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 at 180°). The author suggests that HO may become more important in dilute HCl solutions. ("See" hydronium ion "for further discussion of this issue.") Hydrochloric acid is a strong acid, since it is completely dissociated in water. It can therefore be used to prepare salts containing the Cl anion called "chlorides". As a strong acid, hydrogen chloride has a large "K". Theoretical attempts to assign the p"K" of hydrogen chloride have been made, with the most recent estimate being −5.9. However, it is important to distinguish between hydrogen chloride gas and hydrochloric acid. Due to the leveling effect, except when