MineMan
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Cant find phase diagrams:Al and Si
Hello. I have recently learned the melting point of Si and Al are greatly effected by pressure. I was able to find data on both elements for up to
50GPa. I cannot however find information on thier boiling points vs different pressures...
Silicon’s melting and boiling point is much higher than Al’s under STP. But under great pressure silicon’s MP decreases rapidly while aluminum's
increases.
Is it safe to assume the boiling point will follow the trend of the melting point... I don’t want to assume, I want numbers but I can find them?? I
am interested in this due to thier reactivitys with oxygen at high tempature. Obviously the lower the melting point the more reactive when one is
trying form oxides. But I know vapor or boiling tempature plays a role hence why magnesium is so reactive in fires.
Thank you all!
[Edited on 8-3-2019 by MineMan]
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DraconicAcid
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Quote: Originally posted by MineMan  |
Silicon’s melting and boiling point is much higher than Al’s under STP. But under great pressure silicon’s MP decreases rapidly while aluminum's
increases.
Is it safe to assume the boiling point will follow the trend of the melting point... I don’t want to assume, I want numbers but I can find them??
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The way the melting points are affected by pressure is due to the relative densities of the liquid and solid. Liquid silicon (like water), has a
higher density than the solid, so the melting point decreases with pressure. Liquid aluminum has a lower density than the solid, so its mp increases
with pressure.
Gases are always much, much less dense than the liquid, so their boiling points will always increase with pressure.
Please remember: "Filtrate" is not a verb.
Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
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MineMan
National Hazard
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Ok. Great answer. I see. That means under the combustion pressures of an explosive, magnesium, aluminum and etc don’ react in the vapor phase
because the pressure increases the boiling point!??
What about plasma however. It seems aluminum plasma is generated under pressure. Is the plasma a distinct phase, different density (disregarding the
tempature) then the vapor??
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