CHAPTER 25 SOLUTIONS OF ELECTROLYTES

25-1 Solubility product constant

the ions in a saturated solution are in equilibrium with the

undissolved solid

the concentration of a solid such as AgBr is a constant because

the equilibrium between the solid and the liquid is

established at the surface of the solid. the number of ions

per square cm of solid surface is dependent on the crystal

structure which does not vary.

Ksp=[Ag+][Br-] (ex)

the solubility constant is derived from a special case of equilibrium

the addition of a common ion to a saturated solution causes a

precipitation of the solute

a solubility shift is predicted by LeChatelier's principle

the solubility product constant is the product of the molar

concentrations of ions in a saturated solution, raised

to the power of their coefficients from the balanced

chemical equation

25-2 ionization of water

pure water ionizes only slightly

in pure water [H₃O⁺]=[OH-]=1.00X10-⁷M

Kw is the ion product constant of water

if an acid is added to water the [H₃O+] increases and the [OH-]

decreases

if a base is added to water the [OH-] increases and the hydronium ion increases

25-3 pH scale

the pH scale is a simplified way of describing hydronium ion

concentration

neutral solution: pH=7

acidic solution: pH<7 max 0

basic solution: pH>7 max 14

pH + pOH=14

refer to pH Table 25-1 pg 498

Work Ph calculations on calculator with "log"

pH= -log[H₃O⁺]

25-4 Hydrolysis

a neutral solution results when the salt produced from a

strong acid and a weak base is dissolved in water

in hydrolysis the hydronium and hydroxide ions are produced

in solution and do not actually come from the dissolved

salt. they come from the ionized water molecules that

form as the salt dissolves and upsets the equilibrium

between the ions in water

hydrolysis is the reaction of a salt with water to produce an

acidic or basic solution

25-5 buffers

a buffer system can absorb moderate amounts of acid or base

without a significant change in pH

LeChatelier's principle can be used to predict the behavior

of a buffer solution

buffering of blood is upset when hyperventilation occurs

25-6 indicators

chemists use a pH meter to determine rapidly the degree of

acidity of a solution

indicators are used to determine pH through color change/they

are weak organic bases and acids whose colors differ from

their conjugate acids or bases

25-7 titration

titration is a quantitative process in which a standard solution

is used to determine the concentration of another solution

a buret used for titration is a carefully calibrated glass tube

designed to deliver measured volumes

indicators are used to determine the end point in a titration

acid + base = salt + water

1000cc=1 cdm= 1L