The safety data sheet (SDS, formerly called MSDS) for acetic acid contains 16 standardized sections covering everything from its physical properties and health hazards to storage requirements, spill cleanup, and shipping classifications. Whether you’re handling it in a lab, a workplace, or reviewing it for a class, here’s what each section actually tells you.
Chemical Identity and Hazard Classification
The first three sections establish what acetic acid is and why it’s hazardous. Section 1 lists its chemical name, CAS registry number (64-19-7), molecular formula (CH3COOH), and the manufacturer’s contact information including an emergency phone number. Section 2 is the hazard identification, which is often the most immediately useful part of the entire document.
Acetic acid carries three GHS hazard classifications. It’s a Category 3 flammable liquid, meaning it can ignite under the right conditions. It causes Category 1 skin corrosion, the most severe rating, meaning it can produce burns, blisters, and scarring on contact. And it causes Category 1 serious eye damage, which means exposure can result in vision loss that may not fully reverse within 21 days. It’s also classified as Category 3 for acute inhalation toxicity, so breathing concentrated vapors can be poisonous.
The SDS displays three pictograms for these hazards: a flame symbol, a corrosion symbol (showing liquid damaging metal and skin), and a skull-and-crossbones for acute toxicity. The signal word is “Danger,” which is reserved for the more severe hazard categories.
Section 3, composition, confirms that glacial acetic acid is essentially pure (99% or higher) with a molecular weight of 60.05 g/mol.
First Aid and Emergency Response
Sections 4 through 6 cover what to do when something goes wrong. The first aid section (Section 4) breaks responses down by exposure route. For eye contact, the instruction is to irrigate immediately. Workplaces handling solutions above 5% concentration should have an eyewash station available. For skin contact, flush with water right away. Concentrations above 50% call for a quick-drench shower. If someone inhales acetic acid vapors, the priority is respiratory support and fresh air. If swallowed, the person needs immediate medical attention.
Section 5 covers firefighting. Acetic acid fires should be fought with dry chemical, CO2, or alcohol-resistant foam. Water jets are specifically not recommended, though a fine water spray is acceptable if foam isn’t available. When acetic acid burns, it produces irritating and toxic gases including carbon dioxide and other byproducts typical of burning organic material.
Section 6, accidental release measures, outlines spill containment and cleanup procedures: ventilating the area, preventing the liquid from reaching drains, and using appropriate absorbent materials.
Handling, Storage, and Incompatible Materials
Section 7 details how to safely work with and store acetic acid. This is where you’ll find one of the most practical pieces of information on the entire sheet: what not to let it contact. Acetic acid is incompatible with chromic acid, nitric acid, hydroxyl compounds, ethylene glycol, perchloric acid, peroxides, and permanganates. Mixing acetic acid with any of these can trigger violent or dangerous reactions. It should be stored away from these substances in a cool, well-ventilated area in corrosion-resistant containers.
Exposure Limits and Protective Equipment
Section 8 specifies how much acetic acid vapor workers can safely breathe and what protective gear to wear. OSHA sets the permissible exposure limit at 10 ppm (25 mg/m³) as an 8-hour time-weighted average. The ACGIH, an occupational health organization, agrees on 10 ppm as a time-weighted average but adds a ceiling limit of 15 ppm that should never be exceeded during any part of the workday.
For hand protection, the SDS typically recommends chemical-resistant gloves, but the specific material matters. For concentrated (glacial) acetic acid, laminate gloves like Silver Shield offer fair resistance with a breakthrough time around 37 minutes. Viton gloves perform similarly at about 38 minutes. Common lab gloves made of nitrile, natural rubber, or butyl don’t have reliable permeation data for glacial acetic acid, so they shouldn’t be trusted for handling it at full concentration. Safety goggles or a face shield, a chemical-resistant apron, and respiratory protection in poorly ventilated areas round out the standard recommendations.
Physical and Chemical Properties
Section 9 lists the measurable characteristics of acetic acid. It’s a clear, colorless liquid with a sharp, pungent vinegar smell. Key properties include its boiling point (around 118°C / 244°F), melting point (about 16.6°C / 62°F, which is why pure acetic acid freezes in a cool room and earned the name “glacial”), and a flash point near 39°C (102°F). It’s fully miscible with water, meaning it dissolves in any proportion. Its density is slightly higher than water at roughly 1.05 g/mL. These numbers help you assess ventilation needs, fire risk, and how the chemical behaves during a spill.
Stability, Reactivity, and Toxicology
Section 10 addresses stability and reactivity. Acetic acid is stable under normal storage conditions and does not undergo hazardous polymerization. However, it can react dangerously with strong oxidizers and the incompatible chemicals listed in Section 7. When heated to decomposition, it releases irritating and corrosive fumes.
Section 11, toxicological information, describes the health effects in more detail. Acute exposure to concentrated acetic acid causes severe chemical burns to skin and eyes. Inhalation of vapors irritates the respiratory tract and, at high concentrations, can cause serious lung damage. Chronic or repeated low-level exposure can lead to ongoing respiratory irritation, dental erosion, and skin problems. The section typically includes animal toxicity data (LD50 and LC50 values) that give researchers a quantitative measure of how toxic the substance is relative to other chemicals.
Environmental, Disposal, and Transport Information
Sections 12 through 14 cover what happens outside the lab or workplace. The ecological information section notes acetic acid’s behavior in water, soil, and air, along with its toxicity to aquatic organisms. Because it’s a naturally occurring organic acid, it biodegrades relatively quickly compared to many industrial chemicals, but concentrated releases can still harm aquatic life by lowering pH.
Section 13 provides disposal guidance. Acetic acid is typically neutralized before disposal or handled as hazardous waste depending on concentration and local regulations. You can’t just pour it down the drain at working concentrations.
Section 14 gives the shipping classification. Acetic acid’s UN number is 2790, and it falls under DOT Hazard Class 8 (corrosive). The proper shipping name depends on concentration. Solutions above 50% but at or below 80% have one designation, while solutions between 10% and 50% have another. Glacial acetic acid (essentially pure) ships under its own entry. This matters if you’re ordering, receiving, or transporting it.
Regulatory and Other Information
Section 15 lists the regulations that apply to acetic acid under various national and international frameworks, including its status on chemical inventories, reporting thresholds, and any special regulatory classifications. Section 16, the final section, includes the date the SDS was prepared or last revised, abbreviation definitions, and any other information the manufacturer considers relevant. Always check the revision date to make sure you’re working with current data.