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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.
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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-.