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| Thread ID: 57000 | 2005-04-20 21:20:00 | A Chemistry Question | Renmoo (66) | PC World Chat |
| Post ID | Timestamp | Content | User | ||
| 347093 | 2005-04-21 02:13:00 | However it is a very reactive metal, (isn't it near to potassium and sodium in the periodic table? )so it always has an oxide layer on it's surface. You can't physically remove the oxide layer as it forms again very fast.From memory a Mercury compound can be used to remove the oxide coating (briefly) to provide for some great reactions. | ninja (1671) | ||
| 347094 | 2005-04-21 04:01:00 | And, of course stainless steel is a terrible conductor of heat. It's used for cookware because it's easy to make it shiny. (It's not even stainless. It is stain "resistant".) Good stainless ware has a heavy copper bottom to help moving heat from the stove to the food. Cheap stainless ware has a light copper plating to look as if it has copper to help ... Your hot water cylinder is copper. This is because its heat capacity is small. Copper cooking utensils would be the best, but some foods can produce poisonous compunds with it. A tin coating helps, but that's too soft to last. Aluminium is used for power transmission lines because it's a bit lighter than copper, and it costs less. The lightness is not a great benefit, because it's not as good a conductor so you have to use bigger wires. There are still some problems in joining copper to aluminium ... they make a good "battery" when they get wet, and the corrosion this causes rots the aluminium fairly quickly. |
Graham L (2) | ||
| 347095 | 2005-04-21 04:36:00 | Science in the kitchen can be quite interesting. For example Birds Custard Powder when a small quantity of water is added and stirred is quite thixotropic, ( I think that is the right word), if stirred vigorously it crumbles, and then when stirring is stopped it reforms to a liquid paste. A good flat bottomed aluminium saucepan, preferably with a machined surface rather than spun, when kept cool with water in it, and placed on a bright red-hot electric element (stainless steel), will exhibit very low friction. When the element is switched off, and it cools, you can feel the saucepan 'grab' on the element as the friction coefficient jumps back up. There is scope here for a Friction and Wear' research paper :rolleyes: |
Terry Porritt (14) | ||
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