Attribute	Ammonia	Ammonia
Refers to	Ammonia (anhydrous)	Ammonia (anhydrous)
CAS Registry Number	7664-41-7	7664-41-7
Molecular formula	H3N	H3N
Molar mass	17.031 g/mol	17.031 g/mol
Typical name domain	Repeated term — class/brand/formulation context decides	Repeated term — class/brand/formulation context decides
Chemically different substance?	No	No
Lewis structure guide	Ammonia Lewis structure	Ammonia Lewis structure

Context	Term Used	What Must Be Verified
Pressure cylinders, refrigeration, bulk	Ammonia, anhydrous	NH3 ≥99.5%; cylinder and hazard-class language governs.
Lab bottles, pharma synthesis	Ammonia solution / ammonia water	15–35% NH3 in water; concentration is the spec.
Fertilizer and analytical	Ammonium salts	NH4+ as sulfate/nitrate/chloride; solid handling.

Never accept “ammonia” alone on an order line. Require CAS, concentration or assay, and container type; aqueous and anhydrous forms differ in hazard class, shipping and reactor design.

Because the substance is identical either way, grade and documentation do the real separating: pharmacopoeial vs food vs technical grade, assay basis, impurity limits (heavy metals, residual solvents, water), container size and, for stereochemical names, an optical-purity clause.

Are Ammonia and Ammonia chemically identical?

Yes. The query repeats one name, so the real procurement ambiguity is physical form, not spelling: anhydrous ammonia gas (CAS 7664-41-7), aqueous ammonia solution (CAS 1336-21-6), and ammonium salts are three different orderable products.

Both map to CAS 7664-41-7.

Which spelling is correct?

Both are accepted, but in different domains: The query repeats one name, so the useful content is what the term actually designates in trade.

Controlled documents should use the qualified form and always add the CAS.

What should a purchase order say?

Name plus CAS plus grade plus quantity. For Ammonia (anhydrous) the CAS alone removes every ambiguity created by spelling, shorthand or stereochemistry prefixes.

What are the most common mix-ups with this term?

Never accept “ammonia” alone on an order line. Require CAS, concentration or assay, and container type; aqueous and anhydrous forms differ in hazard class, shipping and reactor design.

Editorial note

This article clarifies naming equivalence for procurement and documentation use. It is not legal or regulatory advice; the controlled source for any label is the current monograph, CAS index entry and applicable market regulations.