Journal of the American Chemical SocietyDOI: 10.1021/jacs.0c03990
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I do know the fact adding impurities to a particular will increase entropy, and thus lower the melting point of a solid. But why does it happen? Is there any concepts Im missing out?
Also, any good reading material on entropy topics? Thanks for the help!
the first lab I did in organic chem was a melting point lab. In it we combined solid cinnamic acid and solid uric acid, both crushed, and the melting point of the mix was less than either of the two compounds while they were pure. I can understand if the two were in liquid form, and how the intermolecular forces would be disrupted and the melting point would be lowered, though I don't get how two solids can be mixed and still get the same effect. can someone explain this to me?
So in Organic chem I the first lab we did was a melting point lab, where we explored melting point depression. We crushed urea (MP ~132C) and cinnamic acid (MP ~132C) and mixed the two powders, which then lowered the melting point of that mix to ~97C. I can understand both boiling point elevation and freezing point depression conceptually, but I'm just stumped thinking about two solids interacting so strongly. Can someone give me a general picture of what's going on at the crystalline/molecular level?
Why is tin Sn melting point so low compared to steel melting point? (Mostly iron and nickel)
The metallic bond in steel must be stronger but why? Tin has 4 valence elctrons so shouldn't it be hard to break the bonds?
a JW question asked which of the following has the highest melting point: LiF, LiCl, LiBr, and LiI and the answer was LiF. does this mean that the smaller the atomic radius, the higher the melting point? why is this the case and does this hold true for boiling point too?
I've seen videos of people putting fireproof safes (the cheap ones, not Fire King) into campfires and it showed that plastic melts, cds melt, but paper is fine if it's stored without plastic. I assume these campfires of course don't reach the intensity of a real housefire. Average housefire is 1,100 F/ 594 C.
Wikipedia says the M-disc has a melting point of somewhere between 392 and 1832 F/200 and 1000 C.
Since no one has no controlled tests the only safe solution would be having a 3 hour rated FireKing safe that costs $7,000 dollars or an offsite backup.
I have no one who I feel like will want to listen to me so I'm here to vent I guess and just get it out.
I have a small group of great friends who truly care for me and love me but my depression over the years has affected all my friendships and caused me to be unable to talk to them about how I am or go to them when I've hit a low.
I find it incredibly hard to talk to them out of fear that they don't care because I've always been like this or because I used to talk about it but it ended up pissing them off because all I did was doubt and worry. I have no one to go to now and I feel trapped in a bottle of my own anger and sadness, I fucking hate my depression and anxiety.
People will riot at this basic respect for thermodynamics.
It rained for the first time at the summit of Greenland's ice sheet
The rare rainfall was only the third time in less than a decade that above-freezing temperatures were recorded at the highest point on the ice sheet.
Aug. 19, 2021, 3:44 PM CDTBy Denise Chow
Rain fell for several hours at the highest point on the Greenland ice sheet last week — the first rainfall event in recorded history at a location that rarely creeps above freezing temperatures.
Scientists confirmed Wednesday that rain was observed Saturday at Summit Station, a research facility that sits atop the Greenland ice sheet and is operated year-round by the National Science Foundation. It was the first report of rain at the normally frigid summit, and it marks only the third time in less than a decade that above-freezing temperatures were recorded at the Arctic research station, according to the National Snow and Ice Data Center.
The rare rainfall caused significant melting at the summit and along the ice sheet's southeastern coast over the weekend and occurred just weeks after the region experienced a separate extensive melting event in late July. The recent warm spell adds to concerns that climate change is rapidly melting ice in the Arctic, which accelerates sea-level rise around the world.
It rained for the first time at the summit of Greenland's ice sheet (nbcnews.com)
For alkali metals, a larger period number means lower melting point. This makes kind of sense: as the nuclei get bigger and the atoms get more massive (but the number of valence electrons involved in the metallic bond stay the same), it is increasingly more difficult to hold the atoms together. Therefore the bond is weaker and easier to break.
For halogens the exact opposite happens. A larger period number corresponds to a higher melting point. My textbook says that the intermolecular bonds between diatomic molecules gets stronger and stronger as we go down the group. So for example the intermolecular bonds that form between Cl2 molecules are weaker than those that form between I2 molecules. Why is that? What kind of intermolecular forces arise between these molecules?
