- What it is. This ammonium hydroxide 50% (v/v) solution is a 1+1 dilution: one volume of concentrated 28 to 30% ammonium hydroxide mixed with one volume of water, supplied in a 500 mL size. Many ASTM, EPA, and standard methods call for ammonium hydroxide (1+1) by name, and this product supplies it ready to use.
- Reading method notation. Analytical methods often specify reagent dilutions as volume ratios rather than molarity. In that notation, 1+1 means one part concentrated reagent plus one part water, equivalent to 50% by volume, while 1+4 or 1+19 indicate weaker dilutions. Using a pre-made 1+1 solution keeps a method's reagent exactly as written.
- How strong it is. Because it contains half the volume of concentrate, this solution is roughly 7 to 7.5 molar as NH3, calculated from a 14.5 to 15 M concentrate. Its density is about 0.94 g/mL. It remains strongly alkaline and corrosive, but it fumes noticeably less than full-strength ammonium hydroxide.
- Why buy it pre-diluted. Diluting concentrated ammonia releases heat and a burst of ammonia vapor, and small measuring errors change the final strength. A pre-made 1+1 solution removes that step, reduces bench exposure, saves preparation time, and delivers the same strength every time a method references it.
- Chemistry in use. Like the concentrate, it is a weak base that neutralizes acids, forms ammonium salts, and raises pH into the alkaline range. It precipitates iron and aluminum as hydroxides and forms soluble ammine complexes with copper, silver, nickel, and zinc, reactions that drive many separation and qualitative analysis steps.
- Where it is used. Analysts use it to raise sample pH after acid digestion, precipitate metal hydroxides in gravimetric methods, neutralize acid residues before disposal, and build ammonia buffers at working strength with fewer fumes. For full-strength work, see Lab Pro's Ammonium Hydroxide 28 to 30% Solution, ACS Grade.
- Handling at a glance. Even at half strength, the solution causes severe skin burns and eye damage and releases irritating ammonia vapor. Work in a fume hood, wear splash goggles and chemical-resistant gloves, and never combine it with bleach or other chlorine sources.
Technical Specifications
| Active Ingredient | Ammonium hydroxide |
| CAS Number | 1336-21-6 (ammonium hydroxide); 7732-18-5 (water) |
| EC Number (active) | 215-647-6 |
| Formula (active) | NH4OH (NH3 in H2O) |
| Molecular Weight (active) | 35.05 g/mol |
| Concentration | 50% (v/v), equivalent to 1+1 |
| Approximate Molarity | 7 to 7.5 M as NH3 (calculated) |
| Density | About 0.94 g/mL |
| Appearance | Clear, colorless liquid |
| Odor | Pungent ammonia odor |
| Solubility | Miscible with water |
| Package Size | 500 mL |
Applications / Common Uses
- Standard method reagent: Supplies the ammonium hydroxide (1+1) called for in many ASTM, EPA, and APHA procedures.
- pH adjustment during sample prep: Raises pH after acid digestion before analysis or precipitation.
- Gravimetric precipitation: Precipitates iron, aluminum, and other metal hydroxides.
- Acid neutralization: Neutralizes acid residues on labware and in waste streams before disposal.
- Buffer preparation: Builds ammonia buffers at working strength with fewer fumes than the concentrate.
Storage, Handling & Shipping
Caution: Ammonium hydroxide 50% (v/v) causes severe skin burns and eye damage and releases irritating ammonia vapor. Work in a fume hood with splash goggles, a face shield for larger volumes, and nitrile or neoprene gloves. Never mix with bleach or other chlorine sources.
Store this solution tightly closed in a cool, ventilated corrosives area away from heat and sunlight, which drive off ammonia and build pressure in closed containers. Keep it separate from acids, oxidizers, halogens, and bleach, and away from copper, brass, and zinc. Open it slowly inside a fume hood with your face turned away, and close it promptly to preserve strength.
- Incompatible materials: Acids, strong oxidizers, halogens, hypochlorite (bleach), copper, brass, zinc, and aluminum.
- Exposure limits (ammonia): OSHA PEL 50 ppm TWA; NIOSH REL 25 ppm TWA, 35 ppm STEL.
- Spill response: Ventilate, contain with an inert absorbent, and collect for disposal. Keep vapors out of drains and enclosed spaces.
- First aid: Skin or eyes: flush with water for at least 15 minutes and seek medical attention. Inhalation: move to fresh air.
- GHS signal word: Danger. Causes severe skin burns and eye damage.
- DOT / shipping: UN2672, Ammonia solution, Class 8, Packing Group III.
Related Categories & Services
- Shop Bases for related products in this category.
- Explore Inorganic Chemicals 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
What does ammonium hydroxide (1+1) mean in a method?
The notation 1+1 means one volume of concentrated reagent mixed with one volume of water, which is the same as 50% by volume. Methods use it to specify a working strength without listing molarity. This product is prepared to that ratio, so you can use it as written without diluting the concentrate yourself.
How strong is 50% v/v ammonium hydroxide compared with the concentrate?
It contains about half the ammonia of 28 to 30% ammonium hydroxide, roughly 7 to 7.5 molar as NH3 by calculation. That is still strongly alkaline and corrosive, so the same PPE applies. The main practical difference is less fuming and a gentler pH change when you add it to samples.
Why buy a pre-diluted ammonium hydroxide solution?
Diluting concentrated ammonia releases heat and a surge of vapor, and measuring errors change the final strength. A ready-made 1+1 solution avoids that exposure, saves preparation time, and keeps results consistent from batch to batch. It is especially useful in labs that run standard methods daily.
Does 50% ammonium hydroxide lose strength over time?
Yes, slowly. Ammonia escapes when the container is open or warm, gradually lowering the concentration. Keep it tightly closed, store it in a cool area, and avoid leaving it open on the bench. If your method depends on an exact strength, verify it by titration before critical work.
Can I mix this ammonium hydroxide solution with bleach?
No. Any ammonia solution reacts with sodium hypochlorite and other chlorine sources to release chloramine gases, which can cause serious lung injury. Store ammonium hydroxide and bleach separately; never mix them in cleaning or waste containers, and rinse equipment thoroughly when switching between the two.
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