- What it is. This hydrochloric acid solution is a standardized 6.0 N (6.0 M) acid, available in 1 quart and 1 gallon sizes. It is a corrosive, moderately fuming acid used for digestion, hydrolysis, and sample dissolution.
- Molar equals normal. Hydrochloric acid releases one hydrogen ion per molecule, so 6.0 N equals 6.0 M. Each liter contains about 218.8 g of hydrogen chloride, and each milliliter neutralizes 6.0 millimoles of base (calculated).
- Why 6 N HCl is so widely used. Six-molar hydrochloric acid is the classic strength for acid hydrolysis of proteins and peptides before amino acid analysis, typically at about 110 °C for around 24 hours. It is also a standard strength for dissolving metals, minerals, and residues in sample preparation.
- A defined strength instead of an estimate. Diluting concentrated acid 1+1 gives roughly 6 M, but the exact value varies. A standardized 6.0 N solution gives a defined concentration, which matters for hydrolysis and digestion methods that specify 6 N acid.
- Metal and mineral digestion. Six-normal hydrochloric acid dissolves many metals, metal oxides, and carbonate minerals, making it a standard reagent for preparing samples for elemental analysis and removing deposits from equipment.
- Diluting to working strengths. From 6.0 N, mixing 1 part acid with 5 parts water gives 1.0 N (calculated). Always add acid to water slowly, mix, and allow the solution to cool before final dilution.
- Handling at a glance. Work in a fume hood, especially when heating, and wear chemical splash goggles and acid-resistant gloves. Store containers in a ventilated corrosives cabinet away from bases, oxidizers, and metals.
- Related products. For approximately 6 M acid in larger volume, see Lab Pro's Hydrochloric Acid 50% (v/v), 3.8 L. For concentrated acid to prepare custom strengths, see Hydrochloric Acid 37%, ACS Grade.
- Two sizes for different workloads. The 1 quart size (ZH0609-32) suits occasional digestions and hydrolyses, while the 1 gallon size (ZH0609-128) supports labs that prepare samples daily.
- Where it is used. Laboratories use 6 N HCl for protein and peptide hydrolysis, metal and mineral digestion, dissolving carbonates and oxides, acidifying samples, qualitative analysis schemes, and preparing weaker acid solutions.
Technical Specifications
| Chemical Name | Hydrochloric acid, aqueous solution |
| CAS Numbers | 7647-01-0 (hydrogen chloride); 7732-18-5 (water) |
| EC Number (HCl) | 231-595-7 |
| Synonyms | Hydrogen chloride solution, muriatic acid, spirits of salt |
| Formula (active) | HCl |
| Molecular Weight (active) | 36.46 g/mol |
| Concentration | 6.0 N (6.0 M) |
| HCl Content | About 218.8 g/L (calculated) |
| Neutralizing Capacity | 1.00 mL = 6.00 mmol base (calculated) |
| Appearance | Clear, colorless liquid |
| Physical State | Liquid, aqueous solution |
| Hazard Statements (typical) | Causes severe skin burns and eye damage; may cause respiratory irritation |
| DOT (comparable products) | UN1789, Hydrochloric acid, Class 8 (PG II or III by supplier) |
| Storage | Corrosives cabinet, tightly closed |
| Package Sizes | 1 quart; 1 gallon |
Available Variants
- ZH0609-32: 1 quart for occasional digestion and hydrolysis.
- ZH0609-128: 1 gallon for daily sample preparation.
Applications / Common Uses
- Protein hydrolysis: Breaks proteins into amino acids for analysis.
- Metal and mineral digestion: Dissolves samples before analysis.
- Carbonate dissolution: Dissolves carbonate and oxide residues.
- Qualitative analysis: Supplies chloride and acidity in classic schemes.
- Acid dilutions: Prepares 1 N and other working strengths.
Storage, Handling & Shipping
Caution: 6 N hydrochloric acid causes severe skin burns and eye damage and releases irritating fumes, especially when warm. Handle in a fume hood with chemical splash goggles, a face shield for larger volumes, and acid-resistant gloves.
Store tightly closed in a cool, well-ventilated corrosives cabinet, away from bases, oxidizers, metals, and cyanide or sulfide salts, which release toxic gases with acid. When diluting, always add acid slowly to water, never water to acid.
- Incompatible materials: Bases, oxidizers (including bleach and permanganate), reactive metals, cyanides, and sulfides.
- Exposure limit (hydrogen chloride): OSHA PEL and NIOSH REL: 5 ppm ceiling.
- Spill response: Ventilate, contain, and neutralize with sodium bicarbonate or an acid spill kit before cleanup.
- First aid: Skin or eyes: flush with water for at least 15 minutes and seek medical attention. Inhalation: move to fresh air.
Related Categories & Services
- Shop Acids for related products in this category.
- Explore Buffers, Standards & Solutions and ACS Grade Laboratory Chemicals.
- Vendor Managed Inventory (VMI) Program: Lab Pro can stock, track, and replenish this item on site so it never runs out. Contact info@labproinc.com or 888-452-2776 to set up a VMI assessment.
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FAQs
Why is 6 N HCl used for protein hydrolysis?
Six-molar hydrochloric acid at about 110 °C breaks peptide bonds completely over roughly 24 hours, releasing amino acids for analysis. The strength is high enough for complete hydrolysis while remaining practical to handle in sealed tubes, which is why it became the standard condition. Samples are typically heated in sealed tubes.
Is 6 N HCl the same as diluting concentrated acid 1+1?
A 1+1 dilution of 37% hydrochloric acid gives roughly 6 M, but the exact value varies with the starting acid. A standardized 6.0 N solution has a defined concentration, which matters when methods specify 6 N acid for hydrolysis or digestion. Using a standardized acid removes that uncertainty.
How do I make 1 N HCl from 6 N?
Measure 1 part of 6.0 N acid and add it slowly to 5 parts of deionized water, for example 166.7 mL acid diluted to 1 liter. Mix, let the solution cool, and standardize it if your method requires an exact concentration. Always add acid to water.
What PPE is required for 6 N HCl?
Wear chemical splash goggles, acid-resistant gloves, and a lab coat, and work in a fume hood, especially when heating. Add a face shield for larger volumes. Keep an eyewash station and an acid spill kit nearby whenever you handle or heat the acid. Rinse splashes with plenty of water.
Which size should I choose?
Choose the quart for occasional hydrolyses or digestions so stock is used while fresh. Choose the gallon for daily sample preparation, which supplies one consistent lot over a longer period and reduces how often the strength needs to be verified. Both sizes contain the same solution.
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