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Hydrogen chloride, recognized today as hydrochloric acid in its aqueous form, has a colorful past stretching back centuries. Alchemists in the Middle Ages uncovered it by mixing common salt with sulfuric acid, long before industry took notice. Early records from the 16th century reveal experimenters hunting for new acids and stumbling across this sharp, volatile compound. Industrial revolution brought enthusiasm for substances that could break down minerals and boost textile processing. Chemical giants—many of them still around—scaled up production using practical, brute-force methods. In my early lab work, handling hydrochloric acid felt like participating in a tradition that’s shaped metallurgy, dyeing, and ore refining for generations. Records from the 1800s, notably those chronicling Leblanc’s soda process, reveal how hydrochloric acid became less a laboratory curiosity and more a commercial workhorse.
Known simply as HCl in the chemical world, hydrogen chloride takes on a distinct character as a pungent, colorless gas or, more commonly, as a watery, highly corrosive liquid. In concentrated form, hydrochloric acid breathes fumes, a detail no one forgets after their first encounter in a chemistry lab or industrial facility. You’ll see it on shelves in concentrations from 10% to 38%, each labeled with care for intended application—pickling steel, adjusting water pH, or etching semiconductors. Science education always highlights its unique role as a strong acid, one almost entirely dissociated in water, promising powerful reactions and utility across many fields. Manufacturers package it both in small glass containers for research and drums or tankers for bulk users, mindful of strict labeling rules shaped by both local and international standards.
Hydrogen chloride, in its pure gaseous state, remains colorless but sharply irritating in confined spaces. It’s got a density just heavier than air, about 1.53 grams per liter, and there’s no ignoring the way it draws water from anything it touches, including human tissue. Dissolved in water, it ramps up electrical conductivity, drops the pH close to zero, and reacts with everything from metals to bases. In the field, you measure its concentration by titration—an approach as old as modern chemistry. Its boiling point—about minus 85°C as a pure gas—rarely matters in everyday handling, but the volatility does mean decent ventilation tops the list of precautions in any worksite or classroom. Hydrogen chloride attacks metals like iron, zinc, and magnesium, liberating hydrogen and forming chlorides, a reaction every student has demonstrated at the bench with a strip of scrap metal and a dropper bottle.
Quality and safety intersect in the specifications for hydrochloric acid. Chemists look for clarity, lack of organic contamination, and precise concentration, often expressed as “percent by weight” or “normality.” Labels carry clear warnings: “corrosive,” “keep away from incompatible materials,” and statements about required personal protective equipment. Transporting hydrogen chloride or hydrochloric acid means checking for UN numbers and hazard diamonds—water-reactive in some contexts, always aggressive toward skin, eyes, and respiratory passages. In my own experience, strong labeling doesn’t just meet regulations; it drives home the point for newcomers that this chemical, for all its uses, demands respect and focus.
Production takes two principal paths: direct synthesis from hydrogen and chlorine, or by releasing hydrogen chloride gas from the reaction of sodium chloride with sulfuric acid. Industrial-scale operations burn hydrogen in a stream of chlorine under tightly controlled conditions, cooling the gas and dissolving it in chilled water to create bulk hydrochloric acid. In high school labs, students might recall the dramatic fizzing that comes from dropping salt into sulfuric acid, an echo of older production methods. The choice depends on scale and need—direct synthesis dominates for sheer volume, while smaller-scale operations may still lean on the traditional approach for specialty runs. All of it hinges on careful monitoring: uncontrolled reactions risk producing dangerous chlorine gas, underlining that industrial chemistry walks a fine line between productivity and hazard.
Reacting hydrochloric acid with metals yields metal chlorides and hydrogen gas—key steps in extracting valuable metals or recycling spent materials. Hydrogen chloride in the gas phase, passed over activated carbon, can strip out impurities or modify surfaces for further reactivity. It combines with ammonia to give ammonium chloride, and with carbonates to produce carbon dioxide. Chemists leverage these reactions to tweak or refine everything from food ingredients to pharmaceuticals. In the dyes and pigments sector, hydrochloric acid adjusts color and solubility, while water treatment operators rely on it to neutralize alkaline streams or regenerate ion exchange columns. I've watched technicians fine-tune acid strength, blending weaker solutions from fully concentrated stock to avoid material degradation in sensitive processing equipment.
Hydrogen chloride hides behind a patchwork of names, both formal and informal: muriatic acid around hardware shops, spirits of salt in older texts, and E507 as a food additive. Label differences stem from tradition and marketplace, but chemical purity sits at the heart of legal distinctions. Hardware stores often sell less refined acid for pool and masonry use, while laboratories and healthcare providers demand higher grades for analytical or pharmaceutical work. International shipping catalogs show hydrogen chloride packaged under various trade names, but the risks and rules do not shift with the label—a hazard under any brand, always managed with the same consistent oversight.
No one working with hydrochloric acid ignores the threat it poses. Strong acid has a way of impressing its presence on the senses, with biting fumes and the stark, rapid corrosion of metals or skin. Modern facilities drill safety rules into every staff member, focusing on full-face shields, chemical-resistant gloves, and splash-proof aprons. Workplace standards limit exposure to a few parts per million in the air, and engineers add scrubbers or local exhaust to keep levels low. In cleanup, spill kits include neutralizers like sodium bicarbonate, and emergency eyewash stations must never run dry. I’ve seen firsthand how a single lapse—in storage, in labeling, or in handling—can trigger not just injury but a full halt to operations while hazards are controlled and mitigated. The seriousness of these procedures springs from real incidents, somewhere in almost every company’s institutional memory.
The spectrum of hydrochloric acid usage reflects its versatility. The steel industry counts on it for pickling—clearing rust and mill scale before further processing. Water treatment plants rely on it to adjust pH and regenerate filters, keeping municipal supplies in line with health regulations. Food processing needs high-purity acid to produce gelatin, process sugar, and stabilize starch. Elsewhere, electronics manufacture calls for ultrapure hydrochloric acid to etch semiconductors and clean silicon wafers, a world apart from the pool supply aisle but no less reliant on the same basic molecule. Homeowners use diluted forms for cleaning masonry or balancing swimming pool water, often with little sense of the substance’s historic and global reach. A few drops in a beaker or tons stored outside a refinery—both pull from the same well of chemistry.
Research into hydrogen chloride isn’t static, even after centuries of use. Industry teams and university labs push for process efficiency, safer handling, and applications in green chemistry. Work continues on minimizing emissions during large-scale synthesis and recycling spent acid from metal finishing and catalyst regeneration. In my own projects, tracking impurities in hydrochloric acid helps safeguard product quality, especially in sensitive pharmaceutical or electronics applications. Scientists keep seeking better containment materials to limit leaks and extend equipment life, and the search for less corrosive alternatives in certain settings pushes innovation on all sides. Newer uses pop up in unexpected places, like bioplastics manufacturing or advanced energy storage. Each change builds on what’s come before, revised as tools, standards, and expectations evolve.
Toxicologists and medical professionals have studied hydrochloric acid’s hazards for generations. It’s corrosive to skin and mucous membranes, with inhalation sometimes leading to bronchospasm or chronic respiratory issues for unprotected workers. Long-term studies track cancer risk and tissue damage, updating workplace standards and treatment protocols to reflect new findings. First aid responders drill procedures for acid exposure, knowing that rapid decontamination makes the difference between minor injury and lasting harm. Regulatory agencies oversee everything from allowable air levels to required medical monitoring, basing their decisions on rigorous evidence and case reviews. I’ve heard veteran safety officers tell stories that remind everyone—young workers and seasoned pros alike—that chemicals like hydrochloric acid deserve the same care day in and day out.
Looking ahead, demand for hydrochloric acid tracks with global manufacturing growth, especially in steel, water treatment, and advanced materials. Environmental pressures push producers to recover and recycle more acid, install emissions controls, and reduce the health burden on workers and communities alike. New applications beckon, from refining battery materials for a low-carbon future to purifying inputs for semiconductors powering the next wave of consumer electronics. Researchers keep probing into less hazardous alternatives for niche applications, but the raw utility and adaptability of hydrogen chloride make it a fixture in laboratories and industries worldwide. Those involved—chemists, engineers, regulators, and everyday users—shape the story as needs change, reminding us how deeply one chemical can shape the world when managed with skill and respect.
Most folks either get a faint whiff of chlorinated swimming pools or picture the classic high school chemistry experiment when they hear “hydrochloric acid.” The truth goes beyond what most people expect. Hydrogen chloride, in its solution form as hydrochloric acid, quietly keeps daily life running in ways that usually escape notice. This strong acid doesn’t just belong in a beaker or as an intimidating bottle in the janitor’s closet.
Growing up in a Midwest town dotted with steel mills, I saw how hydrocholoric acid plays a big hand in preparing steel for use. Mills use “pickling” baths, where newly rolled steel dips into hydrochloric acid to strip away rust and oxide so the metal doesn’t fall apart early. Rust removal can’t be just about looks – it keeps bridges sturdy, machines humming, and cars safer. This step isn’t some optional extra; scrap metal yards and refineries depend on it, both for quality and lifespan.
Walk into most janitorial supply rooms and there will be hydrochloric acid-based cleaners. Tile and grout regain their shine, limescale and tough stains get lifted in bathrooms and kitchens. This acid breaks down mineral deposits in toilet bowls and pipes, keeping water flowing and plumbing bills down. As a former custodian, I remember the fumes more than once, but also noticed that not much stands up to hydrochloric acid’s cleaning power.
Food companies use regulated amounts of hydrochloric acid to tweak acidity, especially when making products like gelatin, high fructose corn syrup, or when adjusting the pH in foods to keep bacteria at bay. Some people don’t realize that FDA guidelines strictly control these uses to make sure products stay safe for consumers. Without it, large batches of processed foods could spoil quickly, leading to massive amounts of waste and foodborne illness.
Many plastics start with chemical reactions made possible by hydrochloric acid. PVC—the plastic used for everything from water pipes to credit cards—relies on this acid during its manufacturing process. Pharmaceutical companies use it when producing medicines, either for synthesizing key ingredients or balancing pH in final products.
A good water treatment plant monitors and corrects pH to prevent pipes from corroding and to comply with health regulations. Hydrochloric acid lets operators adjust water to safe pH levels, protecting not only the infrastructure but also the people at the end of the tap. Without proper pH adjustments, water can leach metals like lead from old pipes.
Hydrogen chloride is strong stuff, and improper use can cause burns, release dangerous fumes, or damage the environment. Workers need gloves, goggles, and well-ventilated spaces. Community awareness and workplace training need to remain high, since accidents can lead to evacuations or worse. Regulators and employers share a responsibility to educate and monitor safe handling to avoid tragedy.
Some groups focus on greener substitutes and tighter recycling in industrial processes to limit environmental impact. Innovations in containment, spill response training, and digital monitoring might also help reduce risks over time. Each step forward helps balance safety and practicality, keeping this powerful tool working for people, not against them.
Experience in the lab taught me quickly: hydrogen chloride, or hydrochloric acid in its watery form, demands respect. One accident—an errant drop on my glove—told me how fast it stings the skin. The stuff cuts through flesh and destroys metal, not because it’s rare or mysterious, but because many people underestimate it. School chemistry classes mention its dangers, yet stories keep surfacing about burns and breathing problems simply because someone skipped a mask or thought goggles were optional. Facts speak plain: concentrated hydrochloric acid can chew through clothing, and its fumes can make breathing painful after a few minutes.
My own rule holds: if you work with hydrochloric acid, you suit up before touching the bottle. Gloves—those made from nitrile or neoprene, not bare cotton—give your hands a fighting chance. Splash goggles do more than keep fog and dust out; they keep that sharp smoke away from your eyes. A face shield makes sense for any pouring job. Aprons crafted from rubber can shrug off accidental splashes. From real experience, walking across the hallway to grab the right gear always feels better than fumbling with a first aid kit later.
Anyone who’s opened a bottle of hydrochloric acid in a closed room knows the spicy bite that fills the air. It reaches your throat fast. The acid’s fumes are heavier than air and gather low, so simply opening a window almost never does enough. Labs use chemical fume hoods for a reason. In high school, our spray booth saved more than one clumsy experiment from turning into a health problem. Moving acids around only in well-ventilated places can keep those fumes out of your lungs and keep accidents from hurting more than fingers.
Long-term storage of hydrochloric acid needs sturdy plastic containers, not metal cans. Shelving holds up better when it stays dry and out of sunlight. Even the labels matter. Nobody benefits from grabbing the wrong container or knocking over a half-opened bottle. I’ve seen acids stored too close to bases, leading to bad reactions that scared everyone involved. Keeping hydrochloric acid far from things like bleach keeps things safer.
Small spills should go on baking soda or spill-neutralizer granules, not a mop. All the paperwork, all the safety data sheets (SDS), serve a purpose here. Sweat and nerves can get in the way, but knowing what to do comes from reading those sheets before anything spills. For larger leaks, leave and call in professionals: no amount of do-it-yourself fixes can match proper emergency response teams.
Factories, labs, even home experimenters game the system if they skip the basics. Clear rules, refresher training, and knowing how to use an emergency shower make a difference. That’s what turned nervous beginners into cautious workers during my time teaching science workshops. More injuries happen when shortcuts look easier than they are. Confidence grows from knowing you’re prepared. Sometimes the right equipment is sitting on a dusty shelf, but the real safety comes from using it every time.
Concentration matters—chemicals and ingredients don’t operate on guesswork. Different jobs call for different strengths, and mistakes get expensive fast. Most suppliers sort out their offering by putting out multiple concentrations. A standard example is hydrogen peroxide: you’ll spot 3% bottles on the shelves at supermarkets, used for cleaning wounds at home. In a school lab or industrial plant, 30%, 35%, or even stronger forms show up. Farmers, brewers, and cleaners don't use the same stuff as hospitals or DIYers. Catering to this variety keeps people safe and businesses compliant.
Bottle, drum, tote, or bag—what something comes in shapes how you handle it. Small glass vials or dropper bottles get popular in research labs. They help measure exact quantities and keep things tidy. Gallon jugs and five-liter cans will do for bigger jobs like janitorial supply closets or farm sheds. Drum and tote deliveries become the backbone for factories and commercial jobs where bulk matters way more than convenience.
In my own days working on a biotech project, nothing slowed us down like waiting for the correct container size. Our bench science needed tiny, well-sealed ampoules to keep things clean and avoid waste. Ordering a big drum when we had no ventilated cabinets, no proper pumps—people end up improvising with unsafe workarounds. Bad choice.
Safety isn’t some abstract requirement—proper packaging makes a real difference. Chemicals break down from light, air, or careless handling. Suppliers often choose opaque, tough plastics or glass to shield what’s inside. Acids and concentrated bases, for example, often ship in high-grade polyethylene. Sensitive oils or vitamins get amber-colored bottles to block sunlight. Leaks are rare if you buy from reputable sources, but they can turn bad quickly if corners are cut.
A small manufacturing business may find value in 10-kilogram sacks or 20-liter buckets, while a family-owned bakery shops smaller. This matters not just for convenience; there’s a costs and logistics edge too. A bakery overwhelmed with 200-liter drums won’t cut costs if half the product spoils or storage becomes awkward and unsafe.
Understanding the units—grams, milliliters, liters, kilograms—helps compare prices and avoid surprise. One liter is a thousand milliliters, but a price that sounds high for a 50-milliliter vial might be a bargain when stretched out by the job at hand. Nobody likes a last-minute run for more supplies or, worse, sitting on an expensive stockpile that’s past its best.
People with experience will confirm that tightfit packaging can save money by reducing waste and spill risk. Local governments and green-minded businesses push for returnable or recyclable containers. Some industries keep plastic out of the landfill by sending drums back for refills, or using single-dose packets when measuring errors get risky—like hospitals.
Not everyone has access to the perfect packaging. Outlying regions or cash-strapped organizations sometimes get stuck with “what’s available” instead of “what’s ideal.” Flexibility from suppliers, plus clear guidance on storage and disposal, has a real impact here. The products last longer, stay safer, and keep the people who use them out of the hospital.
Making the right choice comes down to honesty about usage, risks, and workflow. Businesses that educate staff on both product concentration and container style skip a lot of the mishaps, wasted money, and legal trouble. Transparency from suppliers and customer feedback makes a difference. When everyone in the chain—from manufacturer to end user—respects these details, the product does its job without surprises.
Hydrochloric acid, sometimes called hydrogen chloride in solution, shapes many industries from cleaning to food production. If you see a bottle labeled with fumes and a biting smell, you know you’re dealing with a substance that commands respect. I’ve worked near plants that handled hydrochloric acid—mistakes didn’t just mean a ruined workday, but sometimes a trip to the hospital. Skin contact leads to burns, inhaling the vapor damages lungs, and leaks can corrode steel or turn the soil beneath a tank into a hazardous zone. Safety goes far past wearing gloves or goggles; it means thoughtful decisions about where, how, and with what equipment people store and move this acid.
Keeping hydrochloric acid in the wrong kind of tank brings problems. I remember a chemical warehouse mixing up their plastic types—cracks appeared under sunlight, letting fumes escape. Polyethylene, polypropylene, and specific grades of PVC will hold up, but standard metal tanks can fall apart unless they’re lined correctly. Unlined steel or copper reacts badly, so acid eats right through unless barriers stand in the way. Glass carboys once popped up in labs, but they shatter too easily for any bulk storage. Real-world practice steers people toward plastic-lined steel tanks or dedicated plastic containers, kept shaded and out of direct heat. Overheating raises pressure, which makes leaks and vapor escape a dangerous reality.
Anyone who has carried out a hydrochloric acid transfer knows there’s no room for shortcuts. Only trained staff with clear tasks handle the transfer hoses, and I’ve seen the value in alarm systems on bulk tanks. Secondary containment—like bund walls—catches spills, offering a last barrier before acid hits soil or drains. Besides preventing accidents, good practice respects local laws. Regulators often require double-walled piping, secure labels, and round-the-clock monitoring. Without these checks, small mistakes can turn into public harm. In one case, a pump failure sent clouds of hydrochloric gas into a community, shutting schools for the day. Regular checks on seals, tank liners, and venting gear keep such risks at bay.
Driving a tanker of hydrochloric acid turns every bump in the road into a bigger responsibility. Not every transport company has the right trucks; only those with acid-resistant linings and top-notch venting systems qualify. DOT laws in many countries spell out how tankers travel, how often drivers refresh their training, and even which routes they take to avoid dense neighborhoods. Real experience shows that emergency kits must ride in the cab, carrying neutralizers and protective gear. Drivers need to know both the hazards and the step-by-step plans if something goes wrong. A minor crash in an unprepared truck could mean acid seeps onto streets or nearby rivers, threatening people and wildlife.
Improved practices around hydrochloric acid storage and transportation only come when companies invest in staff training and updated equipment. Continuous investment in monitoring gear, strict double-checks on labels, and fast spill response save communities from disaster. Mistakes cost more than money—they risk health and trust. Remembering why each rule exists, from the right plastic tank to full-face respirators, keeps everyone safer and the environment cleaner. For every tank and truck carrying hydrochloric acid, care, experience, and respect for the risks go a long way toward making sure this important chemical doesn’t become a danger.
If you’ve ever walked near a swimming pool supply shop or a factory that uses chemical treatments, you might have caught a whiff of a pungent, stinging smell. That’s hydrogen chloride for you. In the air, it mixes with water vapor and turns into hydrochloric acid, which attacks the eyes, nose, throat, and lungs. I worked for a summer cleanup crew at a warehouse that stored drums of industrial chemicals. A single leaky seal had people coughing, gasping for breath, and streaming tears. It’s tough to describe how fast this gas can make your lungs feel raw.
Short-term exposure leaves you with burning sensations, coughing fits, and sometimes chest pain. Over time or at high concentrations, the stuff scars the airways. Chronic breathing trouble stays with people long after they leave the facility. The U.S. Centers for Disease Control and Prevention lists long-term respiratory illness and dental corrosion as common fallout from repeated exposure. That’s not rare in places with poor air flow and not enough attention to safety.
Spills happen. In some factories, hydrochloric acid runs through pipes and vats, and workers handle it to clean metal or treat water. Gloves and safety shields give a bit of protection, but skin burns show up fast if those barriers fail. I’ve seen people freeze in panic when acid splashes up unexpectedly; drops on the skin sting at first, then turn red and blistered. Eyes take even more punishment—just a whiff in the air waters them, and direct contact can mean lasting injury or blindness.
Ingestion stories mostly come from poorly labeled bottles or workplace accidents, but even small sips can eat away at the mouth, throat, and stomach. Hospitals know that serious cases cause internal bleeding or organ damage. It reminds us that tight safety cultures save more than time and money—they keep people alive and healthy.
Factories and labs use hydrochloric acid by the ton. Spills and leaks find their way into soil, rivers, and lakes. What follows isn’t pretty. Acid lowers pH, which kills fish and plants in a hurry. I grew up near a creek where a single incident wiped out frogs, fish, and water bugs for the whole summer. There’s a ripple effect up the food chain; birds and mammals lose their meals, too.
Once hydrochloric acid gets loose, it doesn’t just vanish. Rain carries it further, and wind spreads hydrogen chloride gas over neighborhoods and farmland. Downwind crops suffer leaf burn and growth problems. Schools in industrial zones sometimes keep students indoors on high-risk days because of air quality alerts. One bad accident hurts people and sets back whole communities that rely on clean air and water.
Solutions start with better storage and handling; double-walled pipes, pressure checks, and chemical-resistant materials prevent leaks. Real training for workers (not just videos but live drills) prepares everyone to act fast during spills. Ventilation helps keep the air clear, while careful monitoring picks up slow leaks early. Local government inspections make a world of difference, if inspectors have real authority and enough staff to catch problems before disaster. Community right-to-know laws and public safety alerts warn neighbors of possible trouble.
Green chemistry has a role here, too. Some companies swap out harsh chemicals for gentler choices wherever possible. Creating safer alternatives, investing in accident-proof containers, and switching to closed process systems mean fewer folks pay the price. Working with chemicals like hydrochloric acid will always carry risk. Honest, proactive efforts from companies—driven by vigilant oversight and worker involvement—keep those risks from turning into headlines.
| Names | |
| Preferred IUPAC name | Chlorane |
| Other names |
Anhydrous hydrogen chloride Muriatic acid Chlorohydric acid Hydrochloric acid solution Spirit of salt |
| Pronunciation | /ˈhaɪdrə.dʒən ˈklɔː.raɪd ˌhaɪ.droʊˈklɔːr.ɪk ˈæs.ɪd/ |
| Identifiers | |
| CAS Number | 7647-01-0 |
| 3D model (JSmol) | `3D model (JSmol)` string for **Hydrogen Chloride (Hydrochloric Acid)**: ``` Cl[H] ``` |
| Beilstein Reference | 633873 |
| ChEBI | CHEBI:17883 |
| ChEMBL | CHEMBL1233378 |
| ChemSpider | 758 |
| DrugBank | DB09178 |
| ECHA InfoCard | 03b2d6b6-e9a9-4011-b678-85d5d8ce1956 |
| EC Number | 231-595-7 |
| Gmelin Reference | 822 |
| KEGG | C01327 |
| MeSH | D006741 |
| PubChem CID | 313 |
| RTECS number | MW4025000 |
| UNII | VU05T5D1QV |
| UN number | UN1789 |
| Properties | |
| Chemical formula | HCl |
| Molar mass | 36.46 g/mol |
| Appearance | Colorless to slightly yellow, fuming liquid with pungent, irritating odor |
| Odor | Pungent |
| Density | 1.18 g/cm³ (for 37% solution) |
| Solubility in water | Very soluble |
| log P | -1.49 |
| Vapor pressure | 40 atm (21°C) |
| Acidity (pKa) | -6.3 |
| Basicity (pKb) | -7 |
| Magnetic susceptibility (χ) | −25.9·10⁻⁶ cm³/mol |
| Refractive index (nD) | 1.332 |
| Viscosity | 1.9 mPa·s (at 15°C, for 37% solution) |
| Dipole moment | 1.08 D |
| Thermochemistry | |
| Std molar entropy (S⦵298) | 186.8 J/(mol·K) |
| Std enthalpy of formation (ΔfH⦵298) | −92.3 kJ·mol⁻¹ |
| Std enthalpy of combustion (ΔcH⦵298) | –92.3 kJ·mol⁻¹ |
| Pharmacology | |
| ATC code | B05XA07 |
| Hazards | |
| Main hazards | Corrosive, toxic by inhalation, causes severe burns, reacts violently with water and many chemicals, releases hazardous fumes. |
| GHS labelling | **GHS02, GHS05, GHS07, GHS08** |
| Pictograms | GHS05,GHS07 |
| Signal word | Danger |
| Hazard statements | H290, H314, H335 |
| Precautionary statements | P234, P260, P264, P271, P271+P403, P273, P280, P284, P301+P330+P331, P303+P361+P353, P304+P340, P305+P351+P338, P310, P321, P363, P405, P501 |
| NFPA 704 (fire diamond) | 3-0-2-Acid |
| Autoignition temperature | > 520°C (968°F) |
| Lethal dose or concentration | Lethal dose or concentration (Hydrogen Chloride / Hydrochloric Acid): "LC50 inhalation (rat): 3124 ppm (1-hour exposure) |
| LD50 (median dose) | LC50 inhalation (rat) 3124 ppm/1h |
| NIOSH | # string "MW4020000 |
| PEL (Permissible) | PEL: 5 ppm |
| REL (Recommended) | 5 ppm (7 mg/m³) |
| IDLH (Immediate danger) | 50 ppm |
| Related compounds | |
| Related compounds |
Hydrogen fluoride Hydrogen bromide Hydrogen iodide Ammonia Sulfuric acid |
