cinetica de oxidacion del etanol

CINETICA DE OXIDACIÓN DE ETANOL POR Cr(VI)
1. INTRODUCCION
In studies of chemical kinetics is important to determine the rate expression that give the concentration of one or more of the reactantsor products as a function of time and obtain the rate constant k. It tries to follow its course through the exchange of some physical property such as pressure, absorbance, conductivity, refractiveindex, angle of rotation of polarized light, pH, etc.
The oxidation of alcohols with an oxidizing agent such as chromate is an example of homogeneous chemical reaction whose time monitoring functioncan be carried out easily. The progress of the reaction can be measured spectrophotometrically color change due to the reaction solution of the orange yellow (chemical species Corresponding HCrO4-) togreen (typical Cr3 + ion in solution).
  The reaction that occurs is:
3CH3CH2OH + 4HCrO4- + 16 H+ → 3CH3COOH + 4Cr3+ + 13H2O
The decrease in absorbance of the chromate is a direct measure ofthe variation of the amount of alcohol present in the mixture. To study the reaction to full speed law is of the form:
v= k[HCrO4-]x [CH3CH2OH]y[H+]z
However, underconditions where the concentrations of acid and ethanol are large and are kept approximately constant over the course of the reaction, the speed law is reduced to:
v=k'[HCrO4-]x

2. OBJETIVO
Calcular el orden y la constante de velocidad de una reacción mediante el uso de datos medidos experimentalmente y conocimientos de cinética química.

3. MATERIALES
-Espectrofotometro
- Bureta de 10 mL (para el agregado del H2SO4 4 M).
- Cronometro
- Balanza
- Matraces aforados de 50, 100 y 250 mL
- Pipetas aforadas de 1 y 2 mL
- Erlenmeyer de 125 mL.
-Tubos de ensayo

REACTIVOS
- H2SO4 4M
- K2Cr2O7 0,002 M en H2SO4 4 M.
- Etanol 0,4 M y 0,8 M (soluciones acuosas)

4. PROCEDIMIENTO

Encender el espectrofotómetro, seleccionar λ = 350 nm y...