KINETICS of a CHEMICAL REACTION

1
KINETICS of a CHEMICAL REACTION

• S2O8-2 2I- ? I2 2SO4-2

2
S2O8-2 2I- ? I2 2SO4-2

• Rxn A S2O8-2 2I- ? I2 2SO4-2
• Overall rxn with k rate constant
• Rxn B 2S2O3-2 I2 ? 2I- S4O6-2
• Add S2O3-2 to react with iodine (product of Rxn
  A) fast rxn so 2I- constant until S2O3-2 is
  gone. Then I2 builds up.
• Rxn C I2 starch ? blue color

3
Purpose 1

• Study a chemical reaction as a function of
  reagent concentrations to determine its
• rate constant, k
• orders of reaction, n and m
• dS2O8-2/dt - k S2O8-2n I-m
• Eqn 3

4
Purpose 2

• Study the rate constant as a function of
  temperature
• k f(T) Eqn 7
• Arrhenius Eqn k(T) Aarrexp (-Ea/RT)
• Study the rate constant as a function of ionic
  strength.
• log k log k0 2A vI (ZA ZB) Eqn 17

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Purpose 3

• Apply a thermodynamic equilibrium model to this
  reaction to determine thermodynamic properties of
  the activated complex.
• Keq?
• ?H0?
• ?S0?
• ?G0?

6
Analysis of Data

• There are several parts to this experiment and
  the results from Day 1 are critical to your work
  on Day 2.
• See pages 45-47 in Lab Manual for details of data
  analysis.