O2kg

O2kg is a nonstandard unit used informally to denote the mass of molecular oxygen (O2) expressed in kilograms. It is not part of the SI system and is not widely defined in scientific literature. In industry, O2kg can appear on supplier invoices or cylinder labels to indicate how much oxygen gas is present by mass rather than by volume.

Gases are compressible, so the same mass of O2 occupies different volumes depending on temperature and pressure. For practical handling, O2kg may be used alongside a pressure or volume specification, but it is the mass that is measured or bought, while the delivered gas is often specified in liters or cubic meters at a stated condition.

Conversions: At standard temperature and pressure (0°C, 1 atm), 1 kg of O2 is about 700 liters (0.70 cubic meters). At room temperature, about 25°C and 1 atm, 1 kg of O2 is roughly 760–765 liters. These values rely on the ideal gas law and vary with actual conditions.

Safety and labeling: Oxygen is nonflammable but supports combustion; containers require appropriate handling and storage. When O2kg is used, accompanying data typically include gas purity, cylinder pressure, and net weight.

Notes: The term O2kg is informal and not a standard unit; for precise calculations scientists typically rely on mass- or volume-based conventions that are consistent with established units and conditions.

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