Rates of Chemical Reactions

1
Rates of Chemical Reactions

• Experiment 25

2
Reaction Rates

• Reaction Rates depend on several factors
• the nature on the reaction
• The concentration of the reactants
• The temperature
• Catalysts
• Reaction rates typically increase with an
  increase in concentration of reactants.

3
Equations

• A general reaction
• aA bB ? products
• The rate can be expressed as (rate law),
• Rate kAmBn
• m and n are usually small whole numbers (not
  related to stoichiometric coefficients), A and
  B are the concentrations of A and B, and k is a
  specific rate constant.

4
The Iodine Clock Reaction

• In todays experiment you will react potassium
  iodate and sodium hydrogen sulfite with each
  other to produce elemental iodine.
• You will use a starch solution to make the
  presence of iodine more noticeable.
• Iodine solution is a very pale yellow color, by
  adding the starch you will see a very sharp color
  change of blue/black.

5
Order of Reaction

• By measuring the time it takes for a reaction to
  occur at different concentrations of potassium
  iodate, you will be able to determine the order
  with respect to the iodate ion.

6
Procedure Notes

• Make sure you always use distilled water.
• Make sure all glassware is cleaned with soap and
  water then rinsed 3 times with distilled water.