| Electronics > Projects, Designs, and Technical Stuff |
| Does anyone know the boiling point of solder (yes boiling) |
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| coppercone2:
does the liquid metal eutetic form a azeotrope when it boils or no? |
| Kleinstein:
I would not expect a eutectic system to also show an azeotrope. A eutectic system is usually found if the 2 metals don't like to mix well in the solid, but do mix in the liquid. An azeotrope is more found of the 2 components like each other very much in the liquid state so that the liquid is rather stable. So it may happen but is not likely. |
| IanB:
--- Quote from: DaJMasta on November 13, 2018, 03:38:14 am ---Yep, lead is 1750C and tin is 2600C, so if you get up there high enough, the lead will start boiling and keep things "cool" around 1750C until it's all gone. --- End quote --- That isn't quite how chemistry works. The boiling point of a mixture of substances is different from the boiling point of either pure substance. So for example the boiling point of an alloy of 60% tin, 40% lead is likely to be closer to the boiling point of tin than of lead. I cannot find quantitative data on the actual numbers since apparently the boiling of such alloys is not industrially or practically useful. However, since tin and lead adjacent to each other in the same group (14) of the periodic table they are likely to form a nearly ideal mixture. As such the boiling point of solder would be approximately half way between tin and lead. |
| coppercone2:
uh then how could you distill stuff? that's only true if it forms a azeotrope. |
| IanB:
--- Quote from: coppercone2 on November 17, 2018, 08:52:04 pm ---uh then how could you distill stuff? that's only true if it forms a azeotrope. --- End quote --- Actually no, it's true all the time. There is a common misconception that when you distill things, "the lightest substance distills over first", as if first the lightest thing boils off as a pure substance, and then the next thing boils, and so forth. This is a bit of an oversimplification and it is not exactly what happens. The reality is more complicated than this simple picture implies. What really happens is that the whole mixture boils, but the vapor coming off is richer in the lighter components than the liquid left behind. In a distillation apparatus the vapor is made travel up a column (maybe the long neck and glass tube attached to the flask in a laboratory apparatus). As the vapor travels up this column some of it condenses and falls back down while the rest of the vapor travels upwards as the temperature falls. By the time the vapor reaches the condenser it has ideally fallen to the boiling temperature of the substance you want to collect (a thermometer is used to check this). At that point what you condense should be your nearly pure product. But this only works if you carefully control the boiling rate and the condensing temperature. On the other hand, if you simply make a mixture of water and alcohol and boil it in an open vessel (danger, do not do this indoors), the vapor that comes off will be a mixture of water and alcohol too. You will not be able to achieve any meaningful separation by this means. |
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