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Sodium chloride / ˌ s oʊ d i ə m ˈ k l ɔːr aɪ d /, [8] commonly known as edible salt, is an ionic compound with the chemical formula NaCl, representing a 1:1 ratio of sodium and chlorine ions. It is transparent or translucent, brittle, hygroscopic , and occurs as the mineral halite .
Salt is also an ingredient in many manufactured foodstuffs. Table salt is a refined salt containing about 97 to 99 percent sodium chloride. [38] [39] [40] Usually, anticaking agents such as sodium aluminosilicate or magnesium carbonate are added to make it free-flowing. Iodized salt, containing potassium iodide, is widely available.
X-ray spectrometer developed by W. H. Bragg. In 1913 the structure of sodium chloride was determined by William Henry Bragg and his son William Lawrence Bragg. [2] [3] [4] This revealed that there were six equidistant nearest-neighbours for each atom, demonstrating that the constituents were not arranged in molecules or finite aggregates, but instead as a network with long-range crystalline ...
Both flasks are submerged in a dry ice/acetone cooling bath (−78 °C) the temperature of which is being monitored by a thermocouple (the wire on the left). A cooling bath or ice bath , in laboratory chemistry practice, is a liquid mixture which is used to maintain low temperatures, typically between 13 °C and −196 °C.
That is, the temperature and the compositions of all phases are determined. Thus, in for example the chemical system H 2 O-NaCl, which has two components, the simultaneous presence of the three phases liquid, ice, and hydrohalite can exist only at atmospheric pressure at the unique temperature of –21.2 °C [citation needed].
Sodium chloride and water form a eutectic mixture whose eutectic point is −21.2 °C [8] and 23.3% salt by mass. [9] The eutectic nature of salt and water is exploited when salt is spread on roads to aid snow removal, or mixed with ice to produce low temperatures (for example, in traditional ice cream making).
Halite is also often used both residentially and municipally for managing ice. Because brine (a solution of water and salt) has a lower freezing point than pure water, putting salt or saltwater on ice that is below 0 °C (32 °F) will cause it to melt—this effect is called freezing-point depression .
Note: ρ is density, n is refractive index at 589 nm, [clarification needed] and η is viscosity, all at 20 °C; T eq is the equilibrium temperature between two phases: ice/liquid solution for T eq < 0–0.1 °C and NaCl/liquid solution for T eq above 0.1 °C.