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In most of the world, recipes use the metric system of units—litres (L) and millilitres (mL), grams (g) and kilograms (kg), and degrees Celsius (°C). The official spelling litre is used in most English-speaking nations; the notable exception is the United States where the spelling liter is preferred.
The kilogram is the only base SI unit with an SI prefix (kilo) as part of its name. The word kilogramme or kilogram is derived from the French kilogramme, [15] which itself was a learned coinage, prefixing the Greek stem of χίλιοι khilioi "a thousand" to gramma, a Late Latin term for "a small weight", itself from Greek γράμμα. [16]
The scope of the directive is limited to prepackages that have a predetermined nominal weight of between 5 g and 10 kg or volume of 5 ml and 10 L, are filled without the purchaser present, and in which the quantity cannot be altered without opening or destroying the packing material.
To create the solution, 11.6 g NaCl is placed in a volumetric flask, dissolved in some water, then followed by the addition of more water until the total volume reaches 100 mL. The density of water is approximately 1000 g/L and its molar mass is 18.02 g/mol (or 1/18.02 = 0.055 mol/g). Therefore, the molar concentration of water is
The base units are defined in terms of the defining constants. For example, the kilogram is defined by taking the Planck constant h to be 6.626 070 15 × 10 −34 J⋅s, giving the expression in terms of the defining constants [1]: 131 1 kg = (299 792 458) 2 / (6.626 070 15 × 10 −34)(9 192 631 770) h Δν Cs / c 2 .
The kilogram is the only standard unit to include an SI prefix (kilo-) as part of its name. The gram (10 −3 kg) is an SI derived unit of mass. However, the names of all SI mass units are based on gram, rather than on kilogram; thus 10 3 kg is a megagram (10 6 g), not a *kilokilogram.
It is equivalent to the units gram per millilitre (g/mL) and kilogram per litre (kg/L). The density of water is about 1 g/cm 3, since the gram was originally defined as the mass of one cubic centimetre of water at its maximum density at 4 °C (39 °F). [1]
In chemistry, the mass concentration ρ i (or γ i) is defined as the mass of a constituent m i divided by the volume of the mixture V. [1]= For a pure chemical the mass concentration equals its density (mass divided by volume); thus the mass concentration of a component in a mixture can be called the density of a component in a mixture.