GlassGlass

Miss JanMiss Jan

Page 46 practicalPage 46 practical

1.1. Cut glass – use fileCut glass – use file

2.2. ““Melt” glass and smooth the end of the tubeMelt” glass and smooth the end of the tube

3.3. Heat the middle of the tube, then put the two Heat the middle of the tube, then put the two unheated ends to make the middle thinnerunheated ends to make the middle thinner

4.4. Bend glassBend glass

► Complete the table at the bottom of page 46Complete the table at the bottom of page 46

WEAR SAFETY GLASSES AT ALL TIMES

ALL glass must return to the container

Natural glass: Natural glass: Obsidian

Relay reading – NMS 2 pages Relay reading – NMS 2 pages 50-5150-51

►Work in pairsWork in pairs►Person on the left read page 50 – Person on the left read page 50 –

write down 3 important pointswrite down 3 important points►Person on the right read page 51 – Person on the right read page 51 –

write down 3 important pointswrite down 3 important points

Glass – solid…??Glass – solid…??

Compare the plastics with Compare the plastics with glassglass

Plastic Glass

NMS 2 p51NMS 2 p511.1. Glass was first made when soda Glass was first made when soda

(sodium carbonate) was (sodium carbonate) was accidentally heated with sand accidentally heated with sand (silicon dioxide). These (silicon dioxide). These compounds react like this:compounds react like this:

sodium carbonate

+ silicon dioxide sodium silicate +carbon dioxide

Na2CO3 + SiO2 Na2SiO3 + CO2

2.2. The raw materials used in making glass The raw materials used in making glass are:are:

silicon dioxidesilicon dioxide

sodium oxidesodium oxide

calcium oxidecalcium oxide

Other compounds can be added to make Other compounds can be added to make glass with different properties (such as glass with different properties (such as colour).colour).

3.3. Different types of glass include:Different types of glass include:

Soda glassSoda glass – the “ordinary” glass used for most – the “ordinary” glass used for most purposespurposes

Borosilicate glassBorosilicate glass – which contains boron, is – which contains boron, is tougher and is able to resist higher temperatures tougher and is able to resist higher temperatures and so is used in cookware and lab equipmentand so is used in cookware and lab equipment

Cut glassCut glass – which contains lead, is more “sparkly” – which contains lead, is more “sparkly” and is used in ornaments and costume jewelleryand is used in ornaments and costume jewellery

Fibreglass Fibreglass – consists of a bundle of glass fibres – consists of a bundle of glass fibres embedded in plastic and is used to support and embedded in plastic and is used to support and strengthen the plasticstrengthen the plastic

Safety glassSafety glass – consists of a layer of plastic used to – consists of a layer of plastic used to hold two sheets of glass together so that the hold two sheets of glass together so that the glass doesn’t shatter when it’s brokenglass doesn’t shatter when it’s broken

4.4. Properties and uses of glass include:Properties and uses of glass include:

Property Use

Reasonably low melting point can be easily shaped into different objects

Transparent to light glasses (both kinds)

Attractive shiny appearance ornaments

Electrical insulator heavy duty electrical fittings

Insoluble in water hold drinks like wine and beer

Chemically unreactive can be safely used with a wide range of materials

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a.a. Light bulbs – transparent, easily moulded, Light bulbs – transparent, easily moulded, doesn’t react with oxygen, even at high doesn’t react with oxygen, even at high temperaturestemperatures

b.b. TV screens – transparent, easily mouldedTV screens – transparent, easily moulded

c.c. Telescopes – transparent, easily moulded Telescopes – transparent, easily moulded into different shapes of lensesinto different shapes of lenses

d.d. Drink bottles – transparent, easily Drink bottles – transparent, easily moulded, doesn’t react chemically with water moulded, doesn’t react chemically with water and dilute solutions of weak acids (fruit juices)and dilute solutions of weak acids (fruit juices)

e.e. Acid bottles – transparent, easily Acid bottles – transparent, easily moulded, doesn’t react even with moulded, doesn’t react even with concentrated solutions of strong acidsconcentrated solutions of strong acids