Molecular substances nonelectrolyte

Each component of the mixture is assumed to be a molecular substance (nonelectrolyte), organic (i.e. containing carbon) or inorganic. Each substance has a well-defined relative molar mass corresponding to die natural isotopic abundances of the constitutive elements. Substances containing isotopically modified atoms are clearly identified in the tables which follow (Chap. 2). 

Let s start by calculating the molality of the solute. Ethylene glycol (HO-CH2CH2-OH, or EG for short) is an organic alcohol with a molecular mass of 62 g/mol. Since it is a molecular substance, it is a nonelectrolyte. 

Ionic compounds, strong acids, and strong bases (metal hydroxides) are strong electrolytes (completely broken up into ions of the compound). Weak acids and weak bases are weak electrolytes. Molecular substances other than acids or bases are nonelectrolytes. 

If our substance is a base, we use Table 4.2 to determine whether it is a strong base. NH3 is the only molecular base that we consider in this chapter, and Table 4.3 tells us it is a weak electrolyte. Finally, any molecular substance that we encounter in this chapter that is not an acid or NH3 is probably a nonelectrolyte. 

When a molecular compound such as sucrose or methanol [Figure 4.3(b)] dissolves in water, the solution usually consists of intact molecules dispersed throughout the solution. Consequently, most molecular compounds are nonelectrolytes. A few molecular substances do have aqueous solutions that contain ions. Acids are the most important of these solutions. For example, when HCl( ) dissolves in water to form hydrochloric acid, HCl(aq), the molecule ionizes that is, it dissociates into H (aq) and Cr(aq) ions. 

A nonelectrolyte is a substance that dissolves in water to give a nonconducting or very poorly conducting solution. A common example is sucrose, C12H22O11, which is ordinary table sugar. Another example is methanol, CH3OH, a compound used in car window washer solution. Both of these are molecular substances. The solution process occurs because molecules of the substance mix with molecules of water. Molecules are electrically neutral and cannot carry an electric current, so the solution is electrically nonconducting. 

Most soluble molecular substances are either nonelectrolytes or weak electrolytes. An exception is hydrogen chloride gas, HCl(g), which dissolves in water to produce hydrogen ions and chloride ions. We represent its reaction with water by an equation... 

Let ns snmmarize the main points in this section. Compounds that dissolve in water are soluble those that dissolve little, or not at all, are insoluble. Soluble substances are either electrolytes or nonelectrolytes. Nonelectrolytes form noncon-dncting aqneons solutions because they dissolve completely as molecules. Electrolytes form electrically conducting solutions in water because they dissolve to give ions in solntion. Electrolytes can be strong or weak. Almost all soluble ionic substances are strong electrolytes. Soluble molecular substances usually are nonelectrolytes or weak electrolytes the latter solution consists primarily of molecules, but has a small percentage of ions. Ammonia, NH3, is an example of a molecular substance that is a weak electrolyte. A few molecular substances (such as HCl) dissolve almost entirely as ions in the solution and are therefore strong electrolytes. The solubility rules can be used to predict the solubility of ionic compounds in water. 

Substances such as NaCl or KBr, which dissolve in water to produce conducting solutions of ions, are called electrolytes. Substances such as sucrose or ethyl alcohol, which do not produce ions in aqueous solution, are called nonelectrolytes. Most electrolytes are ionic compounds, but some are molecular. Hydrogen... 

Many reactions, particularly those that involve ionic compounds, take place in aqueous solution. Substances whose aqueous solutions contain ions and therefore conduct electricity are called electrolytes. Ionic compounds, such as NaCl, and molecular compounds that dissociate substantially into ions when dissolved in water are strong electrolytes. Substances that dissociate to only a small extent are weak electrolytes, and substances that do not produce ions in aqueous solution are nonelectrolytes. Acids dissociate in aqueous solutions to yield an anion and a hydronium ion, H30 +. Those acids that dissociate to a large extent are strong acids those acids that dissociate to a small extent are weak acids. 

A substance (such as NaCl) whose aqueous solutions contain ions is called an electrolyte. A substance (such as C12H22O11) that does not form ions in solution is called a nonelectrolyte. The different classifications of NaCl and C12H22O11 arise largely because NaCl is ionic, whereas C12H22O11 is molecular. 

Any substance whose aqueous solution contains ions is called an electrolyte. Any substance that forms a solution containing no ions is a nonelectrolyte. Electrolytes that are present in solution entirely as ions are strong electrolytes, whereas those that are present partly as ions and partly as molecules are weak electrolytes. Ionic compounds dissociate into ions when they dissolve, and they are strong electrolytes. The solubility of ionic substances is made possible by solvation, the interaction of ions with polar solvent molecules. Most molecular compounds are nonelectrolytes, although some are weak electrolytes, and a few are strong electrolytes. When representing the ionization of a weak electrolyte in solution, half-arrows in both directions are used, indicating that the forward and reverse reactions can achieve a chemical balance called a chemical equilibrium. 

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