Wednesday, September 17, 2008

Laboratory Glasswares

Laboratory Glasswares

Laboratory glassware refers to a variety of equipment, traditionally made of glass, used for scientific experiment and other work in science, especially in chemistry & biology laboratories. Some of the equipment is now made of plastic for cost, ruggedness, and convenience reasons, but glass is still used for some applications because it is relatively inert, transparent, more heat-resistant than some plastic up to a point, and relatively easy to customize.

Types of Glass:

Soda-lime glass

  • The most prevalent type of glass. It can be processed so inexpensively that it is used for windowpanes and bottles.
  • The glass transition temperature (Tg) is about 730°C and the melting point is about 1000°C.Water containing powders of soda-lime glass exhibits alkalinity because Na+ and Ca2+ dissolve in it, leading to hydrolysis.

Borosilicate glass
  • Borosilicate glass is a type of heat-resistant glass
  • E.g. Pyrex
  • Borosilicate glass is created by adding boron to the traditional glassmaker's "frit" of silicate sand, soda, and ground lime
  • Has a very low thermal expansion coefficient
  • Less dense than ordinary glass
  • More resistant to thermal shock than other types of glass
  • can still crack or shatter when subject to rapid or uneven temperature variations

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