Glass – a solid or a liquid?Kyle Foo (9)

Introduction

•Can we pour glass?•Can we draw a pint of glass?

What is glass made of

•Most common type of glass - soda-lime glass

•70-74% silica•Sodium carbonate to lower the melting

point to 1500°C to simplify processing•Lime, magnesium oxide and aluminum

oxide added to provide for a greater chemical durability

Who and how was glass discovered•the first true glass was made in coastal

north Syria, Mesopotamia or Old Kingdom Egypt

•The earliest known glass objects were beads

How glass is used

•Optical waveguides•Modern glass art•Windows•Etc.

Glass – a solid or a liquid?

Glass – an amorphous solid or a supercooled liquid?

The molecular structure of glassCrystal Glass

Conversion from liquid to solid for…Crystal Glass*

1. The liquid is cooled2. At the freezing point, the

molecules arrange themselves in a lattice

3. Intermolecular forces hold them together

4. It is now a solid

1. The liquid is cooled2. It remains liquid even

below its melting point and becomes supercooled

3. Its viscosity rises rapidly and continuously

4. It forms a thick syrup5. It eventually forms an

amorphous solid* The transition into glass only happens if the cooling rate is faster than the rate at which molecules can organize into a crystalline state

Characteristics of supercooled liquids•A liquid lowered below its freezing point

WITHOUT becoming a solid•exists in stratiform and cumulus clouds•there are freezers that supercools drinks

so that when it is opened it ‘slushes’ over

Characteristics of amorphous solids•No long-range atomic order•Has the properties of a solid•In principle, given a sufficiently high

cooling rate, any liquid can be made into an amorphous solid

•Examples are cotton candy, polystyrene, custard

Conclusion

I conclude that glass is an amorphous solid, as:

•It fits the criteria for being an amorphous solid, and

•It does not flow

Bibliography• http://en.wikipedia.org/wiki/Glass• http://www.beadfx.com/images/27800407-00.jpg• http://math.ucr.edu/home/baez/physics/General/Glass/glass.html• http://ocdeals.freedomblogging.com/files/2009/06/slurpee-web.jpg