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An overview of ranges of mass. To help compare different orders of magnitude, the following lists describe various mass levels between 10 −67 kg and 10 52 kg. The least massive thing listed here is a graviton, and the most massive thing is the observable universe.
The term combines the SI prefix nano-indicating a 1 billionth submultiple of an SI unit (e.g. nanogram, nanometre, etc.) and second, the primary unit of time in the SI. A nanosecond is to one second, as one second is to approximately 31.69 years. A nanosecond is equal to 1000 picoseconds or 1 / 1000 microsecond.
There is a risk of serious consequences when abbreviations are misread or misinterpreted. In the United Kingdom, all prescriptions should be in English without abbreviation (apart from some units such as mg and mL; micrograms and nanograms should not be abbreviated). [5]
1795: the gram (1 / 1000 of a kilogram) was provisionally defined as the mass of one cubic centimetre of water at the melting point of ice. [12] 1799: The Kilogramme des Archives was manufactured as a prototype. It had a mass equal to the mass of 1 dm 3 of water at the temperature of its maximum density, which is approximately 4 °C. [13]
For example, the conversion factor between a mass fraction of 1 ppb and a mole fraction of 1 ppb is about 4.7 for the greenhouse gas CFC-11 in air (Molar mass of CFC-11 / Mean molar mass of air = 137.368 / 28.97 = 4.74). For volume fraction, the suffix "V" or "v" is sometimes appended to the parts-per notation (e.g. ppmV, ppbv, pptv).
The LD 50 is usually expressed as the mass of substance administered per unit mass of test subject, typically as milligrams of substance per kilogram of body mass, sometimes also stated as nanograms (suitable for botulinum), micrograms, or grams (suitable for paracetamol) per kilogram. Stating it this way allows the relative toxicity of ...
An equivalent (symbol: officially equiv; [1] unofficially but often Eq [2]) is the amount of a substance that reacts with (or is equivalent to) an arbitrary amount (typically one mole) of another substance in a given chemical reaction.
Historically, the mole was defined as the amount of substance in 12 grams of the carbon-12 isotope.As a consequence, the mass of one mole of a chemical compound, in grams, is numerically equal (for all practical purposes) to the mass of one molecule or formula unit of the compound, in daltons, and the molar mass of an isotope in grams per mole is approximately equal to the mass number ...