Water electrostatic attraction

This topic has been dealt with in depth previously, and it should be particularly noted that in each type of hydrolysis the initial electrostatic attraction of the water molecule is followed by covalent bond formation and (in contrast to hydration) the water molecule is broken up. 

The internal structure of a liquid at a temperature near its freezing point has been discussed in Sec. 24. Each molecule vibrates in a little cage or cell, whose boundaries are provided by the adjacent molecules, as in Fig. 20, and likewise for each solute particle in solution in a solvent near its freezing point. It is clear that the question of the hydration of ions no longer arises in its original form. In aqueous solution an atomic ion will never be in contact with less than three or four water molecules, which in turn will be in contact with other water molecules, and so on. There is an electrostatic attraction, not only between the ion and the molecular dipoles in immediate contact with it, but also between the ion and molecular dipoles that are not in contact with it. For solvent dipoles that are in contact with a small doubly charged ion, such as Ca++,... 

It was stated before that the gas-phase lithium affinities of aziridine and oxirane were found to be 47 and 43 kcals/mole, respectively. These values might be somewhat overestimated since the Born formula used to compute the electrostatic attraction between Li and water may underestimate it. 

The present author has developed a novel method called ion-association method. This is also a simple and versatile method for the preparation of ion-based organic dye nanoparticles in pure aqueous solution by the ion association approach [23]. It utilizes the control of hydrophilicity/hydrophobicity of the ionic material itself via ion-pair formation for example, addition of a cationic target dye solution into aqueous solution containing a certain kind of hydrophobic anions forms an electrically neutral ion-pair because of the strong electrostatic attraction, followed by aggregation of ion-pair species originated from van der Waals attractive interactions between them to produce nuclei and the subsequent nanoparticles (Fig. 3). In this case, hydrophobic but water-soluble anions, such as tetraphenyl-borate (TPB) or its derivatives (tetrakis(4-fluorophenyl)borate (TFPB), tetrakis [3,5-... 

When placed in water, salts dissolve because the cations and anions are electrostatically attracted to the water molecules. The cations attract the oxygen ends of the water molecules, and the anions attract the hydrogen ends. When surrounded by water molecules, the ions are too for apart to exert a significant force of attraction on each other. Thus, the ionic bond is broken and the ions are said to be dissolved or hydrated. Once the surface ions have become hydrated, the underlying salt ions are exposed to water and eventually become hydrated as well. This process is illustrated in Figure 2.11. 

The addition of salt to water increases the viscosity of water. This is caused by the electrostatic attraction between the solutes and water. Because of slight spatial differences in salinity, the viscosity, and, hence, the speed of sound in seawater is also geographically variable. This is of practical consequence because the operation of SONAR (Sound Navigation Ranging) depends on a precise knowledge of the speed of sound in seawater. As described in Chapter 1, World War II made the need for accurate SONAR essential. This demand motivated the first detailed studies of the distribution of salinity and temperature in the ocean, which marked the beginning of the modern age of oceanography. 

The nonconservative behavior of seawater density and compressibility is caused partly by H bonding and partly by the electrostatic attractions exerted by the salt ions on their neighboring water molecules. The effect of these attractions can be estimated by trying to compute the density of seawater as a simple sum of the volumes of water and salt present in 1 kg of seawater (5 = 35%o and t = 4°C). As shown in Table 3.6, the actual density, as tabulated in the online appendix on the companion website (ct, = 27.81, so p = 1.02781 g/cm ), is about 1% higher than that predicted from summing the volumes of salt and water (1.0192 g/cm ). 

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