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Glass

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  • 1. GLASS Dr Sharipah Ruzaina Syed Aris
  • 2. GLASS
    • Non-crystalline solid because the atoms in glass are randomly arranged.
    • Hard, brittle and transparent material
    • No definite melting point but soften gradually when heated and resistant to chemicals
    • It is composed mainly of sand (silicates, SiO 2 ) and an alkali.
    • Is a mixture of sodium silicate, potassium silicate, calcium silicate and lead silicate.
  • 3. Properties of Glass
    • Solid and hard material
    • Disordered and amorphous structure
    • Fragile and easily breakable into sharp pieces
    • Transparent to visible light
    • Inert and biologically inactive material.
    • Glass is 100% recyclable and one of the safest packaging materials due to its composition and properties
    • Glass is used for architecture application, illumination, electrical transmission, instruments for scientific research, optical instruments, domestic tools and even textiles. Glass does not deteriorate, corrode, stain or fade and therefore is one of the safest packaging materials.
  • 4. TYPES OF GLASS
    • Soda lime glass
    • Soda-lead glass
    • Borosilicate glass
    • Fused silica glass
  • 5. Soda lime glass
    • Most common and less expensive.
    • The composition of soda-lime glass is normally 60-75% silica (sand), 12-18% soda, and 5-12% lime.
    • Appropriate to be use in flat glass in windows (light transmission)
    • It has a smooth and nonporous surface that allows glass bottles and packaging glass to be easily cleaned
    • resistant to chemical attack from aqueous solutions so they will not contaminate the contents inside or affect the taste.
    • Some of the use of soda-lime glass is primarily used for bottles, jars, everyday drinking glasses, and window glass.
  • 6. Soda-lead glass
    • Composed of 54-65% SiO 2 , 18-38% lead oxide (PbO), 13-15% soda (Na 2 O) or potash (K 2 ), and various other oxides.
    • When the content of PbO is less than 18% is known as crystal glass.
    • Easy to melt and much more expensive than soda-lime glass.
    • It has a high refractive index giving high brilliance glass (sparkles).
    • Make it appropriate for decorating purposes.
  • 7. Borosilicate glass
    • composed of silica (70-80%), boric oxide B 2 O 3 (7-13%) and smaller amounts of the alkalis ( sodium and potassium oxides) such as 4-8% of Na 2 O and K 2 O, and 2-7% aluminum oxide (Al 2 O 3 ).
    • Greater resistance to thermal changes and chemical corrosion.
    • Used in the home for cooking plates and other heat-resistant products. It is used for domestic kitchens and chemistry laboratories, this is because it has greater resistance to thermal shock and allows for greater accuracy in laboratory measurements when heating and cooling experiments.
  • 8. Fused silica glass
    • Almost 100% silica
    • Highly heat-shock resistant glass
    • Can be heated to extremely high temperatures and then plunged into ice-cold water without cracking.
    • Expensive
    • Use in laboratory glassware and optical fibers
  • 9. Coloured glass
    • By adding certain oxides. Exp:
    Colour of the glass Chemicals Red Gold, copper, selenium oxides Blue Cobalt and copper silicate Green Chromium and ferrous oxide Opalescent Calcium phosphate Yellow Ferric oxide