Aqueous solutions weak electrolytes

Solutes that are water-soluble can be classified as either electrolytes or nonelectrolytes. Electrolytes are substances whose aqueous solutions conduct electric current. Strong electrolytes are substances that conduct electricity well in dilute aqueous solution. Weak electrolytes conduct electricity poorly in dilute aqueous solution. Aqueous solutions of nonelectrolytes do not conduct electricity. Electric current is carried through aqueous solution by the movement of ions. The strength of an electrolyte depends on the number of ions in solution and also on the charges on these ions (Figure 4-2). 

Electrolytes are substances whose aqueous solutions conduct electric current. Strong electrolytes are substances that conduct electricity well in dilute aqueous solution. Weak electrolytes conduct electricity poorly in dilute aqueous solution. Aqueous solutions of nonelectrolytes do not conduct electricity. 

Electrolytes strong electrolytes, such as NaCI, yield only ions when they dissolve in aqueous solution. Weak electrolytes, such as HF, exist as both ions and unionized molecules in aqueous solution. Nonelectrolytes, such as sucrose, 6 2 22 11 not form any ions in aqueous solution. 

Electrolytic dissociation in aqueous solution strong electrolytes weak electrolytes. Writing equations for electrode react >ns and over-all reactions. 

In Chapter 4, we classified solutes by their ability to conduct an electric current, which requires moving ions to be present. Recall that an electrolyte is a substance that dissociates into ions in aqueous solution strong electrolytes dissociate completely, and weak electrolytes dissociate very little. Nonelectrolytes do not dissociate into ions at all. To predict the magnitude of a colligative property, we refer to the solute formula to find the number of particles in solution. Each mole of nonelectrolyte yields 1 mol of particles in the solution. For example, 0.35 M glucose contains 0.35 mol of solute particles per liter. In principle, each mole of strong electrolyte dissociates into the number of moles of ions in the formula unit 0.4 M Na2S04 contains 0.8 mol of Na ions and 0.4 mol of S04 ions, or 1.2 mol of particles, per liter (see Sample Problem 4.1). 

We categorize acids arxJ bases as being either strong or weak electrolytes. Strong acids and bases are strong electrolytes, ionizing or dissociating completely in aqueous solution. Weak acids and bases are weak electrolytes and ionize only partially. 

Double layer structure in different media with a special attention paid to (1) concentrated aqueous solutions of electrolytes, (2) nonaqueous solvents, and (3) mixed solvents. Influence of the double layer field on the reactivity of adsorbed weak acids and bases. 

Decomposition or alteration of a chemical snbstance by water. (2) In aqueous solutions of electrolytes, the reactions of cations with water to produce a weak base or of anions to produce a weak acid. 

In a weak electrolyte (e.g. an aqueous solution of acetic acid) the solute molecules AB are incompletely dissociated into ions and according to the familiar chemical equation... 

Complete and Incomplete Ionic Dissociation. In the foregoing chapter mention has been made of electrolytes that are completely dissociated in solution, and of weak electrolytes where free ions are accompanied by a certain proportion of neutral molecules. In the nineteenth century it was thought that aqueous solutions of even the strongest electrolytes contained a small proportion of neutral molecules. Opinion as to the relation between strong and weak electrolytes has passed through certain vicissitudes and we shall describe later how this problem has been resolved. 

Consider the dissociation of a weak electrolyte, such as acetic acid, in dilute aqueous solution ... 

The solute in an aqueous strong electrolyte solution is present as ions that can conduct electricity through the solvent. The solutes in nonelectrolyte solutions are present as molecules. Only a small fraction of the solute molecules in weak electrolyte solutions are present as ions. 

Determine the freezing point of a 0.10 mol-kg aqueous solution of a weak electrolyte that is 7.5% dissociated into two ions. 

In aqueous electrolyte solutions the molar conductivities of the electrolyte. A, and of individual ions, Xj, always increase with decreasing solute concentration [cf. Eq. (7.11) for solutions of weak electrolytes, and Eq. (7.14) for solutions of strong electrolytes]. In nonaqueous solutions even this rule fails, and in some cases maxima and minima appear in the plots of A vs. c (Eig. 8.1). This tendency becomes stronger in solvents with low permittivity. This anomalons behavior of the nonaqueous solutions can be explained in terms of the various equilibria for ionic association (ion pairs or triplets) and complex formation. It is for the same reason that concentration changes often cause a drastic change in transport numbers of individual ions, which in some cases even assume values less than zero or more than unity. 

All biological systems contain aqueous electrolyte solutions. These solutions consist of strong electrolytes (inorganic salts) as well as various organic substances with acidic or basic functional groups which usually behave as weak electrolytes. The solutions are often gel-like in their consistency because of the polyelectrolytes, proteins, and other macromolecules contained in them. The pH values of biological solutions as a rule are between 6.7 and 7.6. 

A molecule HA of a weak electrolyte is now considered. It is assumed to dissociate in its aqueous solution according to the equation HA =f H+ + AT The application of the law of mass action to the above equation gives... 

Arrhenius postulated in 1887 that an appreciable fraction of electrolyte in water dissociates to free ions, which are responsible for the electrical conductance of its aqueous solution. Later Kohlrausch plotted the equivalent conductivities of an electrolyte at a constant temperature against the square root of its concentration he found a slow linear increase of A with increasing dilution for so-called strong electrolytes (salts), but a tangential increase for weak electrolytes (weak acids and bases). Hence the equivalent conductivity of an electrolyte reaches a limiting value at infinite dilution, defined as... 

The species appearing as strong electrolytes in aqueous solutions lose this property in low-permittivity solvents. The ion-pair formation converts them to a sort of weak electrolyte. In solvents of very low-permittivity (dioxan, benzene) even ion triplets and quadruplets are formed. 

Electrolytes are defined as substances whose aqueous solutions conduct electricity due to the presence of ions in solution. Acids, soluble bases and soluble salts are electrolytes. Measuring the extent to which a substance s aqueous solution conducts electricity is how chemists determine whether it is a strong or weak electrolyte. If the solution conducts electricity well, the solute is a strong electrolyte, like the strong acid, HC1 if it conducts electricity poorly, the solute is a weak electrolyte, like the weak acid, HF. 

To distinguish between strong electrolytes, weak electrolytes and nonelectrolytes, prepare equimolar aqueous solutions of the compounds and test their electrical conductivity. If a compound s solution conducts electricity well, it is a strong electrolyte if its solution conducts electricity poorly, it is a weak electrolyte. A solution of a nonelectrolyte does not conduct electricity at all. 

Dilute aqueous solutions of weak acids, such as HF and HN02, contain relatively few ions because they are weak electrolytes, ionize only slightly into their ions and are therefore, poor conductors of electricity. This can be demonstrated using a conductivity apparatus as shown in Figure 6-1. 

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