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Alka-Seltzer + Soap reaction rate

  1. Jan 12, 2012 #1

    I have seen that adding dish soap to water and then dissolving Alka-Seltzer in the solution causes the reaction rate to slow. Does anybody have any idea as to why this happens?
  2. jcsd
  3. Jan 14, 2012 #2


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    The surfactant must coat the tablet and this coating slows the reaction between the solid surface and the water. The tablet is a mix of bicarbonate and citric acid. These both must dissolve into the water before a reaction can occur. Perhaps the detergent has an affinity to one of reactants, likely citric acid, and forms a weak coating over it.
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