Water a polar solvent

Many, but not all, ionic compounds (e.g., NaCl but not CaC03) are soluble in water, a polar solvent In contrast, ionic compounds are insoluble in nonpolar solvents such as benzene (C6H6) or carbon tetrachloride (CCI4). 

Polar solute in water (a polar solvent). The hydration of sodium and chloride ions by water molecules overcomes the lattice energy of sodium chloride. The salt dissolves. 

In this example, ionization is favored by several factors. First, the benzyl ion formed is resonance-stabilized and bears a methoxy group in the para position that can further stabilize the cation by resonance. In addition, the leaving group is triflate, an exceptionally good leaving group. Finally, the ionization takes place in water, a polar solvent that can stabilize the two charged species formed. 

The difference in polarity and hydrogen bonding also explains the immis-cibility of alkanes and other hydrocarbons with water. If you try to dissolve alkanes, such as lubricating oils, in water, the two liquids separate almost immediately into two phases. This separation happens because the attractive forces between alkane molecules are stronger than the attractive forces between the alkane and water molecules. Therefore, alkanes are more soluble in solvents composed of nonpolar molecules like themselves than in water, a polar solvent. This is another example of the rule of thumb that like dissolves hke. ... 

There are two mechanisms by which microwaves interact with reaction mixtures [7]. Polarization of dielectric material arises when the distribution of an electron cloud is distorted or physical rotation of molecular dipoles occurs. For generation of heat on irradiation with microwaves, at least one component of a reaction mixture must have a dipole moment. Compounds with high dipole moments also have large dielectric constants, e. The selectivity of microwave irradiation is clear when comparing the heating of water and hexane. Water, a polar solvent, has a high dielectric constant and therefore heats rapidly on microwave irradiation whereas hexane, a nonpolar solvent, heats very slowly. 

Garbon tetrachloride is a nonpolar compound. In which solvent would you expect it to dissolve (a) Water (a polar solvent), (b) Gorn oil (a nonpolar solvent). 

Liquid-liquid extraction provides one of the most important commercial processes for performing group separations between aromatic and aliphatic species in the petrochemical industry. One of the earliest proven processes, the Udex system, is summarized in Fig. 7.8-9. It is based on the use of diethylene gly and water, a polar solvent, which selectively extracts the more polar aromatic conqxxmds fiom the nonpolar aliphatic species. A variety of solvents have been used including diethylene and Iriethylene glycols," N-methyl pyrrolidine, sulfolane, and other polar solvents. The basic process configurations ate similar to those already described, but in some cases a 1 solvent system may be used to remove asphaltic materials simultaneously. More recent studies give further consideration to alternative solvents for this application. 

Antigen-antibody reactions occur in aqueous solution. Therefore, after separating "free" and "bound" radioactivity in a radioimmunoassay, one must frequently measure the radioactivity of an aliquot of an aqueous solution. Here we are faced with the problem of dispersing water, a polar solvent, in a non-polar toluene or xylene based scintillator system. To minimize quenching problems, especially serious when counting weak beta particles such as those emitted by tritium, it is best if a homogenous mixture of the sample and liquid scintil-lant results. That is, two-phase systems should be avoided if possible. 

Write the net ionic equation for the reaction of a strong acid with a water-soluble hydroxide base in an aqueous solution. The solubility of HCl gas in water, a polar solvent, is much greater than its solubihly in hexane, a nonpolar solvent. How can you account for this difference ... 

Ethylene glycol is a polar molecule and dissolves readily in water, a polar solvent. 

An ionic solute dissolves in water—a polar solvent— because the polar water molecules attract and pull the ions into solution, where they become hydrated. 

In general, like dissolves like that is, polar substances tend to be soluble in polar solvents, and nonpolar substances tend to be soluble in nonpolar solvents. When an ionic compound dissolves in water, a polar solvent, the attractions between the water dipoles and the ions cause the ions to become solvated. The ions break away from the surface of the ionic soUd and move into solution. The overall energy change that occurs during solution formation is called the heat of solution. 

---