Search results
Results From The WOW.Com Content Network
Pure water is an example of a chemical substance, with a constant composition of two hydrogen atoms bonded to a single oxygen atom (i.e. H 2 O). The atomic ratio of hydrogen to oxygen is always 2:1 in every molecule of water. Pure water will tend to boil near 100 °C
In chemistry, chemical purity is the measurement of the amount of impurities found in a sample.Several grades of purity are used by the scientific, pharmaceutical, and industrial communities.
Purification in a chemical context is the physical separation of a chemical substance of interest from foreign or contaminating substances. Pure results of a successful purification process are termed isolate. The following list of chemical purification methods should not be considered exhaustive.
Any substance consisting of two or more different types of atoms (chemical elements) in a fixed stoichiometric proportion can be termed a chemical compound; the concept is most readily understood when considering pure chemical substances.
Some chemical substances can be combined or converted into new substances by means of chemical reactions. Chemicals that do not possess this ability are said to be inert. Pure water is an example of a chemical substance, with a constant composition of two hydrogen atoms bonded to a single oxygen atom (i.e. H 2 O).
Firstly, a pure chemical should appear in at least one chemical phase and can also be characterized by its phase diagram. Secondly, a pure chemical should prove to be homogeneous (i.e., a uniform substance that has the same composition throughout the material [2]). The perfect pure chemical will pass all attempts to separate and purify it further.
This allows it to be the "solvent of life": [48] indeed, water as found in nature almost always includes various dissolved substances, and special steps are required to obtain chemically pure water. Water is the only common substance to exist as a solid, liquid, and gas in normal terrestrial conditions. [49]
In chemistry, a pure element means a substance whose atoms all (or in practice almost all) have the same atomic number, or number of protons. Nuclear scientists, however, define a pure element as one that consists of only one isotope. [18] For example, a copper wire is 99.99% chemically pure if 99.99% of its atoms are copper, with 29 protons each.