7.9 Meaning of Rate of Reaction

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7.9 Meaning of Rate of Reaction

• Lesson outcome
• To be able to understand and apply to concept of
  rate of reaction

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Rate of Reaction

• Rate of Reaction
• - the rate at which reactants disappear or,
• - the rate at which products form

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EXAMPLE

• 2NO (g) O2 (g) ? 2NO2 (g)
• Nitric oxide is colourless whereas nitrogen
  dioxide is brown.
• We can follow the progress of this reaction by
  measuring the increasing intensity of the brown
  colour. This allows us to
• construct a graph of
• concentration of nitrogen
• dioxide as a function of time
• after mixing oxygen and
• nitric oxide this is shown
• in the Figure.

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So we can use concentration
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Back to the Example

• In this concentration vs time graph, the rate of
  reaction at any particular time is the slope of
  the curve

Rate ?c / ?t (c2 c1) / (t2 t1)
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