Search results
Results From The WOW.Com Content Network
The structure of sodium oxide has been determined by X-ray crystallography.Most alkali metal oxides M 2 O (M = Li, Na, K, Rb) crystallise in the antifluorite structure.In this motif the positions of the anions and cations are reversed relative to their positions in CaF 2, with sodium ions tetrahedrally coordinated to 4 oxide ions and oxide cubically coordinated to 8 sodium ions.
An example batch calculation may be demonstrated here. The desired glass composition in wt% is: 67 SiO 2, 12 Na 2 O, 10 CaO, 5 Al 2 O 3, 1 K 2 O, 2 MgO, 3 B 2 O 3, and as raw materials are used sand, trona, lime, albite, orthoclase, dolomite, and borax.
The molar mass of atoms of an element is given by the relative atomic mass of the element multiplied by the molar mass constant, M u ≈ 1.000 000 × 10 −3 kg/mol ≈ 1 g/mol. For normal samples from Earth with typical isotope composition, the atomic weight can be approximated by the standard atomic weight [ 2 ] or the conventional atomic weight.
It is necessary to calculate the mass of a solid acid which will react with about 20 cm 3 of this solution (for a titration using a 25 cm 3 burette): suitable solid acids include oxalic acid dihydrate, potassium hydrogen phthalate and potassium hydrogen iodate. The equivalent weights of the three acids 63.04 g, 204.23 g and 389.92 g ...
Atomic number Element Molar mass Formal standard atomic weight s.a.w., formal short Note Z calculated; g·mol −1 A r, standard [2] A r, abridged and conventional [2]; C 9 H 8 O 4: 180.159 g·mol −1
Each element has an atomic mass, and considering molecules as collections of atoms, compounds have a definite molecular mass, which when expressed in daltons is numerically equal to the molar mass in g/mol. By definition, the atomic mass of carbon-12 is 12 Da, giving a molar mass of 12 g/mol.
When the prevalences of interest are those of individual chemical elements, rather than of compounds or other substances, the term mass fraction can also refer to the ratio of the mass of an element to the total mass of a sample. In these contexts an alternative term is mass percent composition.
The molecular mass and relative molecular mass are distinct from but related to the molar mass. The molar mass is defined as the mass of a given substance divided by the amount of the substance, and is expressed in grams per mol (g/mol). That makes the molar mass an average of many particles or molecules (potentially containing different ...