Solutes weak acids

Determination of bismuth as oxyiodide Discussion. The cold bismuth solution, weakly acid with nitric acid, is treated with an excess of potassium iodide when Bil3 and some K[BiI4] are formed ... 

Strong acids (the acids listed in Table J.l) are completely deprotonated in solution weak acids (most other acids) are not. Strong bases (the metal oxides and hydroxides listed in Table J.l) are completely protonated in solution. Weak bases (ammonia and its organic derivatives, the amines) are only partially protonated in solution. 

Pale blue solution stable only in solution weak acid, Ka 4.5x10 . ... 

Classically, wall polysaccharides have been separated into three fractions the pectic polysaccharides, which are extracted by hot water, ammonium oxalate solution, weak acids, or chelating agents the hemi-celluloses, which can be extracted by relatively strong alkali and the residue remaining, which is composed mainly of cellulose. Although these extraction techniques suffer from incomplete and overlapping extraction of the polymers, they are still widely used. 

A substance that produces H+(aq) ions in aqueous solution. Strong acids ionize completely or almost completely in dilute aqueous solution. Weak acids ionize only slightly. 

The strengths of weak adds are measured on the pfCa scale. The p/<., value is the pH at which the acid and anion concentrations are equal (Table 2.1). The smaller the number on this scale is, the stronger the acid. In solution, weak acids do not fully dissociate into ions, but form equilibria between unchanged acid molecules and their respective charged anions and protons ... 

Table 4.2 lists a number of Brpnsted acids and their acid dissociation constants. Strong acids are characterized by values that are greater than that for hydronium ion (HsO, /fa = 55). Essentially every molecule of a strong acid transfers a proton to water in dilute aqueous solution. Weak acids have values less than that of H30 they are incompletely ionized in dilute aqueous solution. 

Class Ai. Compounds insoluble in water and in dilute sodium bicarbonate, but soluble in dilute sodium hydroxide solution. Weakly acidic compounds belong in this class. Weakly acidic properties are usually exhibited by oximes, imides, amino acids, sulfonamides of primary amines, primary and secondary nitro compounds, enols and phenols. Certain mercaptans also are weak acids. 

I Strong acids and strong bases are completely ionized in a dilute aqueous solution. Weak acids and weak bases are partially ionized in a dilute aqueous solution. 

White or colorless crystals becoming red on exposure to light characteristic odor melts at 41°C (105°F) boils at 182 C (359°F) moderately soluble in water [6.6% at 20° C (68°F)], dissolves in most organic solvents, insoluble in petroleum ether aqueous solution weakly acidic, pH 6.0. 

Strategy Recall that strong acids and strong bases are strong electrolytes. They are completely ionized in solution. An ionic equation will show strong acids and strong bases in terms of their free ions. Weak acids and weak bases are weak electrolytes. They only ionize to a small extent in solution. Weak acids and weak bases are shown as molecules in ionic and net ionic equations. A net ionic equation shows only the species that actually take part in the reaction. 

Strong acids and bases ionize completely in aqueous solutions. Weak acids and bases ionize only partially in aqueous solutions. An acid-base reaction is shown below. A titration was done by adding a base to a known concentration and fixed volume of an acid. The reaction follows ... 

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. 

Excellent chemical resistance to hydrocarbons, solvents, salt solutions, weak acids and bases 0.5% at 50% RH... 

Vg = equivalence volume 1. Initial solution—weak acid... 

Strong acids completely dissociate into ions in solution weak acids only partially dissociate. A concentrated acid is one which is not diluted with water, and the terms strong and concentrated should not be confused. 

HBr, strong acid (like HCl) KOH, a strong base KBr, neutral (neither ion is acid or base) KNH2, a strong base butyric is a weak acid like formic and acetic NOf is neutral, while the NH4 is a weak acid, making the solution weakly acidic acetate is a weak base Crlq is a weak acid. 

The acidity of a solution is normally specified by the concentration of H3O+ in moles per liter (M). Remember, however, that the concentration of H3O+ in an acid solution will not necessarily be equal to the concentration of the acid itself it depends on whether the acid is strong or weak. For example, a 1 M HCl solution (strong acid) will have an H3O+ concentration of 1 M, but a 1 M CH3COOH solution (weak acid) will have an H3O+ concentration significantly below 1 M. Consequently, we usually specify the acidity of a solution by referring to the H30 concentration directly rather than the concentration of the acid that formed it. We abbreviate the concentration of H3O+ by putting it in brackets ... 

The above equations show that a solution weak acid or base concentration close to the concentration of its salt will provide a constant pH equal to the pKa of the acid or base. 

---