Category Archives: Thermo

Electric Charge, Surfactants, Bubble Nucleation, and …

… Boiling of Water! Here’s a neat video about the work. Here’s a quote from an MIT News story on the research: “The whole concept relies on the fact that whether a surface is hydrophobic or hydrophilic will affect the … Continue reading

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Volume changes on melting

For most crystalline solids (in which the atoms/ions/molecules are packed tightly), we expect the density to fall on melting. This is somewhat easy to see for elemental metals. For example, the density of fcc Al falls from 2.7 g/cc to … Continue reading

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Freezing Water

You can start with beautiful, almost mesmerizing pictures of freezing of bubble walls in Angela Kelly’s photo set at Flickr. Here’s a pretty nice video of freezing of soap bubbles at an ambient temperature of -33 degrees Celsius. [You might … Continue reading

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Symmetric and Reversible

One of the popular ways of describing an irreversible process is to show a movie, and then run it in reverse. Evidently, it feels so wrong when it runs backwards, and therefore, … Entropy! A palindromic short film that is … Continue reading

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Thermodynamics of Chemical Reactions: Growing Si Nanowires

One of the cool things that an understanding of reaction equilibrium allows us to do is to manipulate the chemical potential of one of the species by controlling that of the other species that participate in a reaction. For example, … Continue reading

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Gas-Gas Miscibility Gaps?

Many binary phase diagrams display a miscibility gap in the solid state (Ni-Au) as well as in the liquid state (check out the monotectic transformations in the Cu-Se system). What about gas-gas miscibility gaps? Gases behave ideally at low pressures … Continue reading

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Boiling and Freezing in One Experiment

In this demo, acetone in a water-acetone solution is made to boil off by creating a low enough pressure. Acetone that leaves the system carries so much energy with it that the water-rich solution actually freezes! Watch this cleverly designed … Continue reading

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Mayer vs. Joule

Here’s something from the early history of thermodynamics: who should get the credit for the First Law? Just came across an interesting io9 article: Why Julius Robert von Mayer was one of the unluckiest men in science by Esther Inglis-Arkel. … Continue reading

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NPR Materials?

The previous post was on NLC materials that expand along some (but only some!) directions under an applied pressure. NLC, of course, stands for negative linear compressibility. The expansion along some directions is more than compensated by a shrinkage along … Continue reading

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How do materials respond to hydrostatic pressure?

Thermodynamic stability demands that the compressibility, , be positive. This means that the volume should decrease with increasing pressure. For fluids (gases and liquids), the volume decrease is accomplished by an equal decrease in linear dimensions along all directions. This … Continue reading

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