Radioactive tracer such as a cell or tissue, or as a flow tracer to track fluid flow. Radioactive tracers are also used to determine the location of fractures created by hydraulic fracturing in natural gas production. Radioactive tracers form the basis of a variety of imaging systems, such as, PET scans, SPECT scans and technetium scans. Radiocarbon dating uses the naturally occurring carbon-14 isotope as an isotopic label. Isotopes of a chemical element differ only in the mass number. For example, the isotopes of hydrogen can be written as H, H and H, with the mass number at top left. When the
Hydrochloric acid Hydrochloric acid Hydrochloric acid is a colorless inorganic chemical system with the formula . Hydrochloric acid has a distinctive pungent smell. It is mainly produced as a precursor to vinyl chloride for PVC. It is classified as strongly acidic and can attack the skin over a wide composition range, since the hydrogen chloride practically dissociates completely in solution. Hydrochloric acid is the simplest chlorine-based acid system containing water. It is a solution of hydrogen chloride and water, and a variety of other chemical species, including hydronium and chloride ions. It is an important chemical reagent and industrial chemical, used primarily