Water motion 35 translational energy

A is correct. Heating the solid will raise its temperature which will eventually melt it. Compressing the solid will raise the pressure on the solid which will most likely keep it a solid. A few substances like water will melt under pressure, but for most solids, pressure changes a liquid to a solid. It is the random kinetic energy of the molecules of a solid and not the uniform translational motion kinetic energy of the solid that increases its temperature and would make it melt. 

Diffusion is defined as the random translational motion of molecules or ions that is driven by internal thermal energy - the so-called Brownian motion. The mean movement of a water molecule due to diffusion amounts to several tenth of micrometres during 100 ms. Magnetic resonance is capable of monitoring the diffusion processes of molecules and therefore reveals information about microscopic tissue compartments and structural anisotropy. Especially in stroke patients diffusion sensitive imaging has been reported to be a powerful tool for an improved characterization of ischemic tissue. 

Release of two water molecules from the cavity of a-cyclodextrin (form I) (19) is accompanied not only by the loss of van der Waals interaction (/fj jdw) and hydrogen bonding ( —2 A/fH.bond), but also by the gain of motional freedoms of two water molecules as to translation (2S ans) and three-dimensional rotation (2S ,I(3 D)). At the same time, a change in conformational energy of a-cyclodextrin is involved which is estimated by the use of Allinger s method (49). 

The RT motions of water are, therefore, effectively limited to molecular diffusion and those vibrations in the low energy part of the translational region. Hence the thermal displacement should be... 

Figure 14. Difference of averaged energies E(i) between total translational and total rotational motions plotted as a function of the system size. The difference was measured at l — 320 ps. Filled diamonds, squares, and crosses represent water, oxygen and alcohol molecules, respectively. The number of molecules is 216 and the temperature is 305 K.

Figure 15. The total potential energy fluctuation for the case (left) where rotational motions are suppressed, and the case (right) where the translational motions are suppressed. The simulation was performed for 64 water molecules with TIPS potential. The temperature is 298 K. [Reprinted with permission from Chem. Rev. 93, 2545-2566 (1993). Copyright 1993 by American Chemical Society.]...

Thus, it is expected that the preferential exclusion of ectoine should significantly alter the dynamic property of water molecules around the protein. In fact, our previous simulation showed that the diffusion constant of the water molecules in the first hydration layer of CI2 significantly slows down by the addition of ectoine [39]. This implies that, in the ectoine aqueous solution, the energy flow via the translational motion of solvent molecules should be weakened and be probably different in the characteristics in comparison with that in the pure water. For further studies, the surficial KB approach must be helpful in analyzing the energy flow mechanism in the mixed solvent environment. 

Molecular motions (rotation, translation, and vibration) of a water molecule also turn out to be quite different from those of other common liquids. Here all the six unique features of an individual water molecule outlined in Chapter 1 manifest themselves in diverse ways. As we discuss below, not only is the mechanism of displacements of individual water molecules different, but the collective dynamics and dynamical response of bulk water are also different. For example, the rotational motion of an individual water molecule contains a surprising jump component and vibrational energy relaxation of the O—H mode involves a cascading effect mediated by anharmonicity of the bond. These motions are reflected in many important processes such as electrical conductivity, solvation dynamics, and chemical reactions in aqueous medium. 

In the case of water, the situation is complicated because of the anisotropic nature of the potential. Thus, we have effective harmonic potential for translation, rotation, and librational motions. Each is characterized by a force constant and contributes to the partition function, free energy, and entropy. Furthermore, a water molecule can be categorized by the number of HBs it forms. Since these quantities can be considered as thermodynamic, they make a contribution as the entropy of mixing, also known as the cratic contribution. 

The internal energy of a system or body (for example, a unit of air volume) with well-defined boundaries, denoted by U, is the total kinetic energy due to the motion of particles (translational, rotational and vibrational) and the potential energy associated with the vibrational and electric energy of atoms within molecules or any matter state. This includes the energy in all chemical bonds and that of free electrons (for example, hydrated electrons in water and photons in air). 

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