type, you can overshoot the mark or spend precious minutes watching grains at the bottom of your flask.
Chemically, the extra water in dihydrate means it’s a little less concentrated. Comparing weights, 178 grams of dihydrate carries the same amount of the phosphate ion found in 142 grams of its anhydrous cousin. Food standards and pharmaceutical manuals spell this out, but I’ve watched new hires miss it again and again. The U.S. Pharmacopeia lists both, and it expects manufacturers to know which is which. This separates amateur operations from the reliable ones.
In humid climates, anhydrous powders draw in water from the air, sometimes turning into the dihydrate form over days or weeks. That shift matters in pharmaceuticals, where dose and stability aren’t negotiable. More than one warehouse manager has noticed those caked-up clumps in the bottom of old sacks and had to toss product past its best.
A little training prevents headaches. Any facility using both forms should label bins in bold, note conversion weights on recipe cards, and double-check with spot tests. Even for home experiments or culinary uses, looking at the fine print keeps recipes from going sideways. In my experience, talking these points through at onboarding goes farther than an email full of numbers. Companies can also use QR codes linking recipe sheets to videos that walk through the differences in plain language.
Mixing up dihydrate and anhydrous forms is a classic rookie move. Anyone accountable for food safety, lab precision, or medical quality needs clean handling practices and checks in place. Knowing the difference saves money and embarrassment, and it reinforces trust in whatever you’re selling or studying.
| Names | |
| Preferred IUPAC name | Disodium hydrogen phosphate dihydrate |
| Other names |
Disodium Phosphate Dihydrate Disodium Hydrogenorthophosphate Dihydrate Disodium Phosphate Dibasic Dihydrate Sodium Phosphate Dibasic Dihydrate DSP Dihydrate |
| Pronunciation | /daɪˈsəʊdiəm ˈhaɪdrədʒən ˈfɒsfeɪt daɪˈhaɪdreɪt/ |
| Identifiers | |
| CAS Number | 10028-24-7 |
| Beilstein Reference | 172205 |
| ChEBI | CHEBI:61389 |
| ChEMBL | CHEMBL1200803 |
| ChemSpider | 23440 |
| DrugBank | DB09449 |
| ECHA InfoCard | 03d72ab8-f0b5-41be-b8af-57a2930c3b51 |
| EC Number | 01-2119489797-11-XXXX |
| Gmelin Reference | 81463 |
| KEGG | C08357 |
| MeSH | Dibasic Phosphates |
| PubChem CID | 61390 |
| RTECS number | WC4500000 |
| UNII | 31C49V3JU9 |
| UN number | Not regulated |
| CompTox Dashboard (EPA) | DTXSID8036256 |
| Properties | |
| Chemical formula | Na2HPO4·2H2O |
| Molar mass | 177.99 g/mol |
| Appearance | White crystalline powder |
| Odor | Odorless |
| Density | 1.52 g/cm³ |
| Solubility in water | Easily soluble in water |
| log P | -4.1 |
| Acidity (pKa) | 12.32 |
| Basicity (pKb) | 12.38 |
| Magnetic susceptibility (χ) | -62.0e-6 cm³/mol |
| Refractive index (nD) | 1.412 |
| Dipole moment | 6.0 D |
| Thermochemistry | |
| Std molar entropy (S⦵298) | 191.0 J·mol⁻¹·K⁻¹ |
| Std enthalpy of formation (ΔfH⦵298) | −1712.0 kJ/mol |
| Std enthalpy of combustion (ΔcH⦵298) | -2855.4 kJ/mol |
| Pharmacology | |
| ATC code | B05XA03 |
| Hazards | |
| Main hazards | Not a hazardous substance or mixture. |
| GHS labelling | GHS05, GHS07 |
| Pictograms | GHS07 |
| Signal word | No signal word |
| Hazard statements | H319: Causes serious eye irritation. |
| Precautionary statements | P264, P270, P305+P351+P338, P301+P312, P330 |
| NFPA 704 (fire diamond) | 1-0-0 |
| Lethal dose or concentration | LD50 Oral Rat 17,000 mg/kg |
| LD50 (median dose) | > 17,000 mg/kg (rat, oral) |
| NIOSH | NC0054520 |
| PEL (Permissible) | Not established |
| REL (Recommended) | 6 mg/m³ |
| Related compounds | |
| Related compounds |
Disodium Hydrogen Phosphate Sodium Phosphate Monosodium Phosphate Trisodium Phosphate Sodium Dihydrogen Phosphate |
