Sec 1 Science Question

787180 SG

Material A is transparent,moderate strength,good heat conductivity and has high melting point? Give an example

Material B is transparent,moderate strength,poor heat conduvtivity and low melting point? Give an example

Material C is opaque,high strength,good heat conductivity,high melting point.

question 1) Suggest a possible identities of materials A & B

eg metals,plastics,glass,ceramics,fibres,etc

d3sT1nY SG

Eh, I only know how to answer the second part.

Choosing suitable material for science lab. Just look around and you'll find that glass is quite common.

Because it is transparent that you can see colour changes when you're conducting experiments.

Because it has extremely high melting point thus will not melt under normal bunsen burner flame. Therefore you can use it to contain liquids for boiling.

Because it is chemically stable and thus do not react with substances found in the lab.

These should answer the question. Haha.

SBS261P SG

A - glass

B - plastics

2) glass as d3sT1nY mentioned

3) availability of material (think $$$), chemical stability of material...

787180 SG

For material A…as suggested shd be glass but I thought glass retains heat eg glass milk bottle ie heat is not lost easily to outside hence glass shd be poor in heat conductivity..correct me if I’m wrong..thks to all of U who hve been very helpful indeed

d3sT1nY SG

Heat conductivity simply means how fast heat travels in that material. From one side of the material to the other side.

Heat is not lost easily to outside is quite subjective. As in if you were to compare it with other materials, maybe the other material will lost heat slower than glass. So glass actually loses heat quite quickly.

Now we can't quantify (or qualify, pardon my English) whether what's fast or what's slow unless we have experiments to prove it. (E.g Measure change in temperature of milk in 2 containers of different materials)

nightzip SG

Actually, thermal conductivity is a quantifiable unit, normally represented by the symbol, k, in units W/mK.

Seriously, I thought that is a bad question. Maybe can ask back the teacher when glass has good conductivity? and have him provide the thermal conductivity values for metal, glass and plastics. :)

Thermal Conductivity - k - (W/mK) Material/Substance Temperature (^oC) 25 125 225 Acetone 0.16 Acrylic 0.2 Air 0.024 Alcohol 0.17 Aluminum 250 255 250 Aluminum Oxide 30 Ammonia 0.022 Antimony 18.5 Argon 0.016 Asbestos-cement board 0.744 Asbestos-cement sheets 0.166 Asbestos-cement 2.07 Asbestos, loosely packed 0.15 Asbestos mill board 0.14 Asphalt 0.75 Balsa 0.048 Bitumen 0.17 Benzene 0.16 Beryllium 218 Brass 109 Brick dense 1.31 Brick work 0.69 Cadmium 92 Carbon 1.7 Cement, portland 0.29 Cement, mortar 1.73 Chalk 0.09 Cobalt 69 Concrete, light 0.42 Concrete, stone 1.7 Constantan 22 Copper 401 400 398 Corian (ceramic filled) 1.06 Corkboard 0.043 Cork, regranulated 0.044 Cork, ground 0.043 Cotton 0.03 Carbon Steel 54 51 47 Cotton Wool insulation 0.029 Diatomaceous earth (Sil-o-cel) 0.06 Earth, dry 1.5 Ether 0.14 Epoxy 0.35 Felt insulation 0.04 Fiberglass 0.04 Fiber insulating board 0.048 Fiber hardboard 0.2 Fireclay brick 500^oC 1.4 Foam Glass 0.042 Gasoline 0.15 Glass 1.05 Glass, Pearls, dry 0.18 Glass, Pearls, saturated 0.76 Class, window 0.96 Glass, wool Insulation 0.04 Glycerol 0.28 Gold 310 312 310 Granite 1.7 - 4.0 Gypsum or plaster board 0.17 Hairfelt 0.05 Hardboard high density 0.15 Hardwoods (oak, maple..) 0.16 Helium 0.142 Hydrogen 0.168 Ice (0^oC, 32^oF) 2.18 Insulation materials 0.035 - 0.16 Iridium 147 Iron 80 68 60 Iron, wrought 59 Iron, cast 55 Kapok insulation 0.034 Kerosene 0.15 Lead Pb 35 Leather, dry 0.14 Limestone 1.26 - 1.33 Magnesia insulation (85%) 0.07 Magnesium 156 Marble 2.6 Mercury 8 Methane 0.030 Methanol 0.21 Mica 0.71 Mineral wool blanket 0.04 Molybdenum 138 Monel 26 Nickel 91 Nitrogen 0.024 Nylon 6 0.25 Oil, machine 0.15 Olive oil 0.17 Oxygen 0.024 Paper 0.05 Paraffin Wax 0.25 Perlite, atmospheric pressure 0.031 Perlite, vacuum 0.00137 Plaster, gypsum 0.48 Plaster, metal lath 0.47 Plaster, wood lath 0.28 Plastics, foamed 0.03 Plastics, solid Platinum 70 71 72 Plywood 0.13 Polyethylene HD 0.42 - 0.51 Polypropylene 0.1 - 0.22 Polystyrene expanded 0.03 Porcelain 1.5 PTFE 0.25 PVC 0.19 Pyrex glass 1.005 Quarts mineral 3 Rock Wool insulation 0.045 Sand, dry 0.35 Sand, saturated 2.7 Sandstone 1.7 Sawdust 0.08 Silica aerogel 0.02 Silicone oil 0.1 Silver 429 Snow (temp < 0^oC) 0.05 - 0.25 Sodium 84 Softwoods (fir, pine ..) 0.12 Steel 46 Stainless Steel 16 17 19 Straw insulation 0.09 Styrofoam 0.033 Tin Sn 67 Zinc Zn 116 Urethane foam 0.021 Vermiculite 0.058 Vinyl ester 0.25 Water 0.58 Water, vapor (steam) 0.016 Wood across the grain, white pine 0.12 Wood across the grain, balsa 0.055 Wood across the grain, yellow pine 0.147 Wood, oak 0.17 Wool, felt 0.07

Deviancez SG

A - glass

B - plastics

2) glass as d3sT1nY mentioned

3) availability of material (think $$$), chemical stability of material...

Eh, but glass high heat conductivity meh?