In early tests with the ligand 2-(2-Thiazolylazo)-p-cresol (TAC), we found that interference of the Fe(TAC) 1 complex may have competed with Fe(TAC) 2 for Fe. Also, i pmax was not reached in UV treated seawater after overnight equilibration ([TAC] = 40 Î¼ m, Î± Fe 3 + (TAC) 2 = 3.6 Ã 10 13).
BASE UNIT - kilogram (kg) - MASS. The standard for the kilogram is a cylinder of platinum-iridium alloy kept by the International Bureau of Weights and Measures in Paris. A duplicate at the National Bureau of Standards serves as the mass standard for the United States.
The mass of an atom is measured in atomic mass units (amu). An atom's mass can be found by summing the number of protons and neutrons. By definition, 12 amu equals the atomic mass of carbon-12. Protons and neutrons have an approximate mass of 1 amu, and electrons have a negligible mass. Usually, a pure element is made up of a number of isotopes in specific ratios. Because of this, the measured atomic mass of carbon is not exactly 12.