Chem101-9P

Chapter 9 Reaction kinetics Equilibrium laws Ion-product constant of water The pH concept Acid ionization constants Base ionization constants pKa and pKb concepts Chemical reaction buffers Acid-base titration

Kinetics Type of chemistry that “deals with the rates of chemical reactions.”

Rate of Chemical Reactions “Always expressed as a ratio.” Change in Concentration / Time mol/L ________ s

4 things that affect the rate 1.A catalyst is introduced to the reaction. 2.Nature of the reactants. 3.Temperature where the reaction is occurring. 4.The concentration of the reactants.

Collision theory Through kinetic movement particles of a reactant collide. If the collision is successful it causes electrons and nuclei to become reorganized relative to one another. This reorganization is what causes the product to have different properties then those of the reactants.

Chemical equilibrium When a chemical reaction reaches chemical equilibrium “the opposing reactions take place at identical rates.” aA + bB \===\ cC + dD

Equilibrium law Keq = [C]c [D]d / [A]a [B]b Keq is the equilibrium constant Equilibrium constant can be used to tell whether the products or the reactants are favored.

Equilibrium constant Keq < 1, reactants are favored at equilibrium Keq > 1, products are favored at equilibrium

equilibrium law for waster self- ionization Keq+ = [H+] [OH-] / [H2O]

ion product of water,” Kw= [H+] [OH-] Gained by multiplying both sides of water’s equilibrium law by H2O.

pH concept [H+] = 1 x 10-pH pH = - log [H+] A good way to quantify a solutions acidity Acidic solution has a pH < 7.00 Neutral solution has a pH = 7.00 Basic solution has a pH > 7.00

Acid ionization constant Ka = [H+] [A-] / [HA]

Base ionization constant Kb= [BH+] [OH-] / [B]

pKa and pKb The pKa is the negative logarithm of Ka and the pKb is the negative logarithm of Kb. pKa = - log Ka pKb = - log Kb

titration Procedure that is used to discern the neutralizing capacity of a solution. The procedure “compares the volume of a solution with an unknown concentration to the volume of a standard solution that exactly neutralizes it.” A standard solution being a solution that has a known concentration.

Chemical Buffer A buffer is a combination of solutes that is made up of a base and its conjugate acid. These two substances work together to neutralize other acids or bases.

Living Body’s Chemical Buffers Radical change in the pH balance in a living thing cause the life form perish. With out internal chemical barriers no living thing could exist.

Phosphate buffer Cell’s principal Chemical Buffer. Made up of a pair of ions, HPO42- and H2PO4-.

Carbonate buffer Buffer of the blood. Composed of the conjugate pair, H2CO3 and HCO3-.